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Influence of aridity on reproduction of the collared peccary (Dicotyles tajacu (linn)) in Texas Low, William A 1970

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THE INFLUENCE OF ARIDITY ON REPRODUCTION OF THE COLLARED PECCARY (PICOTYLES TAJACU (LINN)) IN TEXAS by WILLIAM A. LOW B.Sc. (Honours), University of B r i t i s h Columbia, 1962 A THESIS SUBMITTED IN THE REQUIREMENTS DOCTOR OF PARTIAL FULFILMENT OF FOR THE DEGREE OF PHILOSOPHY i n the Department of Zoology We accept t h i s t hesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA 1970 In presenting th is thes is in pa r t i a l fu l f i lment o f the requirements for an advanced degree at the Univers i ty of B r i t i s h Columbia, I agree that the L ibrary sha l l make i t f r ee l y ava i lab le for reference and study. I fur ther agree that permission for extensive copying of th i s thes is for scho la r l y purposes may be granted by the Head of my Department or by his representat ives . It is understood that copying or pub l i ca t ion of th is thes is fo r f inanc ia l gain sha l l not be allowed without my wri t ten permission. Department of Zoology  The Univers i ty of B r i t i s h Columbia Vancouver 8, Canada Date October 26. 1970 i i ABSTRACT ' R e p r o d u c t i o n and p r o d u c t i v i t y o f t h e c o l l a r e d p e c c a r y , D i c o t y l e s  t a j a c u a n g u l a t u s , were examined i n Texas under m o i s t and d r a u g h t c o n d i t i o n s , and i n c a p t i v i t y under presumed o p t i m a l c o n d i t i o n s . F o e t a l s e x r a t i o s f a v o u r f e m a l e s , l a u t change t o f a v o u r males s h o r t -I y a f t e r b i r t h , and a g a i n f a v o u r f e m a l e s i n t h e o l d e r age c l a s s e s . The s o u t h Texas p o p u l a t i o n c o n t a i n e d a h i g h e r p r o p o r t i o n o f o l d e r a n i m a l s t h a n t h e west Texas p o p u l a t i o n . L i f e e x p e c t a n c y a t 1 y e a r o f age was e s t i m a t e d a t 3.0 y e a r s i n s o u t h Texas p e c c a r i e s , a n d t h e a v e r a g e a n n u a l m o r t a l i t y r a t e was 21.5°/o. z The m o r t a l i t y r a t e f o r west Texas p e c c a r i e s was c a l c u l a t e d a t 27.5°/>. i A n i m a l c o n d i t i o n , e s t i m a t e d f r o m k i d n e y f a t and c a r c a s s weight,was h i g h e s t i n t h e l a t e f a l l , a n d was s i g n i f i c a n t l y b e t t e r i n t h e y e a r o f h i g h i r a i n f a l l and good range c o n d i t i o n s t h a n d u r i n g t h e drought y e a r . C o n d i t i o n o f t h e s o u t h Texas p e c c a r i e s under good range c o n d i t i o n s was a l m o s t as h i g h as t h a t o f p e n - r e a r e d a n i m a l s , and under drought c o n d i t i o n s a l i s o s t as low as t h e west Texas p e c c a r i e s under gao'd c o n d i t i o n s . M ales mature s e x u a l l y pt^, j u s t under a y e a r . A l t h o u g h t h e r e a r e s e a s o n a l changes i n t h e p r o p o r t i o n o f t e s t i s c o n s t i t u e n t s , abundant sperm a r e p r e s e n t i n a t l e a s t some males a t a l l t i m e s o f t h e y e a r . Females appear s e x u a l l y mature a t j u s t ' under a yearj, but i n t h e w i l d p o p u l a t i o n s do not become p r e g n a n t u n t i l 16 t o 20 months'. P e n - r a i s e d a n i m a l s h^ve a f e r t i l e p o s t -par^um and l a c t a t i o n oestruses,; and g e n e r a l l y , nroduce two l i f t e r s a y e a r . I n s o u t h ' T e x a s 33°//ofj th e a d u l t sows showed o v a r i a n e v i d e n c e o f c o n s e c u t i v e p r e g n a n c i e s . ' D u r i n g f a v o u r a b l e r a n g e ' c o n d i t i o n s 71°/o o f t h e c o l l e c t e d sows we're pre.gnant and 41°/o had' remated. D u r i n g d r o u g h t c o n d i t i o n s o n l y 2670 o f t h e sows were p r e g n a n t and 9% remated. A good i t measure o f c o n s e c u t i v e p r e g n a n c i e s i n , west Texas was not o b t a i n e d , but i t i i a o p e a r s comparable t o s o u t h Texas under drought c o n d i t i o n s . There was no \ ; ; I aDparent d e c r e a s e i n r e p r o d u c t i o n i n 15-year o l d s o u t h Texas and 9-year o l d west T e x a s female's Thjere was a m a j o r b r e e d i n g p e r i o d i n m i d - w i n t e r andj a m i n o r one i n l a t e , s p r i n g i n s o u t h Texas. f-; E v i d e n c e i s l i m i t e d f o r west Texas, but most c o n c e p t i o n s o c c u r i n l a t e w i n t e r . Good range c o n d i t i o n s a r i s i n g from f a v o u r a b l e r a i n f a l l , Dattjernsj r e s u l t i n e a r l y A w i n t e r b r e e d i n g and s t r o n g ^ s p r i n g br^ee.ding a c t i v i t y i n south' Texas. Drought c o n d i t i o n s r e t a r d the w i n t e r b r e e d i n g season'and almos^t e l i m i n a t e l a i s e s p r i n g . b r e e d i n g . 1 i i i . G r o s s p r o d u c t i v i t y o f penned a n i m a l s was 425 young/1OD a d u l t sows. South Texas sows a v e r a g e d 240 young/100 a d u l t sows d u r i n g t h e s t u d y . No measure i s a v a i l a b l e f o r west Texas sows. D u r i n g good range c o n d i t i o n s g r o s s p r o d u c t i v i t y was 288 young/100 a d u l t sows, and d u r i n g t h e d r o ught 151 young/100 a d u l t , sows. Net p r o d u c t i v i t y i n s o u t h Texas d u r i n g t h e s t u d y was 81 u n d e r -1-year o l d s / 1 0 0 a d u l t sows and 53 ( y e a r l i n g s ) / l 0 0 a d u l t sows. I n west Texas t h e r e were 45 ( y e a r l i n g s ) / l 0 0 a d u l t sows. P r e d s t i o n and p a r a s i t i s m a r e p r o b a b l y o f minor i m p o r t a n c e t o t h e p o p u l a t i o n s . Combined c o l d w e ather and d r o u g h t r e s u l t e d i n a d e c r e a s e o f 29°/o o f two h e r d s , and c o u l d f u n c t i o n as a f a c t o r c o n t r o l l i n g p o p u l a t i o n s . D raught, t h r o u g h i t s e f f e c t on f o o d a v a i l a b i l i t y , a p p e a rs t o be t h e p r i m a r y c o n t r o l l i n g f a c t o r o f p e c c a r y p o p u l a t i o n s i n Texas. iv. TABLE OF CONTENTS ABSRACT . i i LIST OF FIGURES v i LIST OF TABLES v i i i LIST OF PLATES xi ACKNOWLEDGEMENTS x i i i 1 . INTRODUCTION 1 2. STUDY AREAS 4 2.1. Physiography 4 2.2. Climate 6 2.3. Vegetation 14 2.4. Competitors and predators 18 3. MATERIALS AND METHODS 20 3.1. Collected animals 20 3.2. Live trapping 21 3.3. Field observations 22 3.4. Pen-reared animals 23 3.5. Age determination 23 3.6. Sex determination 24 3.7. Census 24 3.8. Food habits 25 3.9. Growth 25 3.10. Condition 26 3.11. Male reproduction 26 3.12. Female reproduction 27 3.13. S t a t i s t i c a l treatment 29 4. RESULTS 30 4.1. Food habits 30 4.2. C o n d i t i o n 30 4.3. Growth 35 4.4. The population 45 4.4.1. Density 45 4.4.2. Home range and movements 46 4.4.3. Population structure 47 Sex ratio 47 Age structure 48 4.5. Male reproduction 52 4.5.1. Morphology of the male reproductive tract 52 4.5.2. Growth and seasonal change in testis size 52 4.5.3. Histological examination of testes 60 4.5.4. Seasonal changes in histological structure of testes 63 4.6. Female reproduction 55 4.6.1. The reproductive tract and mammae 65 4.6.2. The ovary 65 4.6.3. The reproductive cycle 77 Oestrous period and cycle 77 Gestation period 79 Frequency of gestation 79 4.6.4. Maturation 81 V. 4.6.5. S e n i l i t y 83 4.6.6. Breeding Season 84 4.6.7. L i t t e r Size 90 4.7. Productivity 90 4.7.1. Ovulation incidence 90 4.7.2. Implantation incidence 93 4.7.3. Ovulation and implantation rates 95 4.7.4. Productivity of age classes 95 4.7.5. Gross and net productivity 97 5. DISCUSSION 100 6. APPENDIX 120 A. L i s t of s c i e n t i f i c names 121 B. Handling trapped and captive peccaries 123 C. Age determination of peccaries 125 1. Young and adult peccaries 125 2. Foetal peccaries 143 D. Age-specific body measurements and weights of south and west 148 Texas male and female peccaries E. Spermatogenic a c t i v i t y of a selected series of testes from the '-. 150 collared peccary F. Age—specific size of ovaries and ovarian structures 152 G. Mortality factors affecting peccary populations 155 J 7. LITERATURE CITED 161 8. BIOGRAPHICAL INFORMATION . 1 7 0 v i . LIST OF FIGURES 1. Location of the study areas, and r a i n f a l l and evaporation 5 d i s t r i b u t i o n i n Texas. 2. Monthly average, maximum, and minimum temperatures 8 for four areas. a. K i n g s v i l l e b. Welder Refuge c. Watson Ranch d. Black Gap 3. Deviation of monthly r a i n f a l l from the long-term monthly aver- 9 ages on the King Ranch and Welder Refuge. 4. Deviation of monthly r a i n f a l l from the long-term monthly aver- 10 age near the Watson Ranch and Black Gap areas. 5. A r i d i t y index for the Welder Refuge. 12 6. Forage class composition of the stomach contents of 73 collared 32 peccaries from south Texas. 7. Seasonal changes i n kidney f a t index i n south Texas 34 peccaries during moist and drought conditions, 1965-1967. 8. Relationship of l i v e weights to age of pen-reared and collected 38 south Texas peccaries. 9. Comparison of carcass weights of south and west Texas male > 40 peccaries by year class. 10. Comparison of carcass weights of south and west Texas female 40 peccaries by year class. 11. Live and carcass weights of trapped and collected female pec- 43 caries older than two years. 12. Live and carcass weights of trapped and collected male pec- 44 caries older than two years. 13. Age d i s t r i b u t i o n of peccaries collected i n south and west Texas. 49 14. Change i n t e s t i s index (T.I.) with age of south and west Texas males. 56 15. Seasonal change i n t e s t i s index of adult south Texas males. 56 16. Change i n t e s t i s index, sperm counts, proportion of tubules, 62 and tubule diameter with age of south Texas males. 17. Seasonal changes i n t e s t i s size and h i s t o l o g i c a l structures 64 of 18 adult south Texas males. 18. Seasonal changes i n size of ovarian medulla for a l l sows two years and older collected i n south Texas. 19. Change i n volume of the corpus luteum of pregnancy with progress of gestation period. 20. Regression of the corpus luteum of pregnancy after p a r t u r i t i o n . 21. Seasonal changes i n breeding a c t i v i t y of adult female peccaries i n south Texas. 22. Month of b i r t h of young i n south Texas. 23. Month of b i r t h of young i n west Texas. 24. Factors affecting peccary populations. 25. Model of process of population change i n south Texas peccary populations. Appendix C. Fig. 1 Lens weight d i s t r i b u t i o n by a) age class and b) annulation age of south Texas peccaries. Fi g . 2 Regression of lens weight on age of known-age peccaries<21 months old and of a l l south Texas peccaries < 24 months old. Fig. 3 Tooth eruption progression f o r south Texas peccaries. Fi g . 4 Comparison of age determined by dental annulations and wear class f o r south and west Texas peccaries. Fig. 5 Crown-rump growth curves of foetal domestic pig and black-t a i l e d deer plotted i n the same i n t e r v a l and used "'for predicting the age of f o e t a l peccaries. v i i i . LIST OF TABLES Table. 1. 2. Climate-logical characteristics of the four study areas. Comparison of F a l l kidney f a t indices of adult captive, south Texas, and west Texas peccaries under different moisture condi-tions . 7 .35 35 3. Weights of pen—raised and wild neonatal peccaries. 36 4. Size comparison of adult peccaries from south and west Texas. 41 5. Comaprison of carcass weights of adult south and west Texas peccaries between low- and h i g h - r a i n f a l l periods. 42 6. Peccary density estimates i n Mesquite Pasture of the King pianch, from s t r i p census. -45 7. Peccary density estimates on the four study areas i n south and west Texas. 46 8. Age-specific sex r a t i o s of pen-born, south Texas, and west Texas peccaries. 47 9. Age-specific sex r a t i o s of young south Texas peccaries conceived or born i n different climatic conditions. 48 10. L i f e Table f o r south Texas peccaries based on 218 peccaries. 51 11 . L i f e Table f o r west Texas peccaries older than 12 months, based on 102 peccaries. 51 12. Growth of testes of south Texas peccaries. 52 13. Age—specific t e s t i s indices f o r adult south Texas males. 57 14. Growth of testes of west Texas peccaries. 57 15. Age s p e c i f i c t e s t i s indices f o r adult west .Texas males. 58 16. Testis indices of pen-^reared peccaries. 59 17. Testis indices of adult south Texas peccaries compared by r a i n -f a l l l e v e l s . 59 18. Testis indices of adult west Texas peccaries compared by month and year. 60 19. Interval between p a r t u r i t i o n and f e r t i l e oestrus i n pen-reared peccaries. 80 Table. 20. Incidence of consecutive pregnancies i n south and west Texas peccaries. 21. Behavioral maturation of female pen-reared peccaries. 22. L i t t e r s i z e i n peccaries. 23. Age-specific pregnancy, ovulation, and implantation incidences of captive, south Texas, and west Texas peccaries. 24. Seasonal ovulation and implantation incidences, and reproductive index of adult south Texas peccaries. 25. Proportion of adult sows showing evidence of consecutive preg-nancies i n south and west Texas during drought and high r a i n f a l l periods. 26. Productivity of adult south Texas peccaries. 27. Proportion of young observed i n population at monthly and quarterly i n t e r v a l s . 28. Peccary density estimates on the King Ranch Appendix B. Table 1. Tranquilizing and immobilizing drugs, and successful dosages used on penned and trapped peccaries. Appendix C. Table 1. Comparison of known—age and annulation—age of peccaries pen-reared by L.K. Sowls i n Arizona and during t h i s study at U.B.C. and the Welder Refuge. Table 2. Estimate of ages and conception dates of f o e t a l peccaries from crown-rump length and weight. Appendix D. Table 1, Age-specific weight and body measurements of peccaries collected i n south Texas. Table 2. Age-specific weight and body measurements of peccaries collected i n west Texas. Appendix E. Table 1. Spermatogenic a c t i v i t y of a selected series of testes from the collared peccary. X . Appendix F. Table 1. Age—specific weights and volumes of ovaries and ovarian 153 structures of pregnant and non-pregnant south Texas peccaries. Table 2. Age—specific weights and volumes of voaries and ovarian 154 structures of pregnant and non-pregnant west Texas peccaries. Appendix G. Table 1. Stomach contents of canid and f e l i d predators trapped on the 155 Santa Gertrudis division,'King Ranch. Table 2. Cause of death of peccaries found dead i n south Texas. 156 Table 3. Prevalence and abundance of parasites of the collared peccary i n Texas. 158 LIST OF PLATES Frontispiece Collared peccary feeding i n a p r i c k l y pear-halophyte community. 1. Representative peccary habitat i n south and west Texas a. One-year old root-plowed chaparral-prickly pear community on the King Ranch i n south Texas. b. Several-year old root-plowed chaparral-prickly pear community on the King Ranch. c. A densely vegetated community of the lowland desert scrub a s s o c i a t i o r r . i n west Texas. 2. The male reproductive tr a c t a. The entire t r a c t . b. Cross-section of the t e s t i s one-third of the distance from the caput epididymis. c. Cross-section of the t e s t i s i n the central region. d. Cross-section of the t e s t i s one-third of the distance from the cauda epididymis. 3. The female reproductive tr a c t a. Reproductive tr a c t of a pregnant sow. b. Ovary from non-pregnant sow. c. Ovary with two corpora lutea. d. Ovary with one corpus luteum. 4. Ovaries and ovarian structures a. Ovary of an 82-day post-conception foetus. b. Ovary of neonatal peccary. c. Lipocytic c e l l s adjacent to ovarian medulla i n adult female ovary. d. Tubule i n ovarian medulla of 9—year old west Texas sow. e. I n t e r s t i t i a l c e l l s of ovarian medulla of non—pregnant sow. f. I n t e r s t i t i a l c e l l s of t e s t i s of adult male. g. The rete o v a r i i i n a 9—year old west Texas sow. h. The rete o v a r i i i n a f o e t a l ovary. 5. Ovarian structures a. Primordial f o l l i c l e s i n band around periphery of cortex. b. Ovarian medulla of pregnant sow. c. Ovarian medulla of non-pregnant sow. d. C o r t i c a l structures of an adult ovary. e. Degenerating CL-NP. f. Degenerating CL-P. g. Involuted appearance of rapidly growing CL-P. x i i . h. G r a n u l o s a l u t e a l c e l l s i n n o n - v i a b l e c o r p u s l u t e u m . i . S c a r o f p a s t pregnancy ( c o r p u s a l b i c a n s ) . A p pendix C. P l a t e 1. A n n u l a t i o n s i n t o o t h cementum. 140 a. The method o f c o u n t i n g a n n u l a t i o n s i n t h e cementum o f t h e f i r s t i n c i s o r . b. S t r o n g a n n u l a t i o n s i n t h e cementum o f an 8-year o l d f e m a l e ( P - 1 2 ) . c. Weak a n n u l a t i o n s i n t h e cementum o f a 6-year o l d f e m a l e ( P - 1 4 ) . d. F a i n t and s t r o n g a n n u l a t i o n s i n t h e cementum o f a 10-year o l d f e m a l e ( P - 8 1 ) . x i i i . ACKNOWLEDGEMENTS Many people gave kindly of t h e i r time, assistance and advice dur-ing t h i s project. I t i s impossible to mention a l l of them here and to those not s p e c i f i c a l l y mentioned I am grateful for t h e i r help. I am p a r t i c u l a r l y indebted to Dr. Ian McTaggart Cowan f o r sug-gesting and f o r constructive c r i t i c i s m of the study, providing funds for equipment and expenses, giving encouragement during times of f r u s t r a t i o n and for bearing with me during the long gestation and d i f f i c u l t b i r t h of t h i s thesis. Dr. Clarence Cottam, Director, and Mr. W.C. Glazener, Assistant Director, of the Welder W i l d l i f e Refuge provided many helpful suggestions and c r i t i c i s m s from the conception of the study. I am grateful to them and to the trustees of the Welder W i l d l i f e Foundation f o r providing l i v i n g quarters, equipment a .d extra help when i t was needed. The Welder Refuge s t a f f , students, v i s i t o r s , summer assistants and t h e i r families were extremely helpful. Olney Maley, Ruby Lou Hranicky, Celso V i l l a r e a l , Anne Speers, Willna Glazener, Je f f Kirby and Jack I n g l i s helped i n various ways. Students Dean Chamrad, Marshall White, E r i c Bolen, Bob Cook, Jef f Powell, Duane G a l l , Lynne Drawe, and Ron Hood, long-term v i s i t o r s Thadis Box, Walter Robertson, John T. Emlen, J r . and Richard Heape, summer assistants Ken Matocha, Bruce F a l l , Mike Fleming, the C a s t i l l o brothers, Alonzo and Gilberto, and John Beecham a l l provided i n -formation, advice or assistance. B i l l Samuel and Rick White, respectively, undertook j o i n t studies of parasites and food habits, which added important information to the study. I p a r t i c u l a r l y enjoyed and appreciate the many hours that Bob Watts put i n helping with f i e l d work and autopsies and d i s -cussing various aspects of the study. His enthusiasm was stimulating. Numerous residents of the Sinton area made my stay i n Texas enjoyable. Debbo and Momma I I Featherling w i l l always be remembered. Mr. Valgene W. Lehmann, W i l d l i f e B i o l o g i s t f o r the King Ranch, aided i n the conception of the study. I appreciate the aid which he provided i n obtaining approval of the King Ranch, Inc. f o r much of the study to be conducted on the Ranch. I wish to thank the King Ranch, Inc. and Mr. Robert J. Kleberg, J r . , president, f o r providing permission, traps, bait, personnel and climatic data used during the study. Mr. William H. x i v . K i e l , J r . , and the W i l d l i f e crew f a c i l i t a t e d various aspects of the f i e l d study on the King Ranch. I am p a r t i c u l a r l y grateful to George Schacherl, then predatory animal trapper on the King Ranch, for the many hours of companionship and help i n the f i e l d . Few men are more dedicated and conscientious than he. The s t a f f and students at Texas A & I University, p a r t i c u l a r l y the W i l d l i f e Biology class, provided useful discussion and c r i t i c i s m . Mrs. Ralph Watson, and her daughter Mrs. Cardin, very kindly granted permission to me to c o l l e c t peccaries on the ranch south of Ozona. I greatly appreciated the accommodation provided while Bobbi and I stayed there. Members of the Texas Parks and W i l d l i f e Dept. provided c o l l e c t i n g permits and helpful suggestions. Pierce Uzzel i n Austin, and the Black Gap crew, Sam Brownlee, Durward (El Diablo) Avery, Tommy Hailey, and the C.O.s and b i o l o g i s t s assigned to the public hunt were p a r t i c u l a r l y h e l p f u l . Dr. L. K. Sowls kindly provided teeth from known—age peccaries raised during his study of peccaries i n Arizona. He also provided useful discussion at the outset of the study. Many students and faculty at the University of B.C. provided helpful suggestions. Drs. D. Chitty, V. J. Krajina, A. J. Wood, J. Adams and J. F. Bendell served as my thesis committee and I appreciated t h e i r constructive c r i t i c i s m . Dr. J. M. Taylor provided useful suggestions dur-ing the termination of the study and Dr. P. J . Larkin provided helpful s t a t i s t i c a l information, p a r t i c u l a r l y on mortality rates. Many of the Zoology s t a f f have been very helpful; I p a r t i c u l a r l y appreciate the conscientious e f f o r t s of Armand Tepper In. looking a f t e r the peccaries raised at U.B.C., and of Gladys Welsby i n keeping the administrative part of the study going smoothly while I was i n Texas and at U.B.C. Don Thomas was p a r t i c u l a r l y helpful with the ovarian analysis, and I have enjoyed many hours of discussion with him. Don Eastman and Lynne Kemper helped with various aspects of the study. I am grateful to Dr. P. J . Bandy for his many forms of help on t h i s and past projects, and to "the B.C. Fish and W i l d l i f e Branch for support during my early graduate research. Members of the Rangelands Research Unit, CSIRO, p a r t i c u l a r l y Mr. Ray Perry, were helpful during the f i n a l write up. XV. I thank A l i c e Thomas for her many re-typings of the drafts of the thesis, and Boyne Carragher for typing the f i n a l draft. During the study I was supported by N.R.C. and U.B.C. Fellow-ships . Last, and probably most, I thank my wife, Bobbi, f o r her con-tinuing support and encouragement, for many discussions of various aspects of the study, f o r her unselfish aid i n a l l aspects of f i e l d and laboratory work, f o r constructively c r i t i c i s i n g the various drafts, and for drawing the figures i n the thesis. I t i s not possible to express adequately my appreciation to her for her efforts on my behalf. x v i . In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t fr e e l y available f o r reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. I t i s understood that copying or publication of t h i s thesis f o r f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of Zoology The University of B r i t i s h Columbia Vancouver 8, Canada 1. THE INFLUENCE OF ARIDITY ON REPRODUCTION OF THE COLLARED PECCARY (PICOTYLES TAJACU (LINN.)) IN TEXAS 1. INTRODUCTION Climatic forces, as the immediate cause of short term, large scale losses to domestic and wild ungulates, are well known. It has also been shown that certain species, such as caribou (Rangifer) liv i n g in regions where climatic hazards occur frequently, can experience imbalance of reproductive input against mortality through a span of years that renders management for a crop tenuous (Kelsall, 1969). Andrewartha and Birch (1954) have suggested that such environmental forces acting in a non-density dependent manner may sometimes act as effective regulators of animal numbers. The collared peccary (Dicotyles tajacu (Linn.)) in the United States i s at the northern extremity of i t s range. Here i t occupies an arid environment in which r a i n f a l l i s irregular, and lengthy and frequent periods of drought occur. The species has occupied the region since early Recent times and appears to maintain a density fluctuating around relatively low levels. The ecology of the Sonoran collared peccary (D. t. sonoriensis (Mearns)) has been studied since 1956 by L.K.Sowls and his associates in Arizona. A number of publications have arisen from this research (Bigler, 1966; Brown, et a l . , 1963;; Neal, 1959a and b; Eddy, 1961; Kirkpatrick and Sowls, 1962; Sowls, 1961a, b; Sowls, et a l . , 1961; and Sowls and Minamon, 1961). These have included an extensive study of reproduction (Sowls, 1966). Several other reports, noteably those of Jennings and Harris (1953), Knipe, (1958) and Leopold (1959) have been concerned with the ecology of the collared peccary in Texas, Arizona, and Mexico, respectively. E l l i s o r and Harwell (1969) have recently studied the home range in the species in south Texas. Despite this previous work, Sowls1 (1961 a) statement that "one of the least known phases of the l i f e history of the collared peccary is it's rate of increase" was s t i l l largely true when I began my studies in 1964. This unknown sector included potential reproduction and survival of young in the f i e l d . The studies cited have shown that reproductive condition in the peccary does not occur in a predictable rhythm stimulated by seasonal changes in photo-period. Rather, being.an animal of tropical origin, i t s reproduction' i s geared to other environmental circumstances. The nature of 2. these proximal stimuli were not known. It is known that this species in Texas and Arizona produced young at any time of the year though there was indication of a seasonal concentration in the late spring. Sows were known to be capable of producing two l i t t e r s per year in captivity (Sowls, 1961a). More young at foot had been noted during periods following substantial rain-f a l l than during droughts. It has been strongly inferred therefore, that vegetation i s the proximate factor important to peccary populations in Texas that are ultimately controlled by r a i n f a l l . Rainfall in Texas i s highly erratic in distribution and amount, and the number of years in which i t is less than average exceeds that in which i t i s average or greater (Texas Agric. Ext. Serv., 1954). Thus the water resource on which plant growth depends fluctuates widely. Numerous studies in Texas have shown that plant growth decreases severely during drought. Wallmo (1957) showed that on the Black Gap Wild-l i f e Management Area even the most drought resistant species were severely damaged by drought. On the Welder Wildlife Refuge the important forage species of bunch-grasses have been known to suffer up to 77% mortality (Chamrad and Box, 1965). Thus the plant resource for support of herbivorous mammals fluctuates widely. The effect of r a i n f a l l on some animal populations i s marked. White-tailed deer on the Welder Refuge increased from 1145 deer, at the end of a drought (Knowlton, 1964), to 1600 (130 deer/sq mile) after 2 1/2 years of high r a i n f a l l and good range conditions (White, 1966), and decreased to 1150 (90 deer/sq mile) during a subsequent severe drought (Low, 1967). Similarly, Marburger and Thomas (1965) found that deer herds in central Texas can decrease as much as 44c/o during drought. Reproduction of wild turkeys on the Welder Refuge was also affected. Watts (1969) found that nesting by yearlings did not occur and many adults did not produce youngi during a year.of severe drought. Thus, droughts have a measurable impact on vegetation and through i t on entire animal populations. For vegetation, the effect i s direct, through insufficient moisture for plant growth and maintenance. The influence upon animals is primarily indirect, through limited forage and habitat availability, and to a minor extent direct, through decreased availability of drinking water. The purpose of my research was to examine reproduction in the collared peccary (Dicotyles tajacu anguiatus (Cope )) (Woodburne, 1968), livi n g in semi-desert conditions, and to assess the influence of r a i n f a l l on i t s reproduction and productivity. 3. In order to assess the impact of climatic conditions on peccary reproduction i t was desirable to compare populations l i v i n g under r e l a t i v e l y "optimum" conditions with those l i v i n g under harsh conditions. Southern Texas was chosen as the location for study of peccaries i n an "optimum" habitat because of r e l a t i v e l y high peccary populations and suitable f a c i l i t i e s . The western part of Texas i s generally harsher i n most regards - - less r a i n f a l l , colder winters, hotter summers, higher evap-oration rates, less vegetation — - than i s south Texas, and two s i t e s were chosen there f o r comparative study of peccaries. By chance, climatic conditions during the study made i t possible to compare reproductive performance i n the "optimum" south Texas area under both moist and dry climatic conditions and t h i s became the major comparison of the study. So that the populations of peccaries being studied i n the f i e l d could be put into the proper perspective, they were compared with animals raised on unlimited food in c a p t i v i t y . I have not been concerned with s o c i a l or other possible i n t r i n s i c mechanisms of population regulation. The probability of a long sequence of favourable years that would enable the population to reach densities at which such mechanisms would be l i k e l y to operate appeared to be s l i g h t . 2. STUDY AREAS My study was concentrated i n south Texas on an area assumed to represent the optimum of Texas habitat for the species. The major part of the study was conducted on the Santa Gertrudis Division of the King Ranch. A second area, the Rob and Bessie Welder W i l d l i f e Foundation Refuge, served as headquarters and provided supplementary f i e l d data. This second area i s a region of discontinuous peccarry habitat but has a r e l a t i v e l y high density of peccaries on suitable s i t e s . I selected two s i t e s i n a r i d west Texas where data on re-production of peccaries l i v i n g i n a harsher environment could be obtained for comparison with the south Texas data. These were the Watson Ranch and the Black Gap W i l d l i f e Management Area. 2.1. Physiography Figure 1 shows the approximate location of the four study areas i n Texas. The 203,000 acre Santa Gertrudis Division of the King Ranch i n south Texas i s centered around l a t i t u d e 27° 27'N and longitude 98° 02'W, just west of K i n g s v i l l e i n Kleberg, Jim Wells and Brooks Counties. The ranch i s bounded by sorghum, cotton, and watermelon f i e l d s and ranch-lands. The 7,800 acre Rob and Bessie Welder W i l d l i f e Foundation Refuge i s about 50 miles NNE of the King Ranch. I t i s centered at l a t i t u d e 28° 07'N and longitude 97° 22'W, and i s seven miles north of Sinton i n San P a t r i c i o County, The Refuge i s bounded on the north and east by the Aransas River and on the remainder by large c a t t l e ranches. Both of the areas are close to the Gulf of Mexico, approximately t h i r t y and s i x miles distant, respectively. The south Texas areas are both i n the Gulf Coastal plains region primarily a r o l l i n g to f l a t homocline consisting of nearly p a r a l l e l s t rata sloping gently to the Gulf of Mexico (Johnston, 1955; Thomas, 1962) The maximum r e l i e f i n both areas i s about 30 feet with the-base elevation varying from just above sea l e v e l to 150 feet. The s o i l s i n the area are calcareous sands and clays underlain by moderately indurate caliche at depths of two to 12 feet (Johnston, 1955; Oakes, et a l . , 1958; Kovar, 1963 Box, 1961). Drainage of the Coastal Bend areas i s effected by numerous small frequently temporary creeks which have carved sizeable valleys. However, surface drainage on the blackland clays and exposed formations i s very slow due to s o i l texture and lack of gradient, and occasional small pothol Black Gap ^ I c U i f / 6 Management Figure 1. Location of the study areas, and r a i n f a l l and evaporation distribution in Texas. = Rainfall (inches) = Evaporation (inches x = Station record, evaporation r a i n f a l l Mod. from Bloodgood, et a l . , 1954, and Thomas, 1962. 50 40 Rob and Bessie Welder Wildlife Foundation Refuge. Santa Gertrudis Division, King Ranch. TE X AS CJl 0 50 100 6. remain for considerable periods. Windmills, water tanks and earthen tanks are scattered over the areas at approximately 1 1/2 mile intervals. The two arid sites are both in west Texas (Fig. 1). The 13,120 acre Ralph Watson Ranch is centered at 30° 21'N latitude and 101° 25'W longitude in the Edwards Plateau region (Thomas,1962). It is approximately 15 miles east of the Pecos River and 25 miles SSW of Ozena in Crockett County, and is surrounded by other large sheep ranches. The approximately 100,000 acre Black Gap Wildlife Management Area i s centered at 29° 32' N latitude 102° 54' W longitude in Brewster County in the Big Bend area of Trans-Pecos Texas (Thomas, 1962). Its SE boundary is the Rio Grande and;: the SW boundary is the Big Bend National Park. Several large cattle ranches are on the northern boundary. On the Watson Ranch the original plateau is about 2200 feet above sea level, and wind and rain have carved extensive valleys and canyons down to a base elevation of 2000 f t . The soils are calcareous stony and clay loams underlain by caliche (Carter and Cory, 1932; Oakes, et a l . , 1958). Drainage is very rapid in the area, and streams seldom contain water except after r a i n f a l l . Windmills, water troughs and overflow ponds are located around the ranch for watering livestock. The Black Gap;Wildlife Management Area is exceedingly broken, with barren, rocky mountains and plateaus to 5600 feet surrounding f l a t basins and plains down to 1700 feet. The soils are calcareous clay loams and sands derived from limestone and igneous parent material (Wallmo, 1957; Oakes, et a l . , 1958). The Rio Grande is the only permanent stream in the area, and drainage is very rapid over the remainder of the area. Water tanks and catch-ment basins are scattered over the area to provide water for wildlife. The soils in a l l of the study areas are generally very f e r t i l e and require only water to support luxuriant vegetation. The west Texas soils con-tain much less clay and have a lower moisture holding capacity. No nutrients and known to be lacking in the soils over most of the area (Bray, 1901). 2.2. Climate The climatic elements important to peccaries are those that con-t r o l the growth and the persistence of the food resources and those affect-ing peccaries directly. Thus, r a i n f a l l , evaporation rate, temperature and s o i l moisture are important. Rainfall varies markedly in distribution and amount from year to year in Texas and variations in temperature, evaporation, and s o i l moisture are largely dependent on the r a i n f a l l . Therefore, r a i n f a l l is probably the single most important factor in the environment as i t affects peccaries through the influence of vegetation. Because i t was more p r a c t i c a l to obtain data on r a i n f a l l than on vegetative conditions, I concentrated on that aspect rather than on range productivity studies. The climate of south Texas i s semi-arid and megathermal, whereas the western areas range from semi-arid to arid and are mesothermal (Thorn-thwaite, 1948). Average temperatures are only s l i g h t l y warmer, but minimum temperatures are considerably higher i n south Texas (Table 1.). The daily fluctuations i n the west Texas s i t e s are more extreme. Table 1 shows the average maximum temperature i n July and the average minimum January temperature i n the two study regions. Fig. 2 shows the monthly average, minimum, and maximum temperatures for the four study s i t e s during the study period. It.-.should be noted that the winter of 1966-67 was colder than the previous two years i n south Texas. Table 1. Climatological characteristics of the four study areas. (Data from Belo Corp., 1965; Bloodgood, et^ a l . , 1954; King Ranch Inc., unpubl.) South Texas West Texas _Aug July max (°F) Aug Jan min (°F) Period of Frost (Days) Mean Annual pptn (inch) Mean Annual Evaporation (inch) Pptn/Evap. r a t i o Humidity Avg Welder Refuge 94 47 Dec 16-Feb 5 Dec 14-Feb 14 (62) 30.60 JCing Ranch 96 48 c (51) 26.50 97 (Laredo) 3:1 65-90 Watson Ranch 95 38 Nov 14-Mar 26 (132) 14.90 57.34 (Beeville) 84 (Dryden) 2:1 (Beeville) 5:1 65-90 48-54 Black Gap Area 100 32 Nov 9-Mar 31 (142) 11.35 99.80 9:1 28-50 Pr e c i p i t a t i o n throughout Texas i s highly e r r a t i c i n quantity, d i s -t r i b u t i o n , and time. (Figs. 3 & 4). Droughts occur about 1/3 of the time (Tex. Agr. Ext. S erv., 1954). Generally, rains are heaviest i n the spring and early f a l l i n south Texas, and i n the summer i n west Texas. The south Texas areas receive about twice as much rain as the west Texas areas (Table 1, Fig. 1), consequently vegetation production i s considerably higher and peccary densities there are greater. 1965 1966 1967 F i g . 2. Monthly average, maximum, and minimum temperatures f o r the four study areas during the study. The p o r t i o n i n black represents f r e e z i n g c o n d i t i o n s . Figure 3. Deviation of monthly r a i n f a l l ( S ) from the long-term monthly average ( d ) on the King Ranch and the Welder Refuge. 10. BLACK GAP ~ 4-z < te. Figure 4. Deviation of the monthly r a i n f a l l ( Q ) from the long-term monthly average [{~} ) near the Watson Ranch and the Black Gap Management areas. 11. A definition of drought appears appropriate. Drought i s a complex concept and is d i f f i c u l t to measure objectively. The only definition that is generally accepted is that i t is a severe shortage of water. (Gibbs and-Wlaher,1967). The determination of "shortage" requires definition relative to the object of interest. In relation to plants, i t occurs when there i s insufficient water present in the s o i l to enable plant growth to take place (Carrodus, 1967). In relation to herbivores, i t occurs when water is so defficient as to result in a shortage of forage (R.A. Perry, pers. comm.). Generally speaking, the biota i s generally adapted to a r a i n f a l l level near normal, consequently, sig-nificant departures from normal can seriously influence the biota. Several methods of measuring drought have been used. In Texas i t i s .generally "accepted thatfwhen.the annual r a i n f a l l i s less than 70% of the mean annual r a i n f a l l , a drought situation exists'(Texas Agric. Extension Serv.,1954). Several authors have stated that the amount of r a i n f a l l i s the best single indicator of drought (Gibbs and Maher,1967; Slatyer,1962). A better indicator of degree of drought i s an index using r a i n f a l l and evaporation, although such measurements have no bio-logical component. Newsome (1966a) has proposed one method of objectively determining the severity of drought by using evaporation, r a i n f a l l , and the amount of r a i n f a l l that effectively causes a response of vegetation as determined by Slatyer (1962:121) for central Australia. I have used a similar measure to determine the degree of aridity. Although central Australia receives an average r a i n f a l l about 1/3 that of south Texas, the amount of r a i n f a l l required to i n i t i a t e growth in plants is probably similar. My limited observations of plant growth after r a i n f a l l in south Texas indicate.this i s not an unreasonable assumption. In calculating an aridity^index, the effective r a i n f a l l required to i n i t i a t e plant growth during the hottest 6 months (Miay-Sept.) was assumed to be 1 inch. During the coolest 6 months (Oct.-Mar.') i t was assumed to be 0.5 inch. The aridity index was determined by subtracting the average daily open-pan evaporation from the daily r a i n f a l l . When r a i n f a l l sufficient to i n i t i a t e plant growth occurred, the index was reset to that amount on the positive side i f the index had been negative, and added to the index i f i t had been positive. Subtraction of daily evaporation continued until the next r a i n f a l l . If the r a i n f a l l was insufficient to i n i t i a t e plant growth, the amount of rain was added to the aridity index. The graph of the accumulated rainfall-evaporation data i s shown in Fig. 5. Also plotted on the graph are the approximate periods favourable to plant growth, March to F i g . 5. A r i d i t y index f o r the Welder Refuge (south Texas). A. Ar i d i t y compiled using daily r a i n f a l l records. B. Monthly summary of a r i d i t y using monthly t o t a l s . Sur.= surplus moisture; Mo.Ave. = average monthly r a i n f a l l f o r 10 years at Welder Refuge; Dr. =.drought, r a i n f a l l d e f f i c i e n t or near def f i c i e n t for plant growth. [TTT1= major plant growth periods ]= secondary plant growth periods 14. June and mid-September to October. During the study period, slight drought conditions prevailed through 1964 to May, 1965 in south Texas, but good rains in February, 1965 provided sufficient s o i l moisture to i n i t i a t e and sustain spring plant growth until the May rains broke the drought (Fig. 5). Precipitation, on both the King Ranch and Welder Refuge, was above average for the last half of 1965 and Spring of 1966 (Figs. 3 and 5), and plant growth was luxuriant over the winter. Drought conditions started again in mid-1966, and became extreme by September, 1967 (Orton, 1967) when they broke with hurricaneBeulah. Growth of vegetation was very poor during the normal autumn and spring growing periods in 1966 -67. In west Texas precipitation was below average in 1965 and above average in 1966 (Fig. 4) and range conditions reflected the differences. 2.3. Vegetation Thomas (1962) and Gould (1962) have summarized ecological conditions in Texas and list e d the plants. In general, the vegetation in south Texas is much denser than in the more arid west Texas areas (frontis-piece and Plate l ) . The Welder Refuge l i e s in a transitional area between the South Texas Plains and the Gulf Prairies and Marshes of Thomas (1962) and is in Dice's (1943) Tamaulipan Biotic Province. A l i s t of s c i e n t i f i c names of plants i s given in Appendix A, and the s c i e n t i f i c names are used in the text only where necessary to avoid confusion. Peccaries were mast commonly observed on the clay loam and sandy loam sites and not infrequently on the bottomland sites. The clay loam sites support chaparral-bristle grass, prickly pear-shortgrass and huisache-buffalograss communities. On the sandy loam soils, huisache—bunchgrass, colubrina-bunchgrass, chittimwood-hackberry, and li v e oak-chaparral com-munities were frequented by peccaries. Both communities of the bottomlands, hackberry-anacua and the woodland-spiny aster complex, were used frequently for cover and feeding. The plant communities of the Welder Refuge have been described in detail (Box, 1960,1961; Box and Chamrad, 1966). The King Ranch l i e s primarily in the south Texas Plains and partly in the Gulf Prairies and Marsh Vegetational Areas (Thomas, 1962) and in Dice's (1943) Tamaulipan Biotic Province. The Santa Gertrudis Division i s included in Tharp's (1939) Mesquite-Chaparral Region except for the strip of 15. Plate 1. Representative peccary habitat in south Texas and west Texas. a. One-year old root-plowed chaparral-prickly pear community on the King Ranch in south Texas. Note the mature mesquite brush row on the horizon, and sparse huisache, and grassy areas in the foreground. The prickly pear in the center is 2 to 3 feet high. Peccaries feed out into the root-plowed areas and shelter in the brush rows. b. Several-year old root—plowed chaparral—prickly pear community on the King Ranch. Note the height and density of the mesquite, huisache, and granjueno bushes. The prickly pear is 3 to 4 feet high. c. A densely vegetated community of the lowland desert scrub association on the Black Gap Wildlife Management Area ih west Texas. Note the lechuguilla, chinograss, and whitethorn, and the extensive bare areas. The lechuguilla i s an important food source for peccaries in west Texas. 17. sandy s o i l stretching across the southern tip of the Division which i s in the ecatone between Coastal Mainland Dunes Region and the Mesquite-Chaparral Re-gion. Johnston (1955) discusses the vegetation and the edaphic and c l i -matic factors involved in the areas. The communities of the King Ranch are similar to those of the Welder Refuge, but the chaparral-bristlegrass com-munity i s more extensive over most of the Santa Gertrudis Division. In the sandy south end of the Division the prairie bunchgrass—annual forb community replaces the chaparral. Nopal prickly pear (Opuntia lindheimeri) i s far more common over most of the Division than i t i s at the Refuge. Peccaries were most numerous in the prickly pear dominated brush communities. The dominant species in the brush community i s honey mesquite, vary-ing in height from shrub to tree form. Several acacias, blackbrush, huisache, twisted acacia, prickly ash, granjueno, agarito, lotebush and sapote are also quite common in the brushy areas. Prickly pear cactus and ta s a j i l l o , or jump-ing cactus, are widely distributed and common in the brush.' Forbs and grasses are sparsely, but widely, distributed in the deep brush communities, but become the dominant forms in the prairie areas scatter-ed through the brush and on the loose sandy areas at the south end of the Division. Seasonal aspects are evident in the forbs. Among the species are hairy tubetongue,dwarf ayenia, iceweed and lyre-leaf parthenium. Grasses are very numerous; 218 species are recorded for the Coastal Bend region with Andro— pogon, Panicum, Paspalum, Eragrostris, and Stipa being the major genera (Gould and Box, 1965). Distribution of the chaparral on the King Ranch has been extensively changed by brush control practices. Through the use of a 'rootplowing' tech-nique (Box and Powell, 1965), large areas are cleared of brush with the usual result that prickly pear is widely scattered, and roots quickly. It becomes a dominant species and provides emergency food for livestock. Grasses and forbs also establish quickly. Brush strips are l e f t at about 1 1/2 mile intervals and along creek beds, roads, and fences to prevent erosion and to provide shade and cover for livestock and wildlife. The intervening areas are rootplowed every 12 to 15 years when the brush has replaced the cactus and herbaceous plants (Mr. Wilkinson, pers. comm.). The overall pattern i s one of blocks of prickly pear-bunchgrass communities (in varying proportions of each) in various successional stages of brush invasion separated from each other by strips of mesquite-chaparral (Plate l a and b) . 1 8 . The Watson Ranch i s located in the Edwards Plateau vegetational area of Thomas ( 1 9 6 2 ) . Tharp ( 1 9 3 9 ) divided the Edwards Plateau into four vegetational regions, and described several plant communities in the area of the ranch (.Tharp, 1 9 4 4 ) . On the mesa tops, a sotol-bunchgrass community exists. In the canyons and valleys are scrub forests, chapparal-bunchgrass, and occasional li v e oak-hackberry mottes, with extensive open areas of bunchgrasses and forbs. Bare s o i l and rocks are much more extensive than in the south Texas areas. Prickly pear (Opuntia lindheimeri and 0 . engelmannii), sotol, and lechuguilla are scattered throughout the area and forbs are plentiful following rains. The Black Gap Management Area i s located in the highly variable Trans-Pecos vegetation area of Thomas ( 1 9 6 2 ) . Wallmo ( 1 9 5 7 ) recognized two major groups of vegetation types in the Big Bend, the Lowland Desert Scrub Associations and the Mountain Bush and Woodland Associations. In the lowland areas with l i t t l e vertical variation and no abrupt changes in altitude, the whitethorn-creosote bush-lechuguilla community dom-inates. Creosote bush i s the dominant plant with lechuguilla, whitethorn, prickly pear (principally Opuntia engelmannii) t a s a j i l l o , ocotillo and sotol (Dasylirion leiophyllum) more or less densely scattered throughout. Wallmo ( 1 9 5 7 ) found the "ground vegetation" covered an average of only 1 0 . 5 ° / o and the "canopy" 1 8 . 3 ° / o of the total plot area. On the upland sites and lowland areas where moisture conditions are more favorable (in draws, at edges of rock caps, etc.), the more densely vegetated sotol-lechuguilla-chinograss communities dominate. Sotol, yuccas, chaparral, species such as whitethorn, mesquite, black-brush, catclaw, guajillo, ocotillo, creosote bush, tarbush, several junipers, and prickly pear are the predominant "canopy" plants. Chinograss, sand bur (Cenchrus myosuroides), lupins, lechuguilla, goldeneye, croton (Croton neomex-icanus), and others make up the ground vegetation. 2 . 4 . Competitors and predators Blair ( 1 9 5 0 ) l i s t s the animals characteristic of each of Dice's ( 1 9 4 3 ) biotic provinces in which the study areas are situated. The s c i e n t i f i c names of the mammals cited are given in appendix A. Mammalian herbivores important to the south Texas area are cattle, deer, cottontails, jackrabbits, and a variety of rodents, notably the cotton rat and the southern plains woodrat. On the Refuge there are 4 0 0 tp 5 0 0 steers? 19. about 40 animals/sq mile, while on the King Ranch, the density is a l i t t l e greater. Whitetailed deer populations here are second in density only to the Central Mineral Basin of Texas (Teer et a l . , 1965; White, 1966). On the Refuge, the population varied between 1100 and 1600 animals, or from 91.4 to 133.3 deer/sq mile (White, 1966). On the King Ranch, the population has been conservatively estimated at 31.5 deer/sq mile (Kiel, 1963). A variable number of feral pigs range over parts of the Welder Refuge, but the density i s usually kept low by constant hunting. No feral pigs were present on the Santa Gertrudis Division of the King Ranch despite a relatively high density on the Laurelos Division a few miles to the east. Important carnivores in the area are the coyote, bobcat, grey fox, badger, and raccoon. Coyotes are f a i r l y common on both areas, despite the fact that populations on the King Ranch are controlled and those on the Refuge are not. White (1966) estimated 25 to 40 on the 7,800 acre Welder Refuge in 1965, and the density i s similar or higher on the King Ranch due primarily to the higher rodent populations liv i n g in the more extensive prickly pear com-munities. In 2 1/2 years, 959 coyotes and 158 bobcats were removed from the King Ranch without apparently altering the density of the two species (King Ranch trapping records, unpubl.). Between 2,000 and 3,000 sheep are kept on the Watson Ranch. This i s between 98 and 146 sheep/sq mile, which i s about average for the county (Teer et a l . , 1965:19). Several cows and horses are also kept on the ranch. An unknown number of deer range the area, but an estimate for an adjacent area places the density at 9.6 deer/sq mile (Teer _et a l . , 1965). Coyotes, bobcats and mountain lions have been eliminated from this sheep ranching area, so that predation on peccaries i s virtually absent. Livestock were removed from most of the Black Gap area in the early 1950's, and only along the Rio Grande valley bottomlands do horses and goats trespass. Mule deer have been extensively studied on the area and densities of 11.0 to 16.4 deer /sq mile were estimated from pellet groups (Wallmo, 1959). During the two years that I collected data on the area, the population estimate increased from 22.1 to 22.7 deer/sq mile (Hailey, 1966; Brownlee, 1.967). Approximately 100 pronghorn antelope range over the northern and western por-tions of the area. Jack rabbits, cottontails and numerous rodent species are present. Coyotes, bobcats and mountain lions are not generally controlled on the Black Gap area, but densities are not high. Grey fox and badgers are also present in varying number. 20. 3. METHODS and MATERIALS The methods employed i n the study were designed to obtain data on the effect of climate and climatic changes on reproduction and productivity of peccaries. The i n i t i a l approach was to compare reproductive performance of animals under a presumed optimum regime i n south Texas and under a harsher climatic regime i n west Texas. By chance, circumstances during the study made i t possible to compare the population i n the "optimum" south Texas area under both moist and dry climatic conditions and t h i s became the major part of the study. A series of animals was raised i n c a p t i v i t y to provide a standard against which reproduction i n the natural population could be compared. Headquarters - were established at the Welder Refuge with a temporary headquarters at the King Ranch Santa Gertrudis Division. From these locations frequent t r i p s were made into the f i e l d to observe and c o l l e c t peccaries. After an exploratory period of three months, July to September, 1964, c o l l e c t i o n of .data i n south Texas began i n February, 1965, and terminated i n August, 1967. Seven t r i p s were made to the Watson Ranch over the period from November, 1965 to July, 1967, to observe and c o l l e c t peccaries. Two t r i p s were made to the Black Gap area to obtain data from hunter—killed peccaries during the annual hunt i n l a t e November of 1965 and 1966. An additional t r i p was made to the Black Gap area i n February, 1967, i n an attempt to obtain supplementary data. The primary means of obtaining data on reproductive performance was to c o l l e c t animals at in t e r v a l s frequent enough to assess the reproductive con-d i t i o n of the population. Additional data on reproduction were obtained from pen—reared peccaries and from live—trapped peccaries. Data on survival and recruitment were obtained by observation of both marked and unmarked animals. 3.1. Collected animals Altogether, 153 peccaries were collected i n south Texas, during the period March 1965 to August 1967.. Seven were from the Welder Refuge and 146 from the Santa Gertrudis Division of the King Ranch. Most of the animals were k i l l e d with a r i f l e (high.power and .22 c a l i b e r ) , but some were caught by the U.S. Fish and W i l d l i f e Service predatory animal trapper i n double spring st e e l traps set f o r coyotes and bobcats. Several specimens were obtained from l i v e - t r a p accidents and road k i l l s . I collected 17 peccaries on the Watson Ranch with a r i f l e . Hunters brought 119 peccaries through the check station on the Black Gap Management Area and from these I obtained reproductive data on 32 females and 48 males. 21 . During the i n i t i a l phase of the study, an attempt was made to se-lectively collect adult females, but d i f f i c u l t y of rapid sex determination in the f i e l d proved this to be impractical. From July, 1965, the collections were more random, but i f sex could be determined readily, females were taken preferentially. Animals judged to be immature were generally not collected unless collection of a complete herd was attempted. The following data and materials were obtained during autopsy of the specimens from south Texas and the Watson Ranch: date; time; location, and means of collection; habitat; sex; age; weight and measurements; general condition of pelage and skin abnormalities; ectoparasite and endoparasite loads; blood serum for arbovirus assay; weights of body organs; kidney fat estimate; eye lenses; skull and lower jaw; reproductive state; and a stomach sample taken from the rumen portion of the subruminant stomach. From females, the reproductive tract was weighed entire; the number, location, sex, weight and crown-rump measurement of foetuses were determined and the foetuses pre-served; each ovary weighed and preserved; the mammary gland was weighed and lactation condition noted. From males, the testes were weighed and one or both preserved. From animals k i l l e d by hunters on the Black Gap area, body measure-ments, and carcass weight were taken along with the lower jaw and reproductive tract i f the hunter permitted or brought the parts in. On several animals complete autopsy, as for the south Texas specimens, was possible. Twentyfive peccaries which had been pen-reared were also autopsied and the same data as for south Texas animals taken. 3.2. Live-trapping The live-trapping program was carried out during the periods of September, 1964, and April, 1965 to July, 1967 on Mesquite Pasture on the King Ranch and on the Welder Refuge. Most of the peccaries trapped were caught in wooden deer traps 4 f t x 4 f t x 8 f t (Glazener, 1949) f i t t e d with a 1 inch x 2 inch mesh wire floor, and a drop gate. Cottonseed pellets were used for bait. The trapline was usually run early in the morning and reset immediately. Most of the animals were caught in the early evening. On the King Ranch, nine traps were operated in seven locations that were changed twice during the study. Usually trapping was conducted over a one week period once a month. However, during the f i r s t year of the study, the trapping intensity was higher in an effort to get a large number of animals marked early in the study. During the last ,8 months, trapping was concentrated 22. on the Welder Refuge. Trapping was initiated on the Welder Refuge in January, 1966, and a variable number of traps (up to five) were operated on an irregular basis until July, 1967. Peccaries caught in double spring steel traps in the marked-animal study area were also tagged and released. The method of handling the animals i s treated in Appendix B. The following data were recorded on the trapped animals: location, external characteristics, associates, relationships of animals within the traps, and age as adult (old, prime, young), juvenile (6 to 12 months), 1/2 grown (3 to 6 months), and red young (birth to 3 months). On subsequent recaptures, date,location, and associates were recorded. When f i r s t trapped, the animals were individually marked with ear tags, and some were f i t t e d with a harness. An individually patterned, colored vinyl-coated nylon streamer (Armor-tite, Cooley, Inc., Pawtucket R.I.) was held in place with a numbered button tag (Knowlton, et a l . , 1964) in the right ear of females and the l e f t ear of males. A numbered self-piercing strap tag was placed in the other ear. I n i t i a l l y , a l l adults were also marked with a harness modified from Bigler's (1966) design. The modification has two dorsal straps. Females were marked with a yellow rope harness, and males with a red rope harness. It was found to be unsatisfactory: unless it. was put on very tight, i t allowed tha animals to s l i p out of the harn ess, and i f i t was very tight, the breast and' shoulder straps cut into the animal. Three animals collected 12 to 22 months after being tagged had the polyethylene rope cutting well into the sternum with bone attrition on the inside and deposition on the outside. Within a month a captive animal f i t t e d with a harness had developed a suppurating wound under the dorsal strap and had started to limp. Several animals were f i t t e d with radio transmitter collars operating on Citizens Band frequencies. The equipment was modified from that described by Inglis, _et a l . , (1968) and Cook _et a l . , (1967). I periodically located the animals through use of a loop antenna and noted their location and attempted to determine their associates and activity. A total of 171 peccaries were marked, 19 on the Welder Refuge and 162 in the north end of Mesquite Pasture and adjacent pastures on the King Ranch. 3.3 Field Observations In conjunction with the other f i e l d operations, records were kept of a l l peccaries observed. The animals seen were classified as to seX and age: adult, 6-12 months old (juvenile), 3-6 months old (1/2 grown), and 0-3 23. months old (red young) i f possible. The time and location of the sighting was no3ted and activity recorded. Marked animals were identified i f possible and recorded. 3.4. Pen-reared animals At the University of British Columbia, peccaries were kept in individual pens 4 f t wide x 8 f t long with walls 4 f t high constructed of cement blocks. The pens were housed in a building that could be heated in the winter. Free-running water was available at one end of the pen and a food hopper was placed at the other end. A concentrated pelleted cereal ration (UBC 36-57) (Wood, et a l . , 1961) designed for deer was fed ad  libitum and the amount consumed was measured. Even though fed ad libitum, the animals did not become obese, but remained in good condition, the young were l e f t with the sows until they were weaned at two to three months. They had access to the pelleted food as soon as desired. During breeding t r i a l s , the females were taken from their pens and placed in the pen of the boar. This eliminated much of the aggressivness of the females, and particularly diminished the aggressive response of a.new mother. The females were allowed to remain in the pen with the boar for 15 to 20 minutes. As Sowls (1966) has shown, most of the mating took place in the f i r s t five minutes i f the female was receptive. The females were placed with the males usually two or three times a week, unless the sow was thought to be pregnant. Several sows were presented to the boar immediately after parturition, and daily for two weeks before going back to the regular sched-ule. The animals were weighed at intervals in keeping with their growth stage, progressing from weekly for very young to monthly for adults. Peccaries at the Welder Refuge were maintained in shaded, chain-link wire pens open to the elements. They were usually allowed to run together in one large pen. They were fed commercial hog pellets at a rate of about 2 lbs per day per adult. On this slightly restricted diet they did not get overly fat. Water was freely available. The Welder Refuge penned animals were periodically weighed, mea-sured and tooth progression noted, and on some, dental impressions taken. 3.5. Age determination Ages of the collected animals were determined by tooth eruption pat-terns in animals less than 24 months old, and from annulations in the cementum 24. of the f i r s t incisor of animals older than 24 months. The tooth eruption.pat-terns were developed from captive animals and the tooth annualtions from pec-caries pen-raised in Arizona, at U.B.C., and the Welder Refuge. Ages of trapped animals were determined from tooth patterns and body size. Ages of foetuses were determined by comparison with growth patterns of foetal pigs (Ullrey, et a l . , 1965) and deer (Thomas, 1970), and from the formula developed by Hugget and Widdas (1951) where a = .092 and t5 = 38 days. The development of the age determination techniques is shown in Appendix C. 3.6. Sex determination Male and female peccaries are morphologically very similar. Males have slightly shorter and more massive rostrum and lower jaw (unpublished data), but these are d i f f i c u l t to detect in the f i e l d . Urogenital organs and behaviour provide a clue to sex of free-ranging animals. On the male, the scrotal sac i s devoid of hair and protrudes slightly to the rear. On adults, the testes make a f a i r l y obvious swelling, but both sexes of young animals appear similar. The preputial opening is usually surrounded by a tuft of hair, but this character also i s not completely reliable because female occasionally have a tuft of hair protruding in the central abdominal area. On females, a distended udder can be detected with some d i f f i c u l t y . Behaviour i s frequently indicative of sex. Urination posture of the females is characteristic, and frequently location of the urine on the ground beneath the animal indicates the animal's sex. Observation of nursing was also a useful criterion. Sociality can also be used with high probability to determine sex. Frequently animals that were by themselves were older boars. Of 131 obser-vations of obviously solitary animals, 88% of the 67 animals sexed were males. There i s some bias towards males because i t i s possible to dis-tinguish whether the scrotum was present from greater distance than i t was possible to determine absence. 3.7. Census During the f i r s t year of the study', a census line was operated in conjunction with the trap routes. This was discontinued as the results did not appear to be r e a l i s t i c . Population fluctuations may be determined more accurately by watching fluctuations in individual herds, although Day (1964, 1965, 1966) has found the technique to be unreliable where populations are hunted. 25. 3.8. Food habits The stomach contents of 73 peccaries collected on the King Ranch over the study period were analyzed to determine species composition. A sample was taken from the globular central chamber (Moir, 1958) of the three-parted subruminant stomach and preserved in 1Q°/o Formalin. The samples were examined by the procedure outlined by Chamrad and Box (1964) to determine the percent volume of the component species. 3.9. Growth Growth patterns were established from pen-raised peccaries and from wild peccaries whose age was determined from tooth eruption or annuli. Pen-raised animals were weighed at weekly intervals until they reached 2 to 3 months, then biweekly to 4 or 5 months, and monthly after that. Foetuses were weighed and the crown-rump length taken from forehead to posterior-most part of the rump, with the vertebral column straight, and the head at right angles to the vertebral column. On some postnatal young, crown—rump measurements were taken for comparison with foetal young. Wild peccaries less than 20 lbs. were weighed to the nearest 1/lOth pound, and animals over 20 lbs. were weighed to the nearest pound. If the animal had been bled, an arbitrary 5% was added to the weight to obtain a l i v e weight (Prosser and Brown, 1950). Standard body measurements were taken with a flexible steel tape. They were: total length, hind foot length, and ear length, (from notch) shoulder height, chest girth, and, on some animals, neck girth. Total length was measured along the dorsal contour while the head was in a natural position. Shoulder height was measured from the toe and followed the contour of the shoulder to the vertebral column (Teer, et a l . , 1965). Chest girth was measured only on animals whose brisket had not been cut. For this reason, few of the hunter—killed and gutted peccaries were measured for this character. The standard error of the measurements was: total length + .19 inch, hind foot length + .05 inch, ear + 0 inch, shoulder contour height + .22 inch, chest girth + .63 inch. Carcass weight i s preferred as a measure of animal weight because stomach and uterine contents of l i v e animals cause l i v e weights to vary excessively. Live weight of adult south Texas peccaries i s related to car-cass weight according to the regression, y (live weight) = 1.45x + 1.3, with 26. a highly s i g n i f i c a n t correlation c o e f f i c i e n t (r = .98, d.f. = 67) f o r males, and y = 1,67x - 2.3 (r = .94, d.f. = 69) for females. The lower 'r' for the females i s due to variation caused by pregnancy-related weight changes. 3.10 Condition I assessed animal condition by estimating the proportion of each pair of kidneys covered by f a t and assigning a Kidney Fat (K.F.) index of G> l/4> 1/2, 3/4, 1, or between these values. 3.11 Male reproduction Testes used i n the analysis were obtained from the King Ranch, Watson Ranch, Black Gap Area, and from pen-reared animals. A l l testes except the Black Gap samples were usually stripped of the tunica and epididymis, weighed, volumes determined, s l i t and preserved i n 10% Formalin. The testes from Black Gap specimens were usually preserved p r i o r to weighing. I f the testes i n each pair were approximately the same size and morphology, only the l e f t t e s t i s was preserved. After preservation f o r varying periods of time, the testes were blotted dry and weighed to 0.1 gm. Volumes were determined to 0.1 ml with a modified manometer. A series of 41 testes representing various growth stages of testes of young peccaries, and normal and extremely low weights of adult testes collected through the year were randomly selected f o r detailed h i s t o l o g i c a l examination. One abnormal pair of testes.was also examined h i s t o l o g i c a l l y . Several authors (Parkes, 1965; Simard, 1964) have shown that a cross-section of the testes from almost any area i s representative of the whole. To ascertain t h i s , I.examined cross-sections from three areas evenly spaced along the long axis of several testes. On the remainder of the selected testes, a cross-section from only the mid-portion of the organ was h i s t o -l o g i c a l l y examined. The formalin-fixed sections were post-fixed i n Bouin's solution, embedded i n wax and two or three B p sections cut on a rotary microtome and mounted for staining. Staining procedures followed Humason (1967). A modified Masson's Trichrome s t a i n , (Weigert's Haematoxylin, Acid Fuchsin - - Ponceau 2R, Aniline Blue - - Orange G) was used for general staining (Humason, 1967). Some sections were stained with Periodic-Acid-S c h i f f Reagent (Humason, 1967) i n order that the P.A.S. positive spermatozoa could be more easily counted. 27. Testicular anatomy and inferred physiology were compared using t e s t i s s i z e , seminiferous tubule diameter, spermatogenic a c t i v i t y , spermio-genic a c t i v i t y , and proportion of t e s t i s composed of seminiferous tubules and i n t e r s t i t i u m . Testis size was standardized against hind foot length to remove seasonal and age va r i a t i o n . (Hind leg reaches adult size at about 1 year: Appendix D) . The formula f o r determining the index of testes size i s : T . . T , /--r-r-i mean of paired t e s t i s weights . , , . Testis Index [TI = , .—\, „ , -, rr, fi . A monthly reproductive 1 hind foot length 7 ^ index was calculated by taking a l l collected males 2 years and over (sexually and physically mature) and averaging the indices. Growth of tes-tes from immature to mature stages was determined by averaging the indices of a l l animals i n the same age groups. Diameter of the seminiferous tubules was determined by taking the mean of f i v e cross-sectioned tubules randomly selected from a sub-peripheral area at r e l a t i v e l y equal i n t e r v a l s around the periphery of the t e s t i s . I assessed spermatogenic a c t i v i t y by microscopic examination of several f i e l d s of a t e s t i s cross-section at suitable magnification, and c l a s s i f i e d the spermatocytes and spermatids as numerous, moderate or few. Sperm were counted i n the f i v e previously selected cross-sectioned tubules, at 1250 X magnification ( o i l immersion). The proportion of the t e s t i s com-posed of tubules was determined with an ocular microscopic g r i d of 20 squares to a side oriented over the t e s t i s section at s u f f i c i e n t magnification to allow the gr i d to f i t just inside the t e s t i s cross-section. Five rows of 20 squares were then examined, and the squares c l a s s i f i e d as the material (tubule or interstitium) making up the greatest proportion of the square. The number of squares out of the 100 t o t a l gave the percent of the testes that were tubules, and the complement of that was assumed to be the i n t e r -stitium (including secretory c e l l s , connective tissue, blood vessels, se-cretion sinuses, etc.). 3.12 Female reproduction Data on reproduction were obtained from females collected i n south and west Texas, and from pen-reared animals. The i n d i v i d u a l l y numbered ovaries were preserved i n Bouin's solution (Humason, 1967) for subsequent analysis. A representative selection of the various stages of development of the uterus were preserved i n 10% Formalin. The mammary gland was cut open to determine the state of l a c t a t i o n , and then discarded. I f the sow 28. was pregnant, the foetuses were weighed, crown-rump measurements taken, and then preserved i n 10°/o Formalin. From the Black Gap specimens, generally only the ovaries were obtained. These were preserved i n Bouin's solution as soon as they were obtained, but they could have been collected by the hunters up to 36 hours before preservation. Some reproductive tracts were examined, and several preserved i n 10°/o Formalin. No foetuses were brought i n by the hunters, although two pregnant sows were reported in 1966. A t o t a l of 73 pairs of ovaries were collected from south Texas specimens, 8 pair from Watson Ranch specimens, 17 pair from Black Gap specimens, and 9 pair from pen-reared specimens with documented reproductive history. After storage i n Bouin's solution f o r up to 3 years, the ovaries were reweighed to 0.1 gm, volume determined with a modified manometer to 0.1 cc, and measurement taken of the external dimensions of the ovary and protruding corpora lutea. Bouin's solution was removed with several baths of 70c/o ethanol p r i o r to embedding i n wax. Embedding the large ovaries with large corpora lutea proved d i f f i c u l t u n t i l I found that a s c a l p e l -cut to the heart of each corpus f a c i l i t a t e d penetration of the clearing agent and wax. The ovaries were double embedded by clearing f o r up to 4 days i n methyl benzoate u n t i l the ovaries became translucent. They were then transferred to benzene for 1/2 hour and embedded i n three changes of Paraplast according to standard technique (Humason, 1967). S e r i a l sections of the ovaries were taken on a rotary microtome at 8 JJ and every 12th section mounted consecutively on labe l l e d , albumenized glass s l i d e s . Most of the ovaries from pen-reared peccaries were sectioned at 8 JJ and every 10th section mounted. Thus, in the f i r s t case, one section from every 96 JJ of ovary was mounted, and i n the second case, one section from every 80 p was mounted. Because the'oocytes are-.about 120 p diameter, every oocyte should have been represented on the s l i d e s . The sections were stained i n a modified Masson's trichrome stain (Humason, 1967:166) which included Weigert's haematoxylin, Acid fuchsin — Ponceau 2R, and a n i l i n e blue - - Orange G, and covered with Permount and a coverslip. Corpora lutea, Graafian f o l l i c l e s , larger scars, medulla, cysts and the ovary i t s e l f , were measured at t h e i r largest diameters with an ocular g r i d on a binocular dissecting microscope. The number of sections containing 29. portions of the structure were counted and multiplied by the appropriate section frequency and thickness to obtain the t h i r d diameter. The mean diameter of these structures was obtained by adding the three diameters and dividing by three. Volume of the structures vwas determined from the formula V = 4/377"^ r r ^ where r^ , r^> and r ^ are the three r a d i i . Shrink-age of ovaries between co l l e c t i o n and s l i d e preparations averaged 32.1°/o. The sections were scanned at 25X with the dissecting microscope and scars, f o l l i c l e s greater than 1.5 mm i n any dimension, and cysts counted. A compound l i g h t microscope at appropriate magnifications was used for detailed examination of structures. 3.13. S t a t i s t i c a l treatment S t a t i s t i c a l comparisons between sample means were made using Bailey's (1959:172) method where samples are small, variances are not assumed equal and sample sizes are not the same. Most graphic comparisons are made using the mean, 95°/o confidence i n t e r v a l and range unless fewer than four samples are present, i n which case the 95°/o confidence i n t e r v a l i s not shown. The 95P/0 confidence i n t e r v a l i s usually abbreviated S.E. t.05 in the figures and tables as mentioned by Steel and Torrie (1960:46). 30. 4. RESULTS 4.1. Food habits Samples of the stomach contents were obtained from 73 pec-caries over the 2 1/2 year period from February, 1965 to August, 1967. The samples contained an average of 63% prickly pear, 18% grass species, 7% forbs and small amounts of animal matter and unidentified plant fiber. On. a seasonal basis over the study, the composition varied markedly (Fig.6). Throughout the year prickly pear made up the greatest portion of the diet, but during the late spring and summer, when they were available, the flowers and f r u i t were taken in preference to the cladophylls. Grasses made up 25% of the diet during the spring, 14% during the summer, and 10% during the f a l l . Forbs were taken in preference to other plants as soon as they became available, and because of the seasonal progression in forb species, the total proportion in the diet changed l i t t l e . Variation in food availability associated with precipitation was also present. In 1965, spring rains followed a two year drought, and resulted in an i n i t i a l profusion of annual forbs. Perennial grasses were slower in following, but after a year of good rains, grasses had increased in abundance. The hot summer in 1966 caused browning off of a l l herbaceous material, despite modest amounts of rain, but the cooler autumn conditions enabled some forbs to grow. The drought over the winter effectively pre-vented forage growth. However, perennial grasses were able to take advantage of the below average rains that did come during the spring, 1967, and initiated spring growth. Lack of rain prevented continued development. Forbs were very scarce during the spring. These differences in abundance of the forage classes were reflected by peccary food habits. Prickly pear cladophylls were constantly available, and when l i t t l e other food was available, prickly pear became the dietary staple. This situation occurred during the f a l l and winter of the 1966-67 drought (Fig. 6). 4.2. Condition The kidney fat index (K.F.) was the most consistent indicator of general nutritive condition. A K.F. index of less than 1/8 was associated with very l i t t l e body or mesenteric fat. Very few animals ever had a K.F. index over 3/4. Figure 6. Forage class composition of the stomach contents of 73 collared peccaries ^ from south Texas. Spring includes the period February to May, summer includes June to Ausgust, and f a l l includes September to November. % VOLUME 100 -Animal matter SUM MOIST DROUGHT 33. The animals pen-raised at U.B.C. had up to 3/4 inch of rump fat on them, yet had K.F. indices between 1/2 and 3/4. Juveniles usually had a low K.F. index between 0 and 1/8 unless they were in a season of exceptionally good food quality and quantity, as in the summer and f a l l of 1965. New born animals usually had a K.F. index between 1/4 and 1/2. There was no significant difference between K.F. indices of males and females, although females in the last half of gestation tended to have a slightly higher index. The amount of fat present on the kidneys showed'a distinct seasonal pattern (Fig. 7). During late winter and early summer, the K.F. indices were low. Adults put on some fat stores during the spring vegetation growth period, but the major fat deposition occurred in late summer and autumn when most crops were at their peak. The kidney fat index appeared to follow the same general seasonal pattern in west and south Texas, but samples through the year in west Texas were too small for meaningful comparison. It i s evident from Fig. 7 that the period of good conditions in south Texas beginning in the spring of 1965 resulted in greater fat depos-ition (up to a K.F. index of 3/4 in two instances and 1.0 in one instance) that kept the K.F. index high through the summer and into winter. However, during the drought that started in mid—1966 the animals did not put on much fat; consequently, the K.F. index was much lower during the summer and f a l l of 1966 than during 1965. There was l i t t l e difference in the K.F. index in late winter of both years. Peccaries collected on the Black Gap area in 1965 near the end of a minor drought had a slightly lower K.F. index than did those collected in 1966 after a year of good r a i n f a l l . This was more evident in the females, who went from a mean K.F. index of .18 in 1965 to .28 in 1966, than i t was in the males, who went from .23 in 1965 to .26 in 1966. (Fractions were transposed to decimal figures to f a c i l i t a t e comparison. It should not be inferred that accuracy i s precise to two decimal points.) Animal condition was better during the period of good range conditions in late 1965 in south Texas and lower when range conditions were poor in late 1966, whereas condition was lower in 1965, and higher in 1966, in west Texas. Although sample sizes are smaller during late f a l l in south Texas than in west Texas, the combined September to December sample is large enough for cojftparison. K.F. indices from south Texas peccaries ranged from 34. n = 6 5 12 3 3 1 11 7 11 6 3 8 5 7 7 1 3 4 3 F M A M J J A S O N Figure'7. Seasonal changes in kidney fat indices in south Texas peccaries during moist (•) and drought (O) conditions, 1965-67. Values given are mean, 95% confidence interval and the range. 35. 1/4 to 3/4 with a mean of .49 (n = 17), whereas in west Texas the range was 0 to 1/2 with a mean of .20 (n = 59). In late 1966, the K.F. index of south Texas peccaries ranged from • to 1/2 with a mean of .21 (n = 6), whereas the west Texas peccaries were in slightly better condition indicated by a mean K.F. index of .26, with a range of • to 3/4 (n = 52). Thus under relatively good r a i n f a l l and range conditions in west Texas, peccaries there reached a condition slightly better than condition of south Texas animals under drought conditions (Table 2). The south Texas peccaries under good range conditions almost equalled the condition of pen—reared peccaries (Table 2). Table 2. Comparison of F a l l kidney fat indices of adult captive, south Texas and west Texas peccaries under different moisture, con-ditions. Sample size i s shown in brackets. S o u t h T e x a s W e s t T e x a s Captive Moist Drought Moist Dry Condition K.F. index .58 (6) .49 (17) .21 (6) .26 (52) .20 (59) 4.3. Growth Weights of three/, known-age foetuses obtained near mid—pregnancy (105 days) from a captive sow averaged 237 gm (192-279 gm) . Weights of 15 neonatal peccaries ranged between 570 and 1090 grams, with a mean of 767 gm (1.6 lbs) (Table 3). Eight neonatants that died within a day of birth averaged 525 gms (SD = 132), 33°/o lighter than their surviving siblings. A l l of the neonatants that died had aerated lungs, so presumably were born alive, but direct-;'cause of death could bot be determined. Usually the dead animal was one of twins or triplets and the survivors in the l i t t e r s were of average or greater than average weight. 3 6 . Table 3 . Weights of neonatal peccaries (pen-raised and wild). No. Sex Age Wt (gm) Weight (lb-oz) UBC 3 9 1 F 4 day 7 6 6 1 - 1 1 " 3 9 2 IM 4 " 7 9 5 1 - 1 2 " 3 9 3 F birth 6 8 1 1 - 8 " 3 9 4 F I I 6 8 1 1 - 8 " 3 9 6 M I I 7 3 8 1 - 1 0 " 3 9 5 F I I 7 6 6 1 - 1 1 " 3 9 7 F 1 day 9 0 8 2 - 0 " 4 0 0 M 1 " 5 6 8 1 - 4 " 4 0 1 F 1 " 7 3 8 1 — 1 0 " 4 1 3 M 3 " 6 8 1 1 - 8 " 3 9 8 • M birth 7 3 8 1 - 1 0 " 3 9 9 M 6 8 1 1 - 8 P - 2 5 M 1 day 9 5 3 2 - 1 Pecos M 2 " 1 0 9 0 2 - 4 P - 1 7 5 M birth 7 2 2 1 - 7 Only A l l l i v e pen—born neonatants n 1 2 1 5 X 7 2 8 7 6 7 SD 8 2 1 2 9 SE 2 4 3 3 9 5 ° / o Conf. + 5 2 + 7 1 Captive animals weaned^2, to 3 months, weighed 7 to 1 0 lbs (Fig. 8 ) , and at one year, the hind leg and total length had almost reached adult size. In wild south Texas animals body weight was s t i l l considerably less than for mature adults at one year (Rig. 8 , Table 3 ) . Pen—reared animals fed ad libitum on a good diet reached adult body weight of 5 0 lbs at just under 1 1 / 2 years and peak adult weights fluctuated around 6 0 lbs (Fig. 8 ) . Wild peccaries did not reach this weight until they were well into their third year, and peak adult weights fluctuated around 5 0 lbs. Peak weight was reached around 5 years and there was a slight decline in weight of the collected animals older than 6 years (Fig. 9 and 1 0 ) . The data shown in Figures 8 , 9 , and 1 0 indicate that the south Texas pec-caries do not grow at the potential rate shown by the pen—raised peccaries. Data from young west Texas peccaries were too few for meaningful comparison. Weights of 1 and 2 . year old west Texas animals were heavier than south Texas animals in Figures 9 and 1 0 because the average age of the f a l l collected west Texas animals was older than that of the south Texas animals who were collected throughout the year. Live weight of south Texas peccaries 3 years and older collected during the study averaged 5 1 . 2 lbs for males and 5 2 . 0 lbs for females CJ O Figure 8. Relationship of l i v e weights to age of pen—reared (•) and co l l e c t e d (o) south Texas peccaries. Values given are the mean and confidence i n t e r v a l . LIVE W T (pounds) AGE ( months) 39. F i g u r e 9. C a r c a s s w e i g h t s o f s o u t h ( 0 ) and west ( • ) Texas male p e c c a r i e s . . V a l u e s g i v e n a r e mean, 95°/> c o n f i d e n c e i n t e r v a l , and t h e r a n g e . F i g u r e 10. C a r c a s s w e i g h t s o f s o u t h ( 0 ) and west ( • ) Texas f e m a l e p e c c a r i e s . V a l u e s g i v e n as f o r F i g u r e 9. 50. Carcass Wt (lbs) 40. 30. 20 if}--N = l 14 11 22 4 3 6 » 0 2 1 40, 10 2 37 27 AGE IYRS) 1 4 5 6 7 MALES >7 >2 C a r c a s s Wt. (lbs) 40 30. 20. N = 6 12 8 14 7 4 4 6 11 2 6 3 2 0 §11 18 4 46 23 AGE IYRS) 1 2 3 4 5 6 7 FEMALES >7 >2 41.. (Appendix D). The difference in l i v e weight between sexes was not significant. Carcass weights expressed as a percentage of l i v e weight are 68°/o (56-77%) for males, and 62.3% (55-78%) for females. In carcass weights of animals 3 years and older, males averaged 34.9 lbs. and females 32.0 lbs. (Appendix D) and males were significantly heavier (P = .01) than females because of significantly heavier heads and forequarters on older males (P = .01) (unpublished data). Appendix D also l i s t s age specific total length, hind leg length, arid girth of south Texas peccaries. West Texas peccaries were slightly lighter, but longer legged than south Texas peccaries (Table 4). Live weights from west Texas peccaries were obtained on only nine animals 3 years or older, too few to be meaningful, Carcass weights averaged 33.4 pounds for 27 males and 30.9 pounds for 25 females 3 years and over. The difference between sexes i s significant (P < .01). The west Texas males averaged 1.5 lbs lighter than south Texas males (P < .1) (Fig. 9). West Texas females were only 1.1 lbs lighter than those from south Texas (P < .2) (Fig. 10). It should be noted that most of the west Texas animals were collected in early winter, a time of peak weight in south Texas peccaries, and presumably also a time of peak weight in west Texas peccaries. Table 4. Size comparison of adult peccaries from south and west Texas. Carcass Weight (lb) Age Male n Female n Difference P South Texas 3-15 yr. 34.9+1.4 (32) 32.0+1 ..'2 (46) 2.9 lbs .01 West Texas 3-9yr. 33.4+1.9 (27) 30.9+1.7 (25) 2.5 lbs .01 .difference 1.5 lbs n.s. 1.1 lbs n.s. Total Length (inches) South Texas 3-15 yr 38.2+.5 (38) 38.9+.4 (48) 0.7 in .05 West Texas 3-9 yr 37.9+.8 (27) 38.1+.9 (26) 0.2 difference .3 inches n.s. .8 inches n.s. ns Hind Foot Length (inches) South Texas 3-15 yr 7.2+.1 (38) 7.2+.1 (48) 0 West Texas 3-9 yr 7.5+.1 (15) 7.5+.1 (16) 0 difference .3 inches P .01 .3 inches P .01 There was l i t t l e difference in the total length measurement of the peccaries from the two regions (Table 4). Males were slightly shorter than females in both areas, but the difference was significant only in south Texas. Hind leg length was the same for both sexes, and was sig -42. n i f i c a n t l y longer in west Texas animals than i n south Texas peccaries (P < .01) (Table 4). There was some change i n carcass weights of animals collected under different r a i n f a l l conditions. The average carcass weights of peccaries collected during the period of good r a i n f a l l i n 1965-66 were 1.7 lbs (5c/o) f o r males, and 3.6 lbs (12°/O) for femal es, heavier than those collected during the 1964-65, and 1966-67 droughts (P = .2 for males, and P = .01 f o r females) (Table 5). Although precipitation and vegetation growth i n west Texas were generally better i n 1966, and animals were i n s l i g h t l y better condition, the data on carcass weights from the two years for both sexes are equivocal. Females were 0.8 lbs l i g h t e r i n 1966 (P = .3), and males were 2.9 lbs heavier i n 1966 (P < .1) than they were i n 1965 (Table 5). Table 5. Comparison:.of carcass weights of adult peccaries i n low and high r a i n f a l l periods. Conditions \ Male- (2+ yr) Female (2+ yr) West Texas 1965, low pptn 32.6+1.8 Mil 31.3+2.1 ho] 1966, High pptn 35.5+3.2 (13) 30.5+3.8 (10) difference 2.9 "[1966)- n.s. (P<.1) 0.8"[l965) n.s. South Texas pptn above avg. pptn below avg. difference 35.6+2.2 (18) 33.8+2.0 (22) 1.7Xgoodyr) n.s. (P <.2) 33.6+1.4 (26) 30.1+1.7 (17) 3.6 Tgood yr) (P < .01) Weight changes of wild peccaries appear to have a basic seasonal pattern which i s not apparent i n pen-reared animals. Fig 11 (females) and 12 ( males) show that weights of trapped and collected peccaries older than two years were depressed i n early summer, dropped further during the summer dry period, and increased again through the wet winter of 1965-66. Males continued to gain weight through to the summer dry period of 1966. Females l o s t weight e a r l i e r i n 1966, perhaps due to presence of suckling young. Weights remained low through the f a l l of 1966 and u n t i l l a t e spring, 1967, when they rose at the time when a small mast crop and some new vegetation were produced. Figure T'il Live and carcass weights of trapped and collected female peccaries older than two years from south Texas. Values given are mean, standard error at the t n „ l e v e l and the r a i ge. '• 44. 60 55 50 g 45 -p *i—I ^ CD 35 30 25 20 Sample size ( l i v e ) 2 21 5 11 5 - 2 5 Sample size (hog-dressed) £ > 2 1 3 6 1 2 5 8 3 1 [mar-apr 'may ^ un 1 july-aug1 sept- ' nov - I ; a n . ' m-a * m- j ' \ - a ' s-o W-dec lion-feb'm - a ' m - i 'iuly-auq' I 1965 d e c 1 , e b 1966 1 1967 196 .MOIST' DROlIIGWi Figure 12. Live and carcass weights of trapped and collected male peccaries older than two years from south Texas. Values given are mean, standard error at the t l e v e l , and the range. 45. 4.4 The populations 4.4.1. Density Densities of the four peccary populations that were studied de-creased on an east-west gradient as did precipitation (Fig. 1). A total count of peccaries was possible on the Welder Refuge. A maximum of 120 peccaries was reported from a combined aerial and terrestrial survey in the spring of 1966. This represents a density of 10 peccaries/sq mile. Although total counts were not obtained in 1965 and 1967, i t was estimated that there were almost 100 peccaries present in the spring of 1965, and fewer than 80 in the spring of 1967. These represent densities of 8.3 and 6.7 peccaries/sq mile. On the King Ranch, density was estimated on the basis of strip counts. These were continued for 18 months and yielded estimates that varied from 10.7 to 49.2 peccaries/sq mile, and the mean density was 21.8 peccaries/sq mile (Table 6). Table 6. Peccary density estimates in Mesquite Pasture of the King Ranch from strip census. Avg No Trans Density No. of Peccaries h Area (per sq) Counts per Count S.D.9 CV. (Acres) (mile) Sept, 1964 Pita M i l l 15 7.3 7.6 104 436 10.7 Feb-Apr, 1965 Pita M i l l 5 33. 26.2 79 436 49.2 Apr-July,1965 Escondido 3 19.7 17.6 89 580 21 .5 M i l l July-Dec,1965 Escondido 14 4.4 4.0 91 167 16.8 M i l l Feb-May, 1966 Escondido 5 10.8 8.7 81 335 20.6 Mi l l Mean density 21 .8 a - Standard Deviation g ^ b - Coefficient of Variatiation = ' x Avg Peccary density in the arid west Texas areas was considerably lower than in south Texas. An estimate of the density on the Watson Ranch, based on sightings by myself and ranchhands, was slightly more than 3.1 peccaries/sq mile. This is probably a conservative estimate. The peccary population on the Black Gap Management Area determined from sightings, hunter reports, and the annual k i l l , has been estimated at about 6.4 peccaries/sq mile (L.S. 46, Brownlee, Pers. Comm.). However, t h i s estimate i s probably l i b e r a l . Although the density of peccaries i n each of the areas could not be determined precisely the differences i n population density i n the two regions are of such magnitude as to be unmistakable (Table 7). Table 7. Peccary density estimates on four study areas i n south and west Texas. Density (Peccaries/sq mile) Area . 1963 1965 1966 1967 Mean South Texas King Ranch 17.8 22.9 20.6 20.4 Welder Refuge 9.8 9.8 West Texas Watson Ranch 3.2 3.2 Black Gap M.A. 6.4 6.4 4.4.2. Home Range and Movements As further evidence of differences in population density, the sizes of the home ranges were determined. Peccaries are non-migratory and home ranges are quite small. My observations of ear-tagged and radio transmitter-tagged peccaries indicate a home range of less than 3/4 sq mile (480 acres) f o r animals on the King Rianch and the Welder Refuge. Two herds on the King Ranch had minimum home ranges of 390 acres and 300 acres respec-t i v e l y . The Venado Bend herd on the Welder Refuge had a home range of about 440 acres. On the Watson Ranch i n the more arid part of Texas, three herds were observed to move fr e e l y within areas up to 4 sq miles. These areas included adjacent mesas and t h e i r associated arroyos. There were some exceptions to the small home ranges in south Texas, but these might better be termed wanderings. One adult male peccary tagged at trap 3 in Mesquite Pasture was k i l l e d about two mile NE on the Pita-Guttierez fenceline. (G. Schacherl, Pers. Comm.). Another male trapped on the east fence of P i t a Pasture was released at Trap 3, two miles away, and observed 6 months l a t e r back at the point of capture. 4 7 . 4 . 4 . 3 . Population Structure Sex Ratio Sex ratios of peccaries change considerably with age in both south and west Texas populations (Table 8 ) . L i t t e r s obtained i n utero from 3 4 sows in south Texas yielded 6 1 foetuses D f which 5 5 could be readily sexed. The sex r a t i o favoured females ( 4 2 ° / o males to 58° /> females) . When the single west Texas l i t t e r , and the 3 2 foetuses born i n c a p t i v i t y were added the r a t i o was nearer to equal, but s t i l l favoured females, 4 7 ° / o males to 5 3 % females. Table 8 . Age s p e c i f i c sex ra t i o s of pen-born, south Texas and west Texas' peccaries. West S o u t h T e x a s Texas Captives Total Collections Trapping Total Collections foetuses 4 2 : 5 8 ( 5 5 ) 4 2 : 5 8 ( 5 5 ) 5 0 : 5 0 ( 2 ) 5 6 : 4 4 ( 3 2 ) 4 7 : 5 3 ( 8 9 ) 3 mo 6 4 : 3 6 ( 1 1 ) 7 0 : 3 0 ( 2 0 ) 6 8 : 3 2 ( 3 1 ) 1 0 0 : 0 ( 2 ) 6 2 : 3 8 ( 2 1 ) 6 7 : 3 3 ( 5 4 ) 4 - 1 2 mo 6 0 : 4 0 ( 2 0 ) 5 4 : 4 6 ( 4 0 ) 5 6 : 4 4 ( 6 0 ) 5 5 : 4 5 ( 2 2 ) 5 5 : 4 5 ( 8 1 ) 1 3 - 3 6 mo 5 2 : 4 8 ( 2 7 ) 5 2 : 4 8 ( 2 7 ) 5 7 : 4 3 ( 6 0 ) 5 5 : 4 5 ( 8 7 ) 3 - 7 yr 4 8 : 5 2 ( 6 0 ) 4 8 : 5 2 ( 6 0 ) 4 6 : 5 4 ( 2 8 ) 4 8 : 5 2 ( 8 8 ) 7 + yrs 4 2 : 6 8 ( 3 1 ] 3 2 : 6 8 ( 3 1 ] 5 0 : 5 0 3 6 : 6 4 ( 3 9 ) 1 + yrs 4 4 : 5 6 ( 1 2 0 ) 4 1 : 5 9 ( 1 1 2 J 4 3 : 5 7 ( 2 3 2 ) 5 3 : 4 7 96 4 6 : 5 4 ( 3 2 8 ) Note: Sex r a t i o i s % Males:% Females (Sample s i z e ) . The sex ra t i o s made an abrupt, although temporary, reversal at b i r t h . Sex r a t i o s of young less than three months old strongly favoured males, , 67% males to 3 3 % females (Table 8 ) . Between 3 and 7 years the sex ratios became equal, and in animals older than 7 years, the sex r a t i o strongly favoured females ( 3 2 % males to 6 8 % females) in south Texas. The average sex r a t i o for animals older than 1 2 months in south Texas determined from 1 1 2 l i v e -trapped and 1 2 0 collected animals favoured females ( 4 3 % males to 5 7 % females). In west Texas the average sex r a t i o for a l l animals older than 1 2 months was 5 3 % males to 4 7 % females, but for the 3—to—7—year class the r a t i o favoured females ( 4 6 % males to 5 4 % females). When the collected foetuses, collected young, and trapped young from south Texas were divided into three categories (minor drought, above average p r e c i p i t a t i o n , and drought conditions) there was no consistent trend between the sex ra t i o s for the three periods (Table 9 ) . 4 8 . Table 9 . Age s p e c i f i c sex ratios of young south Texas peccaries ^  conceived or born under different climatic conditions. Minor ^ Moist Drought Drought Total foetuses 4 4 : 5 6 ( 4 1 J 5 0 : 5 0 ( 6 ) 2 5 : 7 5 ( 8 } 4 2 : 5 8 ( 5 5 ) 3 mo 6 9 : 3 1 ( 1 6 ) 7 1 : 2 9 ( 7 ) 6 0 : 4 0 ( 5 ) 6 8 : 3 2 ( 2 8 ) 4 - 1 2 mo 6 0 : 4 0 ( 3 0 ) 5 6 : 4 4 ( 1 6 ) 6 4 : 3 6 ( 1 4 ) 5 6 : 4 4 ( 6 0 ) Total 5 4 : 4 6 ( 8 7 ) 5 9 : 4 1 ( 2 9 ) 5 2 : 4 8 ( 2 7 ) 5 5 : 4 5 ( 1 4 3 ) Note: a - above average precipitation and range conditions, June, 1 9 6 5 to June, 1 9 6 6 . b - terminal portion of minor drought, to May,. 1 9 6 5 . c - drought conditions July, 1 9 6 6 to Aug. 1 9 6 7 . d - ra t i o s are °/o males to °/o females (sample size) . Age Structure The age structure of the south Texas peccary population estimated from l i v e trapped and collected samples, i s shown i n F i g . 1 3 . Since the collections were for the purpose of obtaining adult specimens, the younger age classes were under—represented. Although the bias may carry through to the 3 - o r 4-year classes (the time when maximum size i s approached) i t i s only serious f o r animals under 2 years old. The trapping results are pre-sumably bias-free and since the ages of these animals were determined as juveniles, (under 1 2 months) young adults ( 1 to 2 years) and older adults, I have incorporated these juveniles and young adults into the ,age structure curve. Of 1 6 7 peccaries trapped, 5 9 were less than 1 year old. The animals less than 1 year old that were collected were replaced in the population age curve with the correct proportion determined from the trapped sample. The sex r a t i o s of the two samples were almost i d e n t i c a l , so there was no problem in aportioning the sample between sexes. The same was done for the 1. to 2 year olds. In th i s group there were several animals i n i t i a l l y classed as young adults that were l a t e r estimated at 2 6 months old, so the age curve may over—represent t h i s age class s l i g h t l y . The ages determined by dental annulations showed that almost 1 5 c / o of the south Texas sample i s over 7 years old. The oldest animal obtained was a 1 5-year old female. Figure 1 3 also shows the age structure of the west Texas col l e c t i o n s , including both the Black Gap and Watson Ranch samples as there was l i t t l e difference i n the age structure of the two samples. I t was not possible to correct f o r the under-representation of young animals i n west Texas as was 4 9 . 30% 20% 10% WEST TEXAS 0 males (n=64) • females (n=55) •1 In In m l ! <1 1 2 3 4 5 6 7 8. AGE IN YgkRS 10 11 12 13 14 15 4 0 $ 30% • SOUTH TEXAS OU males (n=109) • females (n=109) 10% J Z 1 HI r rrr-i r m r—1 <1 1 2 3 4 5 ' 6 7 8 9 AGE IN YEARS 10 11 12 13 14 15 Figure 1"3.Age d i s t r i b u t i o n of peccaries collected and trapped i n south Texas and collected i n west Texas. 50. done for the south Texas population. Hence, the two curves are not comparable in the youngest age classes. It i s apparent from comparison of the two populations that the west Texas population i s much younger than the south Texas population, and that the 2 to 3 year olds make up the largest part of the adult population. No animals over an estimated 9 years old were obtained in west Texas. With the ages of the animals estimated to the year, i t was possible to construct l i f e tables for the south and west Texas populations (Tables 10 and 11). In south Texas, the data obtained from trapped animals under 2 years at i n i t i a l trapping and the collected animals over 2 years are assumed to represent the proportions of each age class li v i n g at the start of that age interval ( l ). The shrinkage between each group then gives a measure of the mortality (d ) during that age interval. The sample was collected over a 2 1/2 year period and partly overcomes the irregular addition of young to the population each year as Deevey (1947:298; 1964) suggests. The high survival in 1966 and low survival in 1967 tend to average out, and render mean mortality figures useful. Anomalies are s t i l l present in the table, presumably because of sample size, sample selection, or unequal birth and survival rates during some periods. Examination of the trends in the l i f e expectancy column of Table 10 emphasize the higher mortality in the early and later years and the lower mortality rate between the ages of 2 to 7 years. The mean annual mortality rate i s 21.5% for the population. The l i f e table for the Black Gap population (Table 11) was deter-mined from 2 years of hunter collections and because of the magnitude of the anomalies resulting from small sample size, possible unequal survival rates between periods, and non-representative collection of smaller animals less than 2 year old, the trends are not as apparent. Life expectancy does however, tend to be shorter. The annual mortality rate averages 27.5°/o. The slopes of the regressions of population size on age for the two populations (Table 10 and l l ) are not significantly different, chiefly because of limited data for the West Texas population. Table 10. L i f e table for south Texas peccaries based on 218 animals collected and trapped on the King Ranch (see text f o r d e t a i l s ) . Age - 1 x dx e x (years) no. at no. d,:y ing mortality l i f e s t a r t of during rate expectancy i n t e r v a l i n t e r v a l 0 64 20 .31 2.9 1 44 25 .57 3.0 2 19 7 .37 5.2 3 12 1 .08 7.0 4 11 + 8 + .73 6.6 * 5 19 5 .26 3.0 6 14 10 .71 2.9 7 4 + 7 +1 .75 8.2 * 8 11 4 .36 2.3 9 7 3 .43 2.4 10 4 3 .75 ' 2.7 11 1 + 2 +2.00 8.5 * 12 3 1 .33 2.2 13 2 0 .00 2.0 14 2 1 .50 1 .0 15 r1 1 ' 1 .00 0.5 * anomalies due to sample size, sample selection , or unequal b i r t h or survival rates. Y = 3.76 - .24X .., R = .925 Y = population size , x = age Table 11 . L i f e table f o r 102 Black Gap peccaries over 12 months old collected by hunters. Age 1x 3x e x (years) no. at no. d y.dng mortality l i f e s t a r t of during rate expectancy i n t e r v a l i n t e r v a l 1 26 + 8 + .38 3.4 * 2 34 31 . .91 1 .7 3 3 +10 +3.33 13.7 * 4 13 + 3 + .39 2.5 * 5 16 13 .81 2.9 6 3 2 .66 2.8 7 1 0 .00 6.5 8 1 + 4 +4.00 5.5 * 9 5 5 1 .00 0.5 Y = 3.35 - .32X\ , R = .715 notes as for table .10. 52. 4.5. Male reproduction 4.5.1. Morphology of the Male Reproductive Tract. The basic anatomy of the male reproductive tract i s s i m i l a r to that of the domestic boar described by Nalbandov (1958) and Mann (1969). The following description i s of the trac t of a 3 1/2 year old male (Pc 183), shown i n Plate 2. The testes are 1 3/4 inches long by 1 1/4 inches diameter. The vas deferens i s 9 1/2 inches long, with no terminal ampulla. The seminal vesicles are well developed triangular structures 2 1/2 inches by 1 1/2 inches by 1 inch deep. Jhe prostate gland forms a 3/4 inch diameter sphere around the juncture of the vas deferens, seminal vesi c l e and urethra. The well developed bulbourethral gland i s an elongated tube 3 1/4 inches long with a diameter of 1 1/8 inch. The penis i s about 9 1/2 inches from i t s pubic attachment and has the t y p i c a l "cork-screw" shape and reverse flexure of the domestic pig. 4.5.2. Growth and Seasonal Change i n Testis Size. •ne hundred and eighteen pairs of testes were examined from pec-caries from south arid west Texas and from captive animals. The testes were scro t a l from at least one month pr i o r to bi r t h and remained that way through-out tha animal's l i f e t i m e . At b i r t h the testes had a size index (T.I. = t e s t i s weight -\- hind leg length) of 0.03. Growth was r e l a t i v e l y slow for 7 to 8 months. There was then a sharp gain i n the t e s t i s index of south Texas peccaries from 0.4 to 1.0 between 9 and 10 months. (Fig.14, Table 12). The testes approached adult size by 18 months and gradually increased to a TI of 3.06 at 5 years, and the plateau was maintained through 7 years (Table 13). Over t h i s age the index declined.slightly to a mean of 2.7 for a l l animals older than 7 years. Table 12. Growth i n testes for young south Texas peccaries. wt T . I . Index 95°/o Age n (gm) X Range SD Sx Conf. Lim 1 day 1 0.1 .03 .2 yrs 1 D.6 .12 .3 6 1 .9 .35 .16-.55 13 .05 .13 .5 1 2.4 .38 .6 4 2.9 .44 . .3-.54 .11 .06 .18 .7 1 6.7 .92 .8 2 6.8 1 .04 .98-1.1 1 .5 2 17,; 4 2.4 2.1 -2.7 1 .8 1 9.1 1 .2 2.2 5 17.3 2.46 1.8 -3.0 .53 .24 .65 53. Plate 2. The male reproductive t r a c t . a. The t r a c t removed. Note the extensive dark i n t e r s t i t i a l tissue in the t e s t i s , the large tubular bulbourethral gland, the straight vas deferens crossing the surface of the seminal vesicles (lower center), and the s p i r a l flexure of the penis (upper r i g h t ) . b. Cross-section of the t e s t i s one-third of the distance from the caput epididymis. Note the tubule clumps and the secretion sinuses. (Histological section). c. Cross-section of the t e s t i s i n the central area. Note the tubules extending towards the central rete t e s t i s . (Fresh section). d. Cross-section of the t e s t i s one-third of the distance from the cauda epididymis. Tubules converge i n central rete t e s t i s and connect with vasa efferentia below lower center of picture. The white streaks are secretion sinuses. (Histolog-i c a l section). 54. 55. Figure 14. Change i n t e s t i s index (Tl) with age of individual south and west Texas peccaries. Figure 15. Seasonal change i n t e s t i s index of adult south Texas peccaries. Mean, range and 95% confidence i n t e r v a l are given. 56. Q 2 1 . • • • • So. Texas o West Texas AGE 1 yr 3 4 5 6 7 S 9^14 3 - 5 3.0 Q 2 ,2.5 2.0 ^3 range^^ r-i mean-J 5 F 6 2 12 8 J 3 J 5 A 3 3 1 S O N D 57. Table 13. Age specific testis size for adult south Texas peccaries. wt T.I. Index 95°/, Age n xfgm) X Range SD Sx Conf. Lim 2 yrs 11 3.4 2.38 1.8-3.0 .41 .12 .28 3 5 19.2 2.68 1.9-3.5 .63 .28 .78 4 5 16.5 2.4 2.2-2.7 .20 .09 .25 5 8 22.2 3.06 2.3-3.6 .41 .15 .35 6 8 20.4 2.83 2.4-3.4 .36 .02 .04 7 2 22.7 3.15 2.8-3.5 .49 .35 4.2 8-14 yrs 9 19.6 2.7 .39 .02 .04 X 48 16.3 2.69 1.8-3.6 .22 .001 .002 At birth, the testes of west Texas peccaries were about the same size as those of south Texas animals, but growth appeared to be slower and mature size was not reached until about 2 years (Fig. 14", Table 14). Testis size also peaked at about 5 years, but at an index of'2.23, which was considerably lower than the south Texas peccaries (Table 15). Since the index is derived using the leg length, which was significantly longer in west Texas peccaries, the index appears smaller for west Texas animals. However, the mean weight of testes from south Texas 2-year old peccaries was 3.4 gm heavier (P < .01) than weights of those from west Texas 2-year old peccaries. Table 14. Growth in testes for young west Texas peccaries Age n wt x (gm V1' )x Index Range SD Sx Sxt.05 .1 1 0.3 .067 .3 1 0.5 .085 .4 4 1 .4 .185 .15-.29 .07 .035 .110 .7 1 4.0 .59 .8 1 5.2 .74 1 .0 3 5.2 .71 .4-.93 1 .3 1 6.0 .8 1 .6 2 10.5 1 .4 1 .2-1 .6 1 .8 1 12.0 1 .5 58. Table 15. Age specific testis size for adult west Texas peccaries. wt T.I. Index Age n K (gn i)x Range SD Sx Sxt.05 2 yrs 17 13.7 1 .86 1.3-2.4 .34 .08 .17 3 yrs 2 14.6 2.04 1.8-2.3 .37 .26 3.12 4 yrs 3 13.0 1 .67 1 .5-1.9 .21 .12 .52 • 5 yrs 3 16.7 2.23 1.8-2.6 .40 .23 1 .00 7-9 yrs 5 15.3 2.06 1.1-2.8 .77 .34 .96 X 30 14.3 1 .88. 1.1-2.8 .45 .08 0.16 There appeared to be a seasonal change in testis size in mature animals. The TI was high from March through-July, and low from August through to February (Fig. 15). The testes were available from only one adult male in the period November through January; however, the TI of 17 adult males collected in August, September, October and February averaged 2.42 whereas the March-July sample had an average index of 2.84 (difference 0.34, P.< .05) . The size difference between testes from west and south Texas peccaries i s probably related to condition. Pen—reared peccaries had testis--weights and indices much higher than the south Texas peccaries who, in turn, had heavier testes than the west Texas peccaries (cf. Tables 12— 16). This showed the same pattern as the condition index. Comparison of the TI of males collected in south Texas between June, 1965, to June, 1966 (moist conditions), and July, 1966, to August, 1967 (draught conditions) showed l i t t l e difference Table 17. However, when the unequal distribution of samples through the season was controlled by taking data only from prime animals collected during the spring and early summer of both periods, the TI was slightly higher from the animals collected during the period of good conditions (Table 17). One exception to these generalities was a 2.1 year old west Texas male, BG 537, who had a TI of 4.3, and testis weight of 32 gm. This animal was not included in the s t a t i s t i c a l treat-ments because of the abnormal size of the testes, although they appeared normal otherwise. 59. Table 16. Testis weights and indices of pen-reared peccaries. Age n wt xfgm) T l X Range 1 da. 1 0.1 .03 .3 yr. 3 2.1 .40 .32-.55 .4 yr. 1 3.8 .65 1.5 yr. 2 18.7 2.6 2.1-3.1 1.8 yr. 1 18.2 3.2 3.0 yr. 3 24.9 3.5 3.0-4.0 Table 17. Testis size of south Texas adult peccaries compared by drought conditions. wt Tl ^.Conditions n x (gm)x Range SD Sx 95c/a Conf. Periods 3 18.2 2.8 2.6-3.1 .25 .15 .6 mild drought Mar-May 1965 2 yrs. 27 19.1 2.6 1.9-3.6 .45 .09 .18 moist & June/65—June/66 older 19 18.72 2.6 1.8-3.4 .31 .10 .39 drought July/66-Aug/67 3 to r. 5 20.0 3.3 2.8-3.6 .34 .15 0.4 moist years old June/65—Aug/65 8 21 .1 3.1 2.7-3.4 .25 .09 0.2 Adult west l ' Texas peccaries collected during November and December on the Black Gap area showed a s l i g h t (but not si g n i f i c a n t ) increase i n t e s t i c u l a r weights from November to December. This c o l l e c t i n g period was only three weeks long and therefore a s i g n i f i c a n t difference would be unlikely. When' 1965 data (low r a i n f a l l ) were compared with 1966 data (high r a i n f a l l ) , however, the 1966 t e s t i s indices were s i g n i f i c a n t l y higher (P<.05) than 1965 t e s t i s indices (Table 18). 60. Table 18. Testis size of west Texas adult peccaries (2 years and older) compared by month and year. wt TI P e r i o d n x (gm ) x Range SD Sx 95% Conf 1965 & Nov. 13 14.1 1 .86 1.1-2.8 .50 .14 .31 1966 Dec. 13 14.7 2.0 1 .3-2.6 .37 .10 .23 Nov. & Dec. 26 14.4 1 .93 1.1-2.8 .45 .09 .18 Jan. - Dec. 33 13.7 1 .88 1.1-2.8 .45 .08 .16 Dry 1965 Nov. & Dec. 9 13.2 1 .77 1.1-2.4 .46 .15 .36 Moist1966 Nov. & Dec. 17 15.03 2.02 1.4-2.8 .42 .10 .22 4.5.3. Histological Examination of Testes Testes are not homogeneous through their length; the tubules drain into the central rete testis, and hence through the vasa efferentia to the caput epididymis (Plate 2 b, c, and d). These differences were of l i t t l e consequence in this study because a l l of the testis sections for histological comparison were taken from the mid-section of the testis (Plate 2c), and the error introduced by location was minimal. Tubule lumina were relatively empty near the periphery of the testis, but towards the center, they became f i l l e d with sluffed cells and detritus. This same detritus was also present in the rete, vasa efferentia and epididymis, and was present in a l l adult peccaries. At birth, the testicular tubules were relatively small, 54 JJ diameter, and made up only 1/3 of the mass of the testis (Fig. 16, Appendix E). At this time there were only spermatogonia and Sertoli cells present in the tubule. The spermatogonia began to form spermatocytes between three to four months. At this time the tubules were s t i l l only 1/3 of the test-icular mass, the TI = .34, and the tubule diameter was about 60 p. There was l i t t l e change in relative size and proportion in the testis until about 8 months, when concurrent with the rapid growth of the testes, spermatocytes became common and occasional spermatids appeared in the tubules. The tubules reached 115 JJ diameter, although they were s t i l l l i t t l e more than a third of the volume of the testis. Between 9 to 10 months, when the TI = 1.0, a few spermatozoa appeared' in the tubules. At this time the tub-ule diameter averaged slightly greater than 125 and the tubules had increased to 40% of the testis volume. Spermatozoa did not become common until the animal approached 11 months (average 35.6 sperm/tubule cross-section) when the tubule diameters exceeded 150 y and were 50% of the • cn _^  Figure 16. Change in testis index, sperm counts (per tubule cross-section"), proportion of tubules (%), and tubule diameter (u) with age of 41 south Texas peccaries. 63. t e s t i s volume. I t was around t h i s age that pen-reared males successfully f e r t i l i z e d sows 10.7 months i n Arizona (Sowls, 1966) and 11.6 and 11.8 months at U.B.C. and the Welder Refuge (this study). I did not f i n d a tubule cross-section with over 100 spermatozoa u n t i l the male was over 2 years old when"diameter was 173 JJ and tubules comprised 72% of the t e s t i s . Tubule diameter appeared to reach i t s maximum size, over 200 JJ, by 2 1/2 years (Fig. 16), and i t appeared to be main-tained to at least 9 years. A 12- and a 14-year old male both showed s l i g h t l y smaller average tubule s i z e , 181 and 182 JJ, but spermatozoa s t i l l averaged 155 and 76 per tubule cross-section. The proportion of the adult t e s t i s comprising tubules varied between 60% and 8D°/o; but i n the 12-year old male i t was only 54%, and i n the 14-year old, 81c/o. I t should be noted that the 12-year old male (P-5) had a poorly developed (12.9 gm) right t e s t i s . The tubules were quite large (154 JJ) i n the small right t e s t i s and an average of 60.6 spermatozoa per tubule, cross—section were present, but the tubules were only 13% of the t e s t i s . The l e f t t e s t i s appeared normal except that some of the tubules had thick connective tissue walls. 4.5.4. Seasonal Changes in H i s t o l o g i c a l Structure of Testes The small sample size and the fact that the testes analysed were chosen because they were average or below average size preclude firm con-clusions of seasonal change i n t e s t i s structure. The proportion of the t e s t i s comprised of tubules tended to be higher i n the l a t e spring and summer and lower i n the f a l l (Fig. 17), l i k e the t e s t i s index. Conversely, the i n t e r s t i t i a l tissue, including the secretory c e l l s , comprised a higher proportion of the t e s t i s volume i n the f a l l . Multiplying the percent i n t e r s t i t i a l tissue by the t e s t i s weight to adjust f o r the change i n t e s t i s weight, indicated that more secretory i n t e r s t i t i a l tissue was present i n the f a l l and winter than i n the summer. The diameter of the tubules, and the number of sperm per tubule cross-section, appeared to be inversely related to the proportion of the t e s t i s comprised of tubules (Fig. 17). Thus i t appears that as the pro-portion of the i n t e r s t i t i a l tissue increased, the tubules became larger and the number of sperm per tubule cross-section increased. Since there was a decrease i n the size of the t e s t i s i n the f a l l , there was probably l i t t l e Figure 1°7. Seasonal changes i n t e s t i s size and h i s t o l o g i c a l structures of 18 adult south Texas peccaries. 65. increase in the t o t a l number of sperm produced. However, at a l l seasons sperm production appeared to be s u f f i c i e n t f o r f e r t i l i z a t i o n . Comparison of h i s t o l o g i c a l structure between the moist and dry years i s tenuous because only one adult from each of s i x corresponding months was examined h i s t o l o g i c a l l y . A one-tailed paired " t " test showed a s i g n i f i c a n t difference only i n the number of sperm (P< .05) between these periods. The number of sperm present i n the dry year was s t i l l much higher than i n males at f i r s t maturity and there can be l i t t l e doubt that males i n the dry period were s t i l l f e r t i l e . The west Texas males followed the same pattern as the south Texas males, although they have fewer sperm and r e l a t i v e l y more i n t e r s t i t i a l tissue (Appendix E). 4.6. Female reproduction 4.6.1. The Reproductive Tract and Mammae. Description of the reproductive tract was based upon the tracts from a 16 month old v i r g i n and a 4 year old, 1 week post-pregnant adult peccary. The uterus was bicornuate. In the v i r g i n adult each horn was about 10.5 cm long, and in the pregnant sow, the cornua reached about 25 cm. The cornua were coiled i n l a t e r a l helices. The body of the uterus of the v i r g i n adult was 3.5 cm from the cervix to the c l e f t of the cornua, and about 8 cm i n the pregnant adult. The Fallopian tubes were straight and short, 9 to 10 cm. The well vascularized fimbriae of the ostium are normally f l a c c i d , but during oestrus, become turgid. They aid not enclose the ovaries. Plate 3a shows the reproductive tract with uterus opened and the foetuses alongside. The foetal attachments are of the diffuse e p i t h e l i o c h o r i a l type (Nalbandov, 1964), with a s l i g h t y l more intimate and zoned placental e p i t h e l i o c h o r i a l i s than i n the domestic sow (Wislocki, 1931). There were 4 pairs of mammary glands i n both south and west Texas peccaries. The two pectoral pairs were l i t t l e more than pigmented spots, but the inguinal and post-abdominal pairs were both functional. In l a c t a t i n g sows, the hind pair was usually larger, but occasionally the post-abdominals were larger. 4.6.2. The Ovary. The ovaries were r e l a t i v e l y large and frequently appeared, b i -lobed because of the presence i n pregnant sows of a large functional corpus luteum bulging from the ovarian body (Plate 3 b,c,d). 66. P l a t e 3. The female r e p r o d u c t i v e t r a c t . a. The t r a c t of a pregnant sow opened to show foetuses. b. The ovary from a non-pregnant sow. Bumps, on surface are f o l l i c l e s . The h i l a r end i s at the top. c. The ovary from a pregnant sow. Two corpora l u t e a bulge from the ovary at the top. F o l l i c l e s w e l l i n g s can be seen i n the body of the ovary. The h i l a r area i s at the bottom. d. The ovary from a pregnant sow. One corpus luteum bulges from the top of the ovary. The h i l a r area i s at the bottom. i 67. 68. The ovary was supported by the fibrous mesovarium to the broad ligament. Frequently one or more f l u i d f i l l e d cysts were present at the juncture of the mesovarium and the ovary. These, were usually under 1 mm diameter but occasionally up to 4 mm, and probably did not influence reproduction, as they were equally abundant i n both pregnant and non-pregnant sows. In the ovary, the medulla and cortex were c l e a r l y distinguishable. The medullary region was separated from the c o r t i c a l region by a very thick tunica albuginea from at least 82-days post-conception (Plate 4a,b). In foe t a l ovaries, the tunica contained many r e l a t i v e l y small blood vessels, but i n older animals i t contained many large arteries and blood sinuses, together with many l i p o c y t i c c e l l s (Plate 4c). The l i p o c y t i c c e l l abundance varied considerably between animals with l i t t l e apparent relationship to pregnancy. These c e l l s were also common i n the mesovarium of most animals. The ovary i n an 82-day conceptus weighed .02 gms and had a volume of .01 cc. I t contained a large medulla, .001 cc (10% of ovary volume), encased in a r e l a t i v e l y wide connective tissue tunic, and a wide cortex f i l l e d with many cords (Plate 4a). A few tubule ' f o c i ' were v i s i b l e i n the medulla, and associated prominently with the medulla i n the h i l a r area was the rete o v a r i i , the mesonephric urogenital connection. By 115—days post—conception, the medullary tubules had increased and expanded but the medulla had assumed a lesser portion of the ovary (3.2%). The c e l l s of the tubules appeared to be S e r t o l i c e l l s , as Leach and Conaway (1963) found in the skunk. At b i r t h , the size of the medulla increased s l i g h t l y to 7.2% of the ovary. The medullary tubules were quite obvious, scattered i n clumps (Plate 4 b). The rete was also s t i l l prominent. At 6 months ( s t i l l 2 to 5 months before the f i r s t possible preg-nancy) , the ovary had increased to 0.7 gm, and 0.4 cc, and the medulla to 0.2 cc (50% of ovary volume). Medullary tubules were no longer d i s t i n c t , but the i n t e r s t i t i a l c e l l s were arranged i n an extensive connective tissue reticulum. In none of the adult south Texas or pen—reared sows were the medullary tubules evident, but i n the west Texas c o l l e c t i o n , several of the older sows had d i s t i n c t tubules complete with lumina (Plate 4 d). Microscopic appearance of the i n t e r s t i t i a l c e l l s of the ovarian medulla i n pregnant adults was s i m i l a r to the appearance of the t e s t i c u l a r i n t e r s t i t i a l tissue i n adult boars (Plate 4 e and f ) , and they are no doubt homologous. The rete o v a r i i was d i s t i n c t l y v i s i b l e i n an 82-day conceptus, i n 69. Plate 4. Ovarian structures. a. The ovary of an 82-day old foetus. Note the central medulla surrounded by the connective tissue tunic. The h i l a r area i s at the bottom. b. The ovary of a neonatal peccary. Note the central medulla contain-tubules, and surrounded by the vascularized connective tissue tunic. Cords are v i s i b l e in the cortex. c. Lipocytic c e l l s in the outer edge of the medulla i n an adult female ovary. The medulla extends from the lower and right sides of the picture. d. The medulla of a 9-year old west Texas sow containing tubules. e. The medulla of a non-pregnant sow. Note l i p o i d granules in the ' i n t e r s t i t i a l ' c e l l s . f. I n t e r s t i t i a l c e l l s of the t e s t i s of an adult male. g. The rete o v a r i i (lower right) i n a 9-year old west Texas sow. The medulla i s the upper portion of the picture. h. The rete o v a r i i i n a f o e t a l peccary. The h i l a r area i s to the righ t , and the cortex forms the top and bottom projections. The medulla i s to the l e f t . 70. 71. a 9-year old south Texas sow (Plate 4 g and h) and at several ages between. I t was nearly always connected with the medulla. The rete was more prominent i n a l l of the west Texas specimens than i n most of the south Texas and pen-reared specimens. The c o r t i c a l region of the ovary followed the normal mammalian pattern of development. Cords were prominent i n the 82-day conceptus, and these cords could have been developing out towards the periphery, as Gropp and Ofino (1966) have suggested for c a t t l e . A more intensive series should be examined to ascertain t h i s point. The cords remained prominent u n t i l a f ter b i r t h . By b i r t h , the primordial f o l l i c l e s were present and formed a d i s t i n c t band around the periphery of the ovary (Plate 5a). Appendix F (Tables 1 and 2) l i s t s the age-specific weights and volumes of the ovaries and the volumes of the medulla, corpora lutea and largest f o l l i c l e s of non-pregnant and pregnant sows from south Texas and from west Texas. The ovary increased i n size to 1.1 gm at 5 or 6 years and decreased s l i g h t l y there-af t e r . The size of the medulla fluctuated widely but appeared to be at i t s largest size between 1 and 5 years, after which i t gradually decreased. Since the size of the ovary increased to 5 years, the r e l a t i v e size of the medulla decreased from 40°/o at 1 year to 18°/Q at 7+ years i n south Texas, and 50°/o at 1 year to 15°/o at 7+ years i n west Texas. There was no s i g n i f i c a n t difference i n ovarian medulla size of sows 2 years old and over between pregnant and non-pregnant animals (P <. .4) or between west Texas and south Texas sows (P < .5). The seasonal change i n medulla size for a l l sows 2 years and older i s shown i n Fig. 18. The pattern i s obscure, but mid-summer size tended to be larger than winter si z e . The appearance of the i n t e r s t i t i a l c e l l s did change with pregnancy state. In preg-nant animals with functional corpora lutea, the medullary c e l l s appeared more regressed and contained more brown l i p o i d granules than i n the non—pregnant sows where the c e l l s appeared to be generally large, s l i g h t l y vacuolated, and secretory (Plate 5 b and c ) . The l i p o i d granules were present i n a l l adult medullas, and i t i s probably these that impart the dark brown to balckish color to Bouin 1s-fixed medullas. The structure was highly vascularized at a l l times, and had an extensive connective tissue reticulum. The c o r t i c a l region surrounded the medulla (Plate 5d). Clustered sub-adjacent to the germinal epithelium were numerous nests of primordial f o l l i c l e s (Plate 5 a ) . In the stroma, were found f o l l i c l e s i n several stages, 72. Plate 5. Ovarian structures. a. Primordial f o l l i c l e s i n a band around the periphery of the cortex. b. The medulla of a pregnant sow. c. The medulla of a three month post-pregnant sow. Note the great-er granularity of the c e l l s . Blood vessels are at the top of t h i s and the preceding picture. d. A section of the ovary showing the structures present. At right center i s the medulla surrounded by the vascularized tunic. F o l l i c l e s in various stages of development are i n the cortex. A newly framing corpus luteum i s present at the l e f t center, and a scar formed from a degenerating f o l l i c l e i s present at bottom right cerater. The h i l a r area i s to the r i g h t . e. A degenerating corpus luteum of non—pregnancy. Note the gen-eral absence of large blood vessels. f. A degenerating corpus luteum of pregnancy. Note the pigmen-tation and vascularity. g. A newly—forming corpus luteum of pregnancy. Ovulation occurred four days previously. The medulla i s to the l e f t . h. Granulosa l u t e a l c e l l s in•a degenerating corpus luteum. Note the honeycomb structure caused by vacuoles i n most of the c e l l s . One c e l l at top center shows the normal heavy s t a i n -ing of most of the granulosa l u t e a l c e l l s during pregnancy. i . A scar of a recently-past pregnancy. The brown pigmentation shows up well i n coloured material. At t h i s stage the scar i s mostly connective tissue with enclosed blood vessels. A f o l l i c l e i s v i s i b l e on the r i g h t , and the c o r t i c a l stroma on the l e f t . A few primary f o l l i c l e s are v i s i b l e around the periphery of the ovary at the top. 73. Y O L U : ME (mmJ) mean t . 0 5 S E 300 200 100 0 Jan Feb Mar Apr May Jun J u l Au.£ n=3 n=ll n=7 n=5 n=5 n=10 n=6 n=l Sep Oct Nov n=5 (3=5. n=19 F i g u r e 1g :. Seasonal changes i n s i z e of o v a r i a n medulla f o r a l l sows older than two years c o l l e c t e d i n south Texas. Values given are mean, standard e r r o r at the t l e v e l , and the Eange. 75. corpora lutea of pregnancy or non-pregnancy, scars of pregnancy (= corpora a l b i c a n t i a ) , and non-pregnancy, degenerating f o l l i c l e s , diffuse i n t e r s t i t i a l c e l l s (which i n some pregnant animals take on a l u t e a l appearance), con-siderable amounts of connective tissue, and blood vessels. B r i e f l y , the ovarian changes associated with the cycles of oestrus and pregnancy i n the peccary were as follows. In an oestrus cycle many primordial f o l l i c l e s developed into primary f o l l i c l e s . Of these, a high percentage became a t r e t i c and the remainder enlarged into the subadjacent stroma. There was a high mortality rate of f o l l i c l e s throughout the process, and only 10 to 40 f o l l i c l e s per cycle grew to a size greater than the 1 .5 mm diameter t e r t i a r y f o l l i c l e . Of these, usually two, but sometimes three or one, developed to a diameter greater than 3 mm and ovulated at 4 to 6 mm diameter. The largest f o l l i c l e s found were in the ovaries of a pen-raised sow, that had gone through two oestrus cycles while l a c t a t i n g , and was just entering a t h i r d oestrus. The f o l l i c l e s were 5.4 mm and 4.8 mm average 3 diameter with volumes of 80.2 and 57.6 .mm . Cycling of new f o l l i c l e s continued even i n pregnant sows. How-ever, the f o l l i c l e s seldom reached 3 mm diameter before becoming a t r e t i c . A few (one to four) of the large f o l l i c l e s became lu t e i n i z e d and formed accessory corpora lutea at any time during pregnancy, though most commonly during the early stages. Luteinization i n these cases occurred i n both ovulated and unovulated f o l l i c l e s . When f o l l i c l e s ovulated during oestrus, they immediately f i l l e d with l u t e a l tissue whether or not. the sow had been impregnated (Plate 5 g). I do not have any direct evidence of the length of time that the corpus i s maintained i f pregnancy does not occur i n peccaries, but i n pigs i t appears to be 14 days (Corner, 1915, 1921). These corpora lutea of non-pregnancy (CL-NP) did not a t t a i n a size as large as corpora lutea of pregnancy (CL-P) (see Appendix F, Tables 1 and 2). Furthermore, they did not become as well vascularized or pigmented as did CL-P (Plate 5 e and f ) . Thus, when they degenerated, they persisted for a r e l a t i v e l y short time, and the scar was usually distinguishable from the pigmented vascularized scars of CL-P. The corpus luteum grew very rapidly during the f i r s t three to four weeks i n pregnant sows (Fig. 19). The age of the CL-P was determined from the calculated age of the conceptus (Appendix C) except at the 0 to 14 day .7.6.. VOLUME (mm3) 1000 ^_/range mean - t SE J05 500 I CH^JO-14 15-45 60-80 85-115 120-term AGE n = l l n=3 n=8 n=14 n=l3 (d a y S) Figure 19. Changes i n the volume of the corpus luteum of pregnancy (CL-P) w i t h progress of g e s t a t i o n p e r i o d . 77. stage. At t h i s stage the conceptus i s too small to locate readily, and the CL-P and CL-NP are d i f f i c u l t to d i f f e r e n t i a t e . However, i f the uterus was over 50 gm, the animal was assumed to be pregnant. There was l i t t l e change in the mean size after the i n i t i a l rapid growth u n t i l the l a s t month before p a r t u r i t i o n when there was a s i g n i f i c a n t increase in the volume of the CL-P (Fig. 19). The increase appeared to be caused by hypertrophy of the granulosa l u t e a l c e l l s . The largest CL-P i n the paired ovaries for which a corresponding conceptus was found ranged from 200 mm^  to 1049 mrrp. Wislocki (1931) has described the cytological appearance of the corpus luteum of pregnancy. I t has the appearance shown i n Plate 5 h". Blood vessels were well established throughout the corpus, not as i n CL-NP where the larger vessels were mainly near the periphery. The granulosa l u t e a l c e l l s became increasingly pycnotic through gestation, so that by term, most of the granulosa l u t e a l c e l l s stained very deeply. In viable corpora, the granulosa l u t e a l c e l l s were generally not vacuolated, or i f so, then the vacuoles were very small. How-ever, i n non—viable corpora lutea, the l u t e a l c e l l s had a honeycombed appear-ance (Plate 5 h). After p a r t u r i t i o n , the corpus regressed within two weeks to a mean volume of 140 mm^  (Fig. 20). Shrinkage occurred primarily through loss of cytoplasm, and compaction of blood vessels (Plate 5 f and h). The scars of pregnancy were heavily pigmented and stained brown to tan i n Masson's trichrome s t a i n . In ovaries which had been fixed i n Bouin's Solution and sectioned by hand, the scars also appeared dark brown. Scars of past pregnancy were d i s t i n c t l y v i s i b l e i n ovaries of non—pregnant animals, and with experience could be distinguished from scars of CL-NP. Scars of degenerate f o l l i c l e s were also distinguished by t h e i r lack of pigment and blood vessels. In pregnant animals, p a r t i c u l a r l y those having two corpora i n one 'ovary, the compression and displacement of c o r t i c a l structures i n the ovary.was extreme, and distinguishing and counting scars became d i f f i c u l t and unreliable. 4.6.3. The Reproductive Cycle Oestrous Period and Cycle Wide variation was present i n the lim i t e d data obtained on oestrous cycles. Five determinations of the length of the cycle i n one sow averaged 26 days with a range of S to 42 days. S i m i l a r l y , four determinations of the duration of oestrus averaged 5.8 days with a range .78,. F i g u r e 20. R e g r e s s i o n o f t h e c o r p u s l u t e u m o f p r e g n a n c y (CL-P) a f t e r p a r t u r i t i o n . 79. of 3 to 9 days. The frequency of mating of two.young sows cast doubt on the method f o r determining oestrus periods f o r some individuals; however, for most adults i t i s probably v a l i d . Ovarian structures indicated that some, but not a l l , wild pec-caries were polyoestral. throughout the year. CL-NP were found at a l l months of the year with consecutive scars of past oestrous periods i n many cases. In several sets of ovaries, scars of corpora lutea of non-pregnancy of at least threeigenerations were present covering a period of at least 2 1/2 months. I t was possible that these could have been"silent" heats; t h i s might thus explain the fact that the animals had not been impregnated. On the other hand, i n the captive colony, there were several instances of copulation that did not lead to pregnancy. This i s not unexpected on the basis of information from other species. A 5 1/2 year old sow collected i n February, 1967, s t i l l i n the-major breeding period during the drought, had not had an oestrous cycle f o r at least 3 months before c o l l e c t i o n . Another sow, 8 1/2 years old, collected i n October, 1965, just before the major breeding season during the year of good range conditions also had not cycled f o r at least 3 months before c o l l e c -t i o n . Ovarian f o l l i c l e s were s t i l l cycling i n these animals, and 19 and 22, respectively, old'scars of past pregnancy were present i n the paired ovaries. In view- of jthe many factors that can contribute to f a i l u r e to ovulate, 'these two instances do not c l a r i f y the f i e l d circumstances that control ovulation. Gestation Period The length of pregnancy of 13 captive peccaries averaged 144.3 days (range '140 -.147 days, Sx = 0.6). Seven .periods were recorded f o r one sow; they ranged from 141 to 147 days with a'mean fo 144.6 days. Frequency of Gestation An .intensive e f f o r t was made to determine the i n t e r v a l between par t u r i t i o n and post-partum oestrus, and to determine the frequency of f e r t i l -i t y of the post-partum oestrus. Post partum oestrus i s -here defined as an oestrus occurring within two weeks of p a r t u r i t i o n . Sows were presented to boars on nine occasions during the post-partum period ("Table 19). Copulation took place on seven of these occasions. On two of four occasions, when the sow was introduced to the boar on the f i r s t day after p a r t u r i t i o n , copulation ensued. On both occasions the copulation / Table 19. Interval I between parturition and oestrus in; pen-reared peccaries • Previous oppor-Partur i t i o n 1 st F e r t i l e Days, post- tunity, days post-Sow Date Mating 7 partum Lactating partum UBC 4 1D-IV-66 3-V No 23 Yes No (Pc 18D) 17-V Yes 37 Yes Yes 5-X-66 29,30-XI Yes 55,56 Yes No 24-IV-66 25,26-IV No 1, 2 Yes No 4-V Yes 10 Yes Yes 25-IX-67 26-IX No 1 Yes No 2,3-X Yes 7,8 Yes Yes 25-11-68 1,4,5,7,8-111 Yes 5,8,9, ,11, 12 Yes Yes, 2,3 30-VII-68 19,21-VIII No 20,21 Yes Yes, • 17 27,30-11 Yes 58,59 ? Yes 22-11-69 27 - 1 1 Yes 5 Yes Yes, , 3 UBC 391 12-X-67 16-X No 4 Yes Yes, (Pc 168) 24-X No 12 Yes Yes 2-XI No 21 Yes Yes 7-XI No 26 Yes Yes 15-1 Yes 95 No Yes UBC 393 8-VII-68 17-VII No 9 No Yes, , 2, 4,7 13-VIII No 36 No Yes 26-VIII No 49 No Yes UBC 394 24-VI-68 28-VIII Yes 65 No Yes, , 1, 2,3,8,11,16,17,20, 22 :,24 19-1-69 5-II ? 17 Yes Yes, , I C 1,12,14 UBC 397 19-1-69 28,29-1 Yes 10,11 No Yes, , 2, 5 81 . plug was l o s t . On f i v e of seven occasions the post-partum mating resulted in pregnancy. The i n t e r v a l from parturition•to f e r t i l e mating was 5 to 12 days. The frequency of pregnancy of wild animals was determined from pregnant animals that showed evidence of either l a c t a t i o n or recent scars of previous pregnancies (corpora a l b i c a n t i a ) . Only four sows, a l l from south Texas, were collected that were pregnant and s t i l l l a c t a t i n g (Table 20). They varied i n post-conception time from 20 to 125 days. P-10 was 4 months post-conception,- indicating about 4 1/2 months since p a r t u r i t i o n , and s t i l l l a c t a t i n g . Several captive sows were s t i l l l a c t a t i n g when the young were weaned at 3 months, and one at 3.7 months. Most of these captives were pregnant while s t i l l l a c t a t i n g . An additional eight south Texas sows were found to have gone from one pregnancy into the next, either d i r e c t l y , or f i r s t through an i n f e r t i l e oestrus (Table 20). This was determined from ovarian analysis. Scars more recent than 4 to 5 months are s t i l l regressing, and CL-NP and CL-P scars are usually distinguishable. In addition, three sows that were l i v e -trapped with young had produced young i n both spring and f a l l at intervals of 6 months (2) and 5 1/2 months ( l ) i n 1965. Only two of the west Texas animals showed signs of possible consecutive pregnancies. Both of these were i n preimplantation stages so i t was not passible to determine i f the corpora lutea were corpora of pregnancy or non-pregnancy. 4.6.4. Maturation The youngest age at conception was 11.3 months and the youngest animal to copulate was a 10.2-month old, 37 pound female (Table 21). Both of these were pen-reared. The ovarian analysis'showed that f o l l i c l e s began cycling by 7 months i n one south Texas female, and the f i r s t corpora lutea of non-pregnancy scars were backdated to an age of about 7 1/2 months i n a 10-month old g i l t . The youngest pregnant animal collected "in south Texas was 24 months old. Table 20. Incidence of consecutive pregnancies i n south and west Texas peccaries. of Post-conception Conception Evidence of No. Date Age Foetuses Age date prev. preg."* South Texas P-10 21-IV-65 8 yr 1 125-128 days 15-XII-64 Slight amount la c t a t i o n P-14 27-VI-65 6 yr 1 46 days 6-V-65 Lactation; CL-P scar 2-3 mo. old; CL-NP scar 2 mo. old P-21 2-VII-65 5 yr 2 20- 35 days 7-VI-65 Not l a c t a t i o n ; CL-P scar; no CLNP scar P-31 23-VIII-65 3 1/2 yr 1 20- 25 days 1-VIII-65 Lactating; CL-P scars; no CL-NP scar; direct preg P-32 27-VIII-65 6.5 yr 2 88- 93 days 29-V-65 Not l a c t a t i n g ; CL-P scar; No CL-NP scar P-35 15-IX-65 5.7 yr 2 115-121 days 20-V-65 Not la c t a t i n g ; CL-P scars CL-NP scars P-SO 7-II-66 6.0 yr 2 82- 87 days 16-XI-65 Not l a c t a t i n g ; CL-P scars P-81 18-V-66 10.0 yr 2 130-137 days 6-1-66 Not la c t a t i n g ; CL-P scars 4 mo. old P-9S 15-VI-66 8.2 yr 2 89 days 18-111-66 Not l a c t a t i n g ; CL-P 4 mo. old P-III- 8-VIII-66 7.2 yr 1 108-113 days 19-111-66 Not la c t a t i n g ; CL-P scars no CL-NP (2 y) scars - • P-130 22-V-67 2 50 days 1-Iv-67 Not la c t a t i n g ; CL-P scars no CL-NP scars P-140 15-VI-67 (5 y) 2 52- 60 days 20-IV-67 Lactating; caught 8 wk. old young; CL-P scars; Direct preg preg. West Texas BG-6-43 10-XII-66 4.8 yr ? preimplant XI-66 Not l a c t a t i n g ; t h i s i s 1st cycle since p a r t u r i t i o n ; possibly CL-NP? BG-6-52 12-XII-66 5.4 yr ? preimplant XI-66 Not la c t a t i n g ; 1st or 2nd cycle since p a r t u r i t i o n ; poss. CL-NP? — — — — — — — , 03 Note: * CL-P scars = CL-P degenerating but less than three to four months old. 83. Table 21. Behavioural maturation of pen-reared peccaries. Age from Age at Age at Age at Length of Animal which Boar F i r s t F i r s t F i r s t F i r s t No. Available. Copulation Conception Pa r t u r i t i o n Gestation. UBO -4 (Pc 180J 10.0 mo. 10.2 mo. 12.5 mo 17.4 mo. 144 days UBC 391 (Pc 168) 11.1 mo. 11.7 mo. 13.5 mo. 18.4 mo. 146 days UBC 393 7.9 mo. 12.6 mo. 16.6 mo. 21.2 mo. 144 days UBC 394 7.9 mo. 11.3 mo. 16.3 mo. 20.9 mo. 140 days UBC 395 11 .4 mp. 11.4 mo. UBC 397 9.2 mo. 11.3 mo. 11.3 mo. 16.1 mo. 143 days UBC 401 (Pc 181) 14.6 mo. 14.9 mo. 15.1 mo. She was about 52 days post-conception and had conceived at about 2, 2 months in February. Of eight females 12 to 22 months old, only one had scars of pregnancy i n the ovaries. She would have conceived at 16 months old i n January during a minor, drought. The ovaries of three g i l t s collected during good range conditions and four g i l t s collected during the severe drought, a l l 12 to 18 months old, showed no evidence of recent oestruses. In addition, the ovaries of two 2—year old g i l t s collected l a t e ' i n the drought showed no evidence of recent ovulations. A l l other animals over 2 years old had been pregnant before. Maturation of the west Texas females showed the same retarded pattern as the south Texas females. When compared with the captive animals, the youngest female with f o l l i c l e s larger than 1.5 mm was about 8 months old, and the young-est pregnant animal collected, about 3 months through gestation, was 24 months old. Four other sows between 24 and 28 months had produced young 2 to 4 months e a r l i e r . They had a l l conceived during winter when they were about 16 months old. However, none of the three g i l t s between 12 and 18 months old, collected during the f a l l hunt, showed ovarian evidence of pregnancy, and none of the 11 females 12 to 22 months old was reported pregnant by the hunters. 4.6.5. S e n i l i t y Five sows older than 12 years were collected, the oldest 15 years old. Three of these were pregnant; the oldest two (15 and 14 years) with twin foetuses, and a 12 year old with one foetus. These three animals had each ovulated two ova. The other two sows (13 and 12 years) each had three new corpora lutea at the preimplantation stage. The 12 year old's ovaries 84. contained large amounts of connective tissue and she had gone through two oestrus cycles without becoming pregnant, although she had been pregnant more than 4 or 5 months before. Ovaries from two west Texas sows estimated at 9 years or older were collected. One of the sows was pregnant, but had only one foetus. The few scars present suggest that she had been ovulating only one ovum per oestrus for a considerable time. The other had two CL-NP and had gone through 3 oestrus cycles, prior to the present one, since she had been pregnant. 4.6.6. Breeding season Although sows were found at various stages of pregnancy at a l l months of the year, there was a major breeding season for the wild animals. In south Texas the peak conception time, determined by backdating from foetus size was during early winter with a secondary conception period i n spring (Fig.21). Over the three years of the study there were variations i n the exact time of peak p a r t u r i t i o n . During late 1964, minor drought con-ditions prevailed, and sows conceived i n l a t e January, February and March. This brought a peak p a r t u r i t i o n i n May and June (Fig. 21) although f i e l d observations showed the peak i n June and July (Fig. 22). Many animals con-ceived i n late spring, including immediate rebreeding of 40% of the sows that had already produced young that spring. There was another minor peak i n p a r t u r i t i o n i n l a t e f a l l and winter. In 1965-66 conceptions started i n December and peaked i n January and, because of good range conditions, most of the adult sows conceived. This e a r l i e r conception peak resulted i n p a r t u r i -tion peaking e a r l i e r , i h A p r i l (Fig. 21 and 22). Conceptions occurred again i n the spring, but range conditions became very poor over the summer and lack of r a i n resulted i n almost no forage production i n the f a l l . Conse-quently, although there was a minor p a r t u r i t i o n peak i n September (Fig. 22), survival of young was p r a c t i c a l l y n i l . Coincident with drought conditions, there were p r a c t i c a l l y no conceptions during the summer of 1966, consequently almost no newborn young were seen i n the f i e l d from October u n t i l May, 1967. Range conditions remained poor, and conceptions did not occur u n t i l December, 1966 and only a small portion of the sows conceived during January, February, and March. The peak i n p a r t u r i t i o n , although only minor, occurred i n A p r i l or May, although f i e l d observations showed the peak i n May and June. Although a few young were born during the spring of 1967, survival was poor. No con-ceptions were found to occur during the summer of 1967. Reproductive Index (Foetuses/lOO adult 9) Figure 21% Seasonal changes i n the breeding a c t i v i t y of adult female peccaries i n south Texas. CD cn Figure 22. Approximate birthmonth of young peccaries on the Welder Refuge and the King Ranch determined from periodic observations and backdating to the birthmonth of young less than 6 months old. The bars represent the percent of that years' young born during that month. The sample size, n, includes some recounts of individuals. Observations were made during the months underlined. PER CENT OF YEAR'S YOUNG BORN IN MONTH '•aa, 88. In west Texas, the breeding season also appeared to extend through-out the year. However, par t u r i t i o n peaked during the la t e spring and summer months (Fig. 23). One of two adult sows collected i n January, 1966,on the Watson Ranch was less than 3 weeks post—conception. Three adult sows were collected i n June, 1966. One had given b i r t h the night before, another had produced young less than a week before, and the t h i r d was three months post-conception. Another adult collected i n September, 1966, was l a c t a t i n g , and had a 3-month old young with i t . Thus, par t u r i t i o n occurred i n May and June, and conceptions took place between early January and l a t e March. In 1965, there was r e l a t i v e l y l i t t l e r a i n f a l l , and no evidence of pregnancy i n the November-December Black Gap c o l l e c t i o n . In addition, none of the sows even showed ovarian evidence of recent ovulations. The Watson Ranch animals,- as shown, did not mate u n t i l January to March, 1966. However, after good summer and f a l l rains and improved range conditions i n 1966, the November-December Black Gap c o l l e c t i o n showed 25% of the adult sows pregnant. One of these sows was approaching term, and the other three were i n earfl-y^preg— nancy. In addition, three other sows had ovulated 2 to 3 weeks previously, but had probably not conceived. Observations of free-ranging peccaries on the Watson Ranch v e r i f y • the breeding season determined by the reproductive tr a c t analysis. Back-dating to.the b i r t h date of animals less than 1/2 year old showed a complete picture only f o r 1966. Eighty—two percent of the 17 young observed were born in May and June, corresponding with a January—February mating period. Other young were born i n March (12%) and October (6%). A ..comparison of t h i s sort assumes that mortality rate remains r e l a t i v e l y constant through the year. Be—" cause mortality of young born i n l a t e f a l l or winter was probably higher, the proportion of young born at that time was probably under-represented in„Fig.23. However, since observations and collections were made pe r i o d i c a l l y through the year any strong bias should be detected. Observations were made during only parts of 1965 and 1967 and i t was not possible to determine the percentjof young born at monthly i n t e r v a l s . In 1965 many young were born i n the summer and f a l l . On the Black Gap area, hunters reported 17 young between 3 and 6 months old, but no red young (<• 3 months) i n Nov.-Dec, 1965. In contrast, i n the November-December 1966 hunt, they reported 11 red young and eight 3-te month olds. These data do not indicate the strength of the spring increment of young i n either year. I t appears that i n 1965, the births were concentrated i n 89;. 75 50 O 0 o CD PH 3 KJTJ M J' J' A'S' o" N' DI J' F'M' A'M' J' J' A'S" O'N' Dl J ' F'M' A'M'J ' J ' A'S' 4 3 12% 1965 (N = 10) 1966 (N = 17) 1967 ( N = 3) Figure.-|§'.. Birthmonth of young peccaries in west Texas. See legend for Figure 21. 90. early summer, and in 1966, with better range conditions over a longer period of time, births were scattered over a longer period throughout summer and early f a l l . I t i s l i k e l y that the large number of red young present i n the f a l l of 1966 represented a successful second breeding during that year. 4.6.7. L i t t e r Size The average l i t t e r s i ze throughout the study was 1.81 foetuses. Table 22 l i s t s the d i s t r i b u t i o n frequency of l i t t e r s i z e . One of the wild sows with three viable foetuses had a mummified foetus present; thus four embryos had implanted. There were s l i g h t differences i n frequency of multiple l i t t e r s between wild and pen-born l i t t e r s . Table 22. Percentate frequency of l i t t e r s i ze in peccaries. Values are percentages Area No. foetuses Probability of s i m i l a r i t y 'I ^ 3 q n  South Texas wild 30 68 5 34 —\ n.s. — South Texas pen-born 28 56 17 18 Arizona wild 17 50 33 24 Arizona pen-born 4 84 8 4 25 1 ] P = .25' P < .1 P = .5 Captive animals produced 17% t r i p l e t s whereas wild sows had 5% t r i p l e t s i n utero. However, t r i p l e t s were seen only once i n the wild and these were less than two days old. 4.7. Productivity 4.7.1. Ovulation Incidence Ovulation incidence, the number of ova shed at oestrus, was determined from counts of corpora lutea of pregnancy, or from the most recent scars of pregnancy or non-pregnancy. I t was assumed that each corpus luteum represented only one ovum. Polyovular f o l l i c l e s were not uncommon i n the ovaries, but none larger than 2.5 mm diameter was observed. Brambell (1956) indicates that polyovular f o l l i c l e s seldom mature. Although older sows did tend to have a s l i g h t l y higher ovulation incidence than young sows, there was no s i g n i f i c a n t change with age (Table 23). The mean ovulation incidence of a l l sows 2 years and older was 2.2 ova/oestrus i n south Texas, and 2.0 ova/oestrus i n west Texas. The difference was not s i g n i f i c a n t . That i s , when ovulation occurred, sows from both regions to Table 23. Age-specific pregnancy, ovulation and implantation incidence of south and west Texas, and pen—reared peccaries. Notes: a= t o t a l number of ovulations at the most recent ovulation; determined from CL-P, CL-NP, and corpora albicantia/number of animals possessing evidence of ovulation = average number of ovulations per animal (range). b=total number of foetuses found/number of sows possessing v i s i b l e foetuses = foetuses per pregnancy (range), i . e . implantation incidence. c=numbers refer to difference between ovulation and implantation incidence, and the degree of significance. Age Area Proportion Proportion Ovulation Incidence Foetuses per Comments 1-1 .9 S.Tx. 0/7 0 1/7 15 2/1 2.0 (2) — —  6 virgin W.Tx. 0/3 0 0/3 0 0/0 0/0 3 virgin Capt. 8/8 100 2/1 2.0 (1) 16/9 1 .8 (1-2) 2-2.9 S.Tx. 2/7 29 3/7 43', 10/5 2.0 (2) 4/2 2.0 (2) 2 virgin W.Tx. 2/14 14 10/,14 71 23/12 1 .9 (1-2) 3/2 1 .5 (1-2) 2 virgin Capt. 4/5 80 1/5 20 7/3 2.3 (2-3) 8/5 1 .6 (1-2) 3-3.9 S.Tx. 5/7 71 2/7 29 14/7 2.0 (1-3) 5/3 1 .7 (1-2) .33 , P<.5 W.Tx. 0/2 0 2/2 100 4/2 2.0 (2) 0/0 Capt'. 1/1 100 4/2 2.0 (1-3) 4-4.9 S.Tx. 3/4 75 1/4 25 8/4 2.0 (2) 4/2 2.0 (2) 0 W.Tx. 2/5 40 3/5 60 10/5 2.0 (2) 2/1 2.0 (2) 0 Capt. 2/2 100 3/1 3.0 (3) 6/2 3.0 (3) 5-5.9 S.Tx. 8/11 73 3/11 27 23/10 2.3 (2-3) 15/7 2.3 (2-3) .14 P<.4 W.Tx. 1/2 50 1/2 50 4/2 2.0 (2) 0/0 6-6.9 S.Tx. 5/6 83 1/6 17 11/6 1 .8 (1 .3) 8/5 1 .6 (1-2) •2, P=n.5. W.Tx. 0/2 0 2/2 100 2/1 2.0 [2) 0/0 7-7.9 S.Tx. 2/2 100 0/2 • 4/2 2.0 [2) 3/2 1 .5 (0-2) .5, P<.5 8-8.9 S.Tx. 4/5 80 1/5 20 8/4 2.0 (2) 6/4 1 .5 (1-2) •5, n.s. 9-9.9 S.Tx. 5/6 83 1/6 17 16/6 2.7 (2-4) 7/4 1 .8 (1-3) • 9, n.s., + 1 resorb.,1 abori W.Tx. 1/2 .- 50 1/2 50 3/2 1 .5 (1-2) 1/1 1 .0 ( 0 .5, n.s. 10-15 S.Tx. 7/8 88 1/8 12 19/8 2.4 (2-3) 9/5 1 .8 (1-2) .6, n.s., + 1 resorb. 7+ S.Tx. Preg.sows 3D/13 2.3 22/13 1.7 .6, P< .D1 UnKn.Ad. S.Tx. 1/2 50 1/2 50 4/2 2.0 (2) o/o W.Tx. 0/2 0 2/2-'-100 5/2 2.5 (2-3) o/o Total 2+ yrs. S.Xx. 42/58 72 14/58 24 117/54 2.2 (1-4) 61/34 1.8 (1-3) .38, P <C .002 W.Tx. 6/29 21 21/29 72 51/26 2.0 (1-3) 6/4 1 .5 (1-2) .46, P = n.s. 93. produced abouth the same number of ova. Since there was no difference i n ovulation incidence between south and west Texas, a change i n ovulation incidence i n south Texas from good r a i n f a l l to poor r a i n f a l l periods was not expected, and t h i s proved the case. Ovulation incidence i n a l l adult sows i n the good r a i n f a l l period was 2.17 + .10. ova/oestrus, and i n the poor r a i n f a l l period 2.2 + .12 ova/oestrus (n.s., P = .5). In the pregnant sows, the incidence was 2.13 ova/oestrus i n the good period, and 2.14 i n the poor (Table 24). 4.7.2. Implantation Incidence I t appeared that the period between ovulation and implantation was the time of greatest intra-uterine mortality. Average losses of embryos prior to implantation were determined from 34 sows i n the post-implantation stage of pregnancy by subtracting the number of foetuses from the number of corpora lutea of pregnancy. These '.lo.sses t o t a l l e d 17.5% (P< .002) .over the study period i n a l l south Texas sows two years and older (Table 23). The loss of embryos before implantation i n 21 sows less than s i x years old was not s i g n i f -icant, but i n 13 animals over 7 years, the rate of f a i l u r e to implant was 26.7% (P < .01) (Table 23). Only three cases of foetal mortality were found i n 42 south Texas sows examined af t e r the "implantation" stage. One of these was mummification of one of four foetuses, a second was resorption of one of three foetuses, and the t h i r d was abortion of a l l foetuses. In west Texas, only four sows with foetuses were collected. The sample i s too small for;''a r e a l i s t i c comparison with the south Texas c o l l e c t i o n , but 25% of the ova f a i l e d to "implant". A s l i g h t l y better indication of the effect of adverse climatic con-ditions on implantation was available i n comparison of the implantation rate i n the moist and drought periods i n south Texas. The time at conception was used to determine which period the implantation occurred i n , and only the moist period from June, 1965 to June, 1966, and the drought period from July, 1966 to August, 1967 were used. During the period of good range conditions the ovulation incidence of 28 sows with foetuses was 2.17 + .10 ova/sow, and the implantation incidence. 1.88 + .13 foetuses/sow. In the drought period i n only 6 sows, ovulation Incidence was 2.2 + .12 ova/sow and the implantation incidence was 1.67 + .21 foetuses/sow. The differences i n ovulation and implantation 94. Table 24. Seasonal ovulation and implantation incidences, and reproduc-t i v e index i n south Texas peccaries, 1965 to 1967. Period Proportion Corpora Lutea c  pregnant no"! n no/100 Jo no! n Preg. ad. F. F. Implantation Incidence no. foetus/ foetus 100 CL Reproductive Index Foetuses/100 ad. sows quarterly half-yearly 1965 Jan-Mar100 1 1 12 6 200 200 9 75 150 Apr-Jun100 10 10 16 7 229 229 15 94 215 x = 185 Jul-Sep S3 5 6 4 d 2 200 166 3 75 125 Oct-Nov 25 1 4 1 6 d 7 229 57 12 92 52 x = 116 Total 81 17 21 48 22 218 177 39 87 x = 154 = 301/yeai 1966 Jan-Mar100 10 10 13 6 217 217 11 85 184 Apr-JunlOO 4 4 1 1 100 100 1 100 100 172 Jul-Sep 17 1 6 - 1 - — — - -Oct-Dec 33 1 3 3 2 150 50 3 100 50 33 = 205/ Total 71 16 23 17 9 189 134 88 X 118 year 1967 Jan-Mar 40 2 5 8 d 3 267 107 3 50 54 Apr-Jun100 5 5 4 2 200 200 4 100 200 118 Jul-Sep 40 2 5 — — — — - — — Oct-Dec 0 H 0 Total 60 9 15 12 d 5 240 144 7 70 y = ioo = 118/year Total, 1965--1967 H Jan-Mar 79 11 14 33 d 15 220 174 23 74 129 Apr-Jun100 19 19 21 10 210 210 20 95 200 163 Jul-Sep 47 7 15 4 d 2 200 94 3 75 71 Oct-Dec 29 2 7 1 9 d 9 211 61 15 94 57 77 Total 71 40 56 81 d 34 214 152 61 80 X" = 122 = 24£)/-year Total Moist Per i o d 0 83 19 23 34 d 16 213 176 27 87 X 153 = 288 Total Drought Period e 48 11 23 15° 7 214 103 10 77 x 79 = 151 Note : a = number backdated to month of conception = ovulation incidence. b = determined f o r month of conception c = determined by: °/o pregnant when collected X°/o of CL represented by foetuses conceived during that month X no. of CL per preg. sow. d = included i n the figure are some animals collected i n early preg-nancy and embryos were not found i n the uterus. e = moist period i s period of high p r e c i p i t a t i o n and good range cond-i t i o n s , July, 1965 to June, 1966 on th i s table; the drought period extends from July, 1966 to Aug. '67, range conditions poor. 95. incidence between the two periods were not s i g n i f i c a n t . The implantation f a i l u r e rate in the moist period was .29 + .11 ova/sow and i n the drought period was .53 + .34 ova/sow. Because there were only s i x sows collected during the drought that were i n post-implantation pregnancy, the variance i s high during that period, and the difference i s not s i g n i f i c a n t . 4.7.3. Ovulation and Implantation Rates The proportion of sows i n which there were degenerating CL-P as well as functional CL-P was greater i n south Texas during the period of good r a i n f a l l than i n either the drought period in south Texas, ;..or i n more arid west Texas (Table 25). The sample obtained during the mild drought i n the spring of 1965 i s not comparable with the other two south Texas sample periods because i t was a short sample-period taken during a peak partur i t i o n and breeding period. The south Texas c o l l e c t i o n during good range conditions showed that 60D/> of the pregnant sows had ovarian scars of recently past preg-nancy, whereas only 33% of the pregnant sows collected during the period of drought had recently produced young. Of the sows collected during the period of good range conditions, 41% remated, and only 9% remated during the drought conditions. Therefore, ovulation and implantation rates during the period of good range conditions would be 1.41 times the ovulation and implantation incidences. During the drought conditions, the rates would be 1.09 times the ovulation and implantation incidences. The data f o r west Texas animals were collected during such a short period that any inferences of rates would be premature. 4.7.4. Productivity of age classes Young wild peccaries seldom produce a l i t t e r before they are two years old (Table 23), and since I had no measure of the number of young pro-duced by subadults (essentially f u l l grown, but the majority of the cohort have not produced young, Hanson, 1963:8), productivity of t h i s age class must be disregarded. This i s not s t r i c t l y accurate, as a l l of the pen-reared animals had produced a l i t t e r by two years, and the average l i t t e r s i ze was 1.8. The r e l a t i v e contribution by older animals did not change s i g — 4 n i f i c a n t l y with age class, but did show a trend f o r 4-and 5-year olds to be most productive (Table 26). The contribution of each age class to the pro-duction of each gestation period was determined from the proportion of that Table 25. Proportion of adult sows showing evidence of consecutive pregnancies i n south Texas and west Texas during drought and good r a i n f a l l periods. S o u t h T e x a s Wes, t T e x a s Mild drought 3 good pptn'3 drought 0 Total Moist (1966) dry(1965) Total °/o of sows known pregn. 92 (11/12) 71 (17/24) 26 (6/23) 58 (34/59) 25 (4/16) • (0/13) 25 (4/29) °/o pregn. with recent CL-P scars 73 (8/11) 60 ( 9 / l 5 ) B 33 (2/6) 59 (19/32) • (0/4) f • o (d/4) f % t o t a l with consec. pregn, 67 (8/12) 41 (9/22) 9 (2/23) 33 (19/57) • (0/4) f 0 D (0/29) b - good range conditions, June, 1965 to June, 1966. c - severe drought conditions July, 1966 to August, 1967. d - collections primarily in November-December and not comparable to south Texas col l e c t i o n s , e - two pair of ovaries not examined. f — two sows in preimplantation stage and pregnancy not certain. 97. age class i n the population (Table 10) and the reproductive index of each age class (Table 26). I r r e g u l a r i t i e s i n the proportion of young contributed by each age class are caused by small sample s i z e . However, the older age classes contributed a high proportion of the young to the population. Two year olds, by virtue of t h e i r abundance i n the population, and 5 year olds, because of t h e i r higher productivity, contributed the most to the population. Larger sample size ' would probably show a better d i s t r i b u t i o n of contribution among the younger age classes. Because of the small proportion of pregnant sows in the west Texas colle c t i o n s (Table 20), i t was impossible to determine the contribution of young by each age class. However, since the older age classes were v i r t u a l l y absent," the contribution by the younger age classes assumes more importance. Table 26. Age class productivity of south Texas peccaries. Age Sample Young/ °/o of ad. Young/100 ad. contribution Class Size pregnancy population sows / gestation of age class 1 yr 8 7 29 — — — — — — 2 7 2 12 24.0 18 3 7 1 .7 8 13.5 10 4 4 2.0 ,7 14.0 10 5 9 2.25 12 27.0 20 6 6 1 .6 9 14.4 11 7 2 1 .5 3 4.5 4 7+ 20 1 .7 22 37.4 28 63 134.8 101 4.7.5. Gross^Net Productivity The reproductive index (Table 24) was taken as a measure of gross productivity during a three month period. For p r a c t i c a l reasons, the gross productivity f o r a year was taken as the average during the major reproductive period plus the average during the minor reproductive period. Gross prod-u c t i v i t y during 1965 was 301 young per 100 adult sows based on 21 sows. During 1966 i t was 205 young per 100 adult sows based on 23 sows; and, i n 1967,118 young per 100 adult sows based on 15 sows (Table 24). These data represent fluctuations of 25c/o above and 50°/o below the mean during the 3 years of the study. The 1967 estimate i s minimal because collections were not made during the l a s t four months of the year. However, since none of the sows collected p r i o r to termination of the f i e l d work i n August would have reached term during the f a l l , and any sows breeding i n September or l a t e r would have reached term in the next year, the contribution from these four months would have been small. 98. During the period of good range conditions, the productivity was 288 foetuses/100 adult sows and only 151. foetuses/100 adult sows during the drought conditions (Table 24). The gross productivity of the penned animals was 425 young/100 adult sows (n = 7). Thus, there was a marked discrepancy between production of young under relatively "ideal" conditions and that of even the best f i e l d conditions encountered. Net productivity was taken as the proportion of young at heel compared to the number of adult females observed. The age ratio and sex ratio data were used to determine the proportion of the observed animals which were adult females. Table 27 shows the monthly and quarterly sightings of three age classes of young per 100 adult sows. Because of the overlap of classification into age classes, the results must be treated with some res-ervation. However, the trends are s t i l l evident. Survival of young in early 1965, the end of the minor drought, was low. Survival of red young past the neonatal period was quite high in early 1966 following the exceptionally favourable winter. The apparently high survival of red young in 1967 is misleading because most of these were seen within a week or so of birth. Trapping data in this study showed that an average of 29% of the south Texas population over 1 year old were in the 1-to 2-year old group. Using the age ratio and sex ratio data, this would equal a net productivity of 53 animals per 100 adult sows. The less than -1™year olds were 44% of the adult population and equalled net productivity of 81 young per 100 adult sows. By comparison neonatal mortality of pen-reared l i t t e r s resulted in a net produc-t i v i t y of 325 young per 100 adult sows. There was no mortality of pen-reared young after the i n i t i a l neonatal death of 24% of the young. Data for West Texas are meagre and the best estimate of produc-t i v i t y were the 1:to 2 year olds. These comprised 25% of the adult population, and indicated productivity of 45 animals per 100 adult sows. Table 2 7 . Proportion of young animals observed i n population at monthly and quarterly Period No. adults > 1 y r . 1 9 6 5 Jan 2 7 ^ Feb . 9 8 Mar 1 0 0 i n t e r v a l s . Number per 1 0 0 adult females No of y o u n g / 1 0 0 ad.F. quarterly Red young half-grown j u v e n i l e 0 - 3 mo. 3 - mo. 6 — 1 2 mc . 1 9 1 9 3 7 . 9 2 . 5 1 5 . 6 9 9 . 4 5 . 1 2 8 . 7 9 . 4 Red h a l f - juvenile jj young grown 5 . 6 2 1 . 6 8 3 . 1 Apr 1 2 8 ^ May 3 6 ^ June 2 9 2 . 1 2 6 . 2 5 4 . . 1 3 5 . 6 7 . 2 7 1 . 3 9 . 2 6 . 3 9 . 4 2 2 . 7 5 3 . 1 July 6 8 Aug 1 2 3 Sep 7 8 3 7 . 6 1 5 . 2 4 1 . 4 6 . 2 2 5 . 2 1 8 . 7 0 2 6 . 5 5 1 . 6 1 2 . 4 2 3 . 1 3 3 . 9 • c t 7 3 , . Nov 1 3 Dec 9 C 0 2 1 . 4 9 . 2 0 0 0 0 2 8 . 5 8 5 . 4 0 1 8 . 9 4 5 . 9 1 9 6 6 Jan 2 5 C Feb 2 0 1 Mar 1 2 6 0 2 0 . 4 3 0 . 7 4 0 . 8 6 . 8 5 7 . 5 1 4 . 2 3 . 9 2 6 . 3 2 8 . 5 6 . 6 4 4 . 4 Apr 5 4 May 7 8 June 8 3 6 1 . 7 9 . 4 1 4 . 2 2 3 . 1 4 5 . 8 3 9 . 3 1 9 . 2 3 7 . 6 1 2 . 5 3 1 . 3 3 3 . 4 2 2 . 7 July 5 8 Aug 6 6 Sep 1 0 0 2 2 . 2 6 6 . 2 2 6 . 6 3 1 . 1 2 7 . 2 2 3 . 1 1 2 . 8 5 3 . 8 2 0 . 4 2 0 . 7 4 9 . 2 2 2 . 8 Oct 1 3 4 Nov 1 0 5 Dec 1 0 4 ° 7 . 4 3 6 . 3 3 0 . 6 9 . 6 8 7 . 7 5 6 . 1 2 . 4 2 9 . 6 5 1 . 7 6 . 6 5 0 4 4 . 8 , 1 9 6 7 Jan 9 3 C Feb 1 1 2 C Mar 6 0 0 5 . 5 1 4 3 . 2 0 1 1 . 4 5 9 . 4 0 4 . 2 4 6 . 9 0 7 . 7 8 6 . 1 Apr 4 2 ^ May 8 4 June 2 8 9 0 0 4 8 . 7 1 8 . 3 0 3 0 . 4 4 3 . 4 0 2 1 . 3 3 3 . 9 0 2 5 . 9 July 6 4 Aug 1 3 2 Sep 0 1 2 . 1 0 0 5 2 . 4 3 1 . 0 3 9 . 3 2 0 . 8 0 Oct 1 3 U 0 0 1 9 . 7 Note: b = observation only on King Ranch c = observation only on Welder Refuge a = quarterly average determined from cummulative t o t a l s f o r the quarter e.g. Jan-Mar, 1 9 6 5 , 2 2 5 adults observed. The f i g u r e i s based on the number of adult sows greater than 2 years old by subtracting males ( 4 5 % ) and 1 to 2 year olds ( 2 9 % i ) from the number of adults and subadults observed. 100. 5. DISCUSSION The foregoing data show that body condition, growth and reproductive a c t i v i t y of the collared peccary in Texas vary considerably with d i f f e r i n g climatic conditions. On ar i d land ranges, as those on my Texas study areas were, a few inches change i n annual r a i n f a l l can represent a large percentage deviation from the normal. The resulting influence of changes i n r a i n f a l l on vegetation and animals can be profound as shown by studies by Wallmo (1957), Box (1960), Chamrad and Box (1965) and Harper (1969) on plants and White (1966), Marburger and Thomas (1965), Newsome (1966b), Newsome et a l . , (1967), and Ealey and Main (1967), Q n animals. Sadleir (1969:105) stated that i t i s academic to seperate the effects of climate and n u t r i t i o n since climate so closely controls the food supply. Even temporary shortages of r a i n f a l l cause marked decreases in the quantity of green forbs and grasses available, but just as importantly there i s an accompanying decrease i n quality of the vegetation as i t dries out (.Sampson, 1952; M i l l e r , 1966). Conversely, increases i n r a i n f a l l , p a r t i c u l a r l y after a drought, cause immediate increases i n plant growth i f temperature i s favourable (Box, 1961; Harper, 1969). The increase i n nutrient quality of plant material during early growth, and decrease during hot and cold dry periods has been well documented (Sampson, 1952; McLean and Tisdale, 1960). These changes have been demonstrated to occur on the ranges supporting the '.... populations of peccaries studied (Box, 1961). For these reasons I have equated high r a i n f a l l l e v e ls with good range con-ditio n s , and also the converse, p a r t i c u l a r l y since i t was more p r a c t i c a l to make use of r a i n f a l l data than to attempt an analysis and interpretation of changes i n the vegetation i t s e l f . Stomach sample analysis, providing information on forage class.-u t i l i z a t i o n , showed that peccaries are opportunistic feeders and t h e i r diet through the year r e f l e c t s changes i n the plant species and the growth stage available (Fig. 6). Peccaries consume the best quality foods that are available, but always make use of the omnipresent p r i c k l y pear i n south Texas. In west Texas, sotol and lechuguilla as well as p r i c k l y pear take the role of south Texas p r i c k l y pear in the peccaries' diet (Jennings and Harris, 1953). Although s p e c i f i c information on the nutrient quality of the food items found i n the peccary diet i s not available, details of the nutrient quality of some of these items at various stages of growth have been published ( M i l l e r , 195S; Sampson, 1952). Determination of the forage 101 . class composition of the stomach contents at various times of the year and under different climatic conditions can then be used to i n f e r the quality of food consumed. Pr i c k l y pear i s by f a r the most common of the forages used by peccaries in south Texas (Fig. 6 ) , and so t o l , lechuguilla and p r i c k l y pear are the dominant species in west Texas peccary stomachs (Jennings and Harris, 1953). However, they are low i n protein and high i n carbohydrates ( M i l l e r , 1958; Hoffman and Darrow, 1964). Although the stomach of the peccary i s three-parted and more complex than the monogastric stomach of the pig, i t has not yet been shown that fermentation and production of v o l a t i l e f a t t y acids occur i n the peccary stomach (Moir, 1968; L. Sowls, pers. comm.). Thus, although car-bohydrates are always abundant i n the diet, the low protein l e v e l i n the winter diet could be a severe l i m i t a t i o n on the u t i l i z a t i o n of the carb-ohydrates (Maynard and L o o s l i , 1962). With good r a i n f a l l and consequent abundance of high protein forage the animals can be expected to make more effect i v e use of the carbohydrates available in p r i c k l y pear (Maynard and L o o s l i , 1962). Body condition of peccaries followed a seasonal pattern very s i m i l a r to that found i n south Texas w h i t e t a i l deer by White (1966). During part of the same period he also found that the seasonal pattern was strongly influenced by r a i n f a l l over the preceding vegetation growth period. In both species i t was found that high r a i n f a l l , good range conditions, and good animal condition are correlated, as are low r a i n f a l l , poor range conditions, and poor animal condition. Although there i s a lag between each of the events, i t i s not possible to put an absolute value on the reaction period. Suffice i t to say that the response of vegetation to r a i n f a l l occurs within a few days, depending on temperature, and the response in animal condition occurs within a few weeks. Nutrition has important influences on growth and reproduction (Maynard and L o o s l i , 1962). Animals that are undernourished have a slower growth rate than adequately nourished animals, but may s t i l l attain a normal maximum weight (Maynard and L o o s l i , 1962). In peccaries, a slower growth rate would affect the age at maturity and therefore influence the productivity of the indi v i d u a l and the population. An estimate of differences between the populations, i n growth patterns and attainment of adult size and of condition differences between populations and under different climatic conditions showed that the captive animals i n good n u t r i t i o n a l regime out 102. performed the wild animals. There i s an association between the a v a i l a b i l i t y of forages high i n protein and the achievement and maintenance of good body condition. Fat deposits r e f l e c t the n u t r i t i o n a l adequacy and abundance of forages (NAS-NRG, 1962), and, within wide l i m i t s , indicate the physiological condition and reproductive state of the animal (Riney, 1955; Taber, et a l ; 1959). Condition of the ungulates has been commonly assessed by determining the amount of perirenal f a t (Riney, 1955; Ransom, 1965) and although i t i s not s t r i c t l y objective i t appears to be the most p r a c t i c a l method available. Correlation of physical condition with perirenal f a t deposits i s based on extensive f i e l d and autopsy data i n a number of ungulates (Cheatum, 1949; Harris, 1945; Riney, 1955). I assumed that a s i m i l a r relationship also applied to peccaries. Body condition, as measured by kidney f a t , showed a p a r a l l e l relationship with range conditions i n south Texas animals ( c f . Figs. 5, 6 and 7). During the above-average rains i n l a t e 1965 and early 1966, pec-caries had higher kidney fat l e v e l s , and even put on dorsal f a t . During the drought of 1966 and 1967, kidney f a t levels were lower, and there was no dorsal f a t present on the animals (Table 2, Fig. 7). In west Texas, both male and female peccaries were i n s l i g h t l y better condition i n 1966 than i n 1965 because of the better range conditions res u l t i n g from the good d i s t r i b u t i o n of rain through the year (Table 2). Si m i l a r l y , change i n body weight, also p a r a l l e l l e d the general r a i n f a l l l e v e l and range conditions (Table 5). Carcass weights were heavier during the period of good range conditions i n south Texas, and l i g h t e r during the drought. In west Texas, the weights of the males were s l i g h t l y heavier during wetter year, 1966, but females, however, were s l i g h t l y l i g h t e r (Table 5). This was possibly because of the higher rate of pregnancy, and con-sequent energy drain of l a c t a t i o n , which resulted from better range con-ditions i n 1966. Since kidney f a t levels i n west Texas peccaries were lower and carcass weights s l i g h t l y l i g h t e r (despite s i m i l a r body length and height) than south Texas peccaries under poor range conditions, i t appeared l i k e l y that they were i n s l i g h t l y poorer condition. Further evidence of t h e i r poorer condition was the slower growth rates i n the west Texas animals. Even the south Texas peccaries were not l i v i n g i n optimal conditions, f o r they had generally lower kidney f a t l e v e l s , and reached"mature weights l a t e r than peccaries raised i n c a p t i v i t y (Fig. S). Growth rates of peccaries i n c a p t i v i t y and south Texas showed differences consistent with the differences in condition. 103. Captive animals reached adult weights at 18 months, south Texas animals between 2 and 3 years. In s u f f i c i e n t young animals were collected from west Texas to compare growth curves, but they appear to be s i m i l a r to south Texas peccaries. The four peccary papulations studied in Texas generally showed a decrease i n density that paralleled the east-west decrease i n precipitation ( c f , Table 7 and Fig. 1). Peccary populations show a clumped d i s t r i b u t i o n both of individuals and of herds, and no sampling method has yet proven successful for accurately censusing peccaries (Jennings and Harris, 1953; Day, 1962, '64, *65, '66, '67a; E l l i s o r and Harwell, 1969). Only a t o t a l count of a l l animals in a l l herds can give an accurate determination of density, and since t h i s was not p r a c t i c a l , detailed analysis of density changes i s precluded. However, i t was possible to obtain approximations of population size adequate to permit the comparisons necessary f o r t h i s study. A t o t a l count was possible only on the Welder Refuge where the peccary population and the area of the Refuge were small enough and the number of interested persons traversing the area large enough that a reasonable count was obtainable. The density was estimated at 10 peccaries/sq. mile and was considerably less than the estimate of 64 peccaries/sq. mile by E l l i s o r and Harwell (1969) i n an area of good habitat 30 miles northwest of the Refuge. I t should be noted that the Refuge was at the edge of the present geographical ranch of the species, and less than a quarter of the Refuge represents suitable habitat. On the King Ranch, the contagious d i s t r i b u t i o n of the peccary herds i s complicated by brush clearing programs. Complete removal of brush from surrounding areas has caused peccaries to concentrate i n areas that s t i l l have some cover (V.W. Lehmann, pers. comm.). These d i f f i c u l t i e s must be considered when attempting to determine the population density of the area. Both problems could be overcome, but only at considerable expenditure of both time and money. Helicopter surveys i n four pastures on the King Ranch by K i e l (1963), i n 1962 and 1963, showed that peccary densities varied considerably between pastures (Table 28). The accuracy of the estimates of density that K i e l obtained was less than + 25°/o. 104. Table 28. Peccary density estimates on selected pastures on the Santa Gertrudis Division of the King Ranch determined from a helicopter survey by K i e l (1963). D e n s i t y (peccaries/sq mile) Pasture 1962b 1963° .. d Mean Mesquite 11 .4 38.8 17.6 Ebanito 5.1 8.0 6.2 Upper L i t t l e 6.3 6.3 North Canelo 5.5 8.7 6.7 a - accurate to less than±25°/o b - determined from 9 transects covering 3,240 acres c - determined from 5 transects covering 3,904 acres d - mean density i n peccaries/sq mile My s t r i p count estimates of peccary density i n the area of Mesquite Pasture showed a density that averaged 21.8 peccaries/sq. mile. Despite the fact that the mean estimates of density i n the a e r i a l and t e r r e s t r i a l censuses were quite s i m i l a r on Mesquite Pasture, the accuracy and s e n s i t i v i t y of the technique i s not adequate to permit comparison from year to year. Twenty miles NNE of the King Ranch i n habitat s i m i l a r to that on the King Ranch, E l l i s o r & Harwell (1969) counted a l l peccaries i n herds on t h e i r study area and determined the density to be 32 peccaries/sq. mile. Estimates of densities of peccaries i n west Texas indicate sparse populations i n both the Black Gap Area, 6.4 peccaries/sq. mile (L.S. Brownlee, Pers. Comm.) and the Wat-sbm' Ranch,v, 3.1 peccaries/sq. mile. The evidence provided by the home range data i s consistent with the density data. Populations l i v i n g i n habitats characterized by sparse vegetation and li m i t e d surface water may need to tr a v e l considerably more, and maintain a larger home range to maintain themselves than populations on less harsh areas. The south Texas results of home ranges of less than 3/4 sq mile are sim i l a r to those of Jennings and Harris (1953), and E l l i s o r and Harwell (1969). E l l i s o r and Harwell (1969) followed belled herds and found the home range to be about 311 acres i n t h e i r densely populated area 30 miles NW of .the Welder Refuge, and 548 acres i n t h e i r less densely populated area 20 miles NNW of the King Ranch. E l l i s o r and Harwell (1969) observed eight males making i n t e r -herd movements of distances up to 3 miles. In west Texas the home range i s considerably larger, upto 3 or 4 sq miles, concomitant with the lower density of vegetation and animals. 105. My results indicate larger home ranges than Jennings and Harris (1953) who indicate a l i n e a r range of 2 to 3 miles up and down draws. However, work cn Arizona peccaries, l i v i n g i n habitat s i m i l a r to the west Texas animals, (Neal, 1959b, Day 1968) has shown the range there" <to be about 1 1/2 sq. miles, considerably less than for the west Texas animals. There are no important differences i n the age-specific/sex r a t i o s of the south and west Texas populations (Table 5), nor between these and populations in Arizona studied by Sowls (1966) and Knipe (1958). The predominance of females i n the fo e t a l sex ratios that I found in the Texas populations has also been found i n Arizona peccaries and would thus appear to be. a feature of the species. The mechanism of the abrupt change i n sex ratios to favour males during the neonatal period i s unknown, but the predominance of males in the young age classes and the progressive change to predominance of females in the older age classes has been reported f o r many species. I did not determine what the causes of these d i f f e r e n t i a l mortality rates between sexes were. Analysis of population structure of peccaries i n south and west Texas populations showed that the population structure in south Texas was skewed considerably toward older animals compared with the west Texas population. Fifteen percent of the south Texas population was between 7-and 15-years old, whereas less than 7% of the west Texas population was 7—years or older. The oldest animal obtained in west Texas, was e s t i -mated at 9—years old. The differences appear to be associated with a s l i g h t l y higher mortality rate throughout l i f e i n west Texas populations (Tables 7 and 8). Although the slopes of the regressions f o r the two pop-ulations are not s i g n i f i c a n t l y different, data f o r the Black Gap Area are lim i t e d . Although the Black Gap Area was hunted and the Watson Ranch was not, the age structure of these two west Texas areas i s very s i m i l a r . Thus i t would appear that i t i s the harsher west Texas environment that has resulted in the s l i g h t l y higher mortality rate of animals there than i s present i n south Texas. There are several possible biases i n these data. In my personal collections I i n i t i a l l y t r i e d to c o l l e c t females only, but found i t im-pr a c t i c a l to continue. However, there i s s t i l l some bias present through the study. In the hunter k i l l e d animals, bias would probably be toward a bigger animal as discussed by Sowls (1961 a). Since there i s l i t t l e difference i n s i z e between sexes there should be l i t t l e bias towards either sex. 106. Another explanation f o r the higher proportion of females in the older age groups could be the fact that many old males take up a s o l i t a r y existence, and are not collected as frequently. However, s o l i t a r y animals are common to both the west and south Texas populations, hence, the same bias would be evident i n the two areas. There was no consistent difference i n sex rat i o s of animals conceived or born under different pr e c i p i t a t i o n conditions (Table 9). Changes i n the size and density of a population are obviously induced by changes i n reproduction and su r v i v a l . The production of young i s the result of the interaction of many interrelated environmental and physiological events, and i t may be readily affected by changes i n any of the events upon which i t depends. Proper understanding of reproduction in a species necessarily entails examination of the process in both sexes. In continually breeding species, as the peccary i s , the male i s presumed to be capable of f e r t i l i z i n g the female throughout the year. In peccaries there i s a br i e f period i n the hot dry part of summer when l i t t l e successful mating occurs (Jennings and Harris, 1953; Sowls, 1966,', th i s study). This suggested that either reduced l i b i d o , or short term s t e r i l i t y , i n the male might be involved. Analysis of weights and h i s t o l o g i c a l structures of the testes did not reveal any obvious change that could be associated with t h i s period. Weights and the t e s t i s index of a l l adult males collected did show some reduction i n size i n the winter (Fig. 15). Hi s t o l o g i c a l examination of testes of average and below average size indicated that the changes i n the tubule diameter or the percentage tubules i n t e r s t i t i u m and the number of sperm per tubule cross-section changed r e l a t i v e l y l i t t l e throughout the year (Fig. 17). However, there was no obvious change i n the testes during the hot part of the summer that could be equated with a decrease i n reproductivity a b i l i t y or l i b i d o . Fraser (1969) has pointed out that l i b i d o i s not just a function of androgen production i n the testes, but i s p r i n c i p a l l y under cerebral control. Van Tienhoven (1968), however, points out that admin-i s t r a t i o n of androgen to castrates restores the former sex drive. Because hormone production i s affected by decreased protein intake (van Tienhoven, 1968), i t i s possible that there i s a decrease i n l i b i d o i n peccaries-.as a result of the decrease i n proteinaceous forage in l a t e summer suggested previously. I t i s equally passible that hot weather i t s e l f could i n l a t e summer cause a decrease i n l i b i d o i n the male. 107. Comparison of the h i s t o l o g i c a l structures of a small sample of testes between the wet and drought periods showed that there was a s i g -n i f i c a n t difference only i n the amount of sperm present. . The number of sperm, although lower i n the dry period were s t i l l judged to be more than s u f f i c i e n t f o r successful f e r t i l i z a t i o n . Maturation of males i s l a t e r i n west Texas peccaries than i n both south Texas and pen-reared peccaries. Captive males are capable of f e r t i l i z i n g females at 10 1/2 to 11 1/2 months (Sowls, 1966; t h i s study) and south Texas peccaries possess large numbers of sperm i n the testes by 11 months. However, west Texas males did not have many sperm i n the testes u n t i l about 15 months. Testis size i n west Texas males show the same retarded growth (Tables 13 and 15). Because of the lower condition levels of the west Texas peccaries, these differences are to be expected. Limited evidence suggests that t e s t i c u l a r growth and maturation age depend upon the time of year, as well as upon the c l i m a t i c , hence vegetation, conditions during which the young animal approaches maturation. A 3-month old male (P-52) collected i n November, 1965, had a TI of 0.16, whereas twin males (P-104, and P-105) 3 1/2 months^.old, collected i n July, 1966, had t e s t i s indices of Q.,34 and 0^4. . Both of these were during the above average r a i n f a l l period, but food conditions i n the f a l l are not as favourable as in the spring. Further evidence of the effect of condition i s provided by three pen—reared Welder 3.7—month old peccaries. The twins (Pc159 and Pc160) who were the same age, but one t h i r d the carcass weight of the single (Pc 158), both had TI of 0.32, whereas the single had a TI of 0.55. The twins were raised by a sow that lactated poorly, and the single was s t i l l nursing when k i l l e d . Sperm production i s also affected by condition, as shown by two males about 9 1/2 months old. P-70, collected i n March 1966 following a favorable winter, had a kidney f a t index of 1/4; P-128, collected i n A p r i l , 1967 after 8 months of drought had a kidney f a t index of 1/8. P-70 had an average of 9.2 sperm per tubule cross—section, whereas P—128 had an average of 0.2 per tubule cross-section. Older animals show v a r i a b i l i t y , nevertheless the interpretation i s consistent with results quoted by Sadleir (1969) and Fraser (1969). S e n i l i t y i s another factor which might influence reproductive rate and productivity, p a r t i c u l a r l y in populations with a high proportion of old animals. The oldest males collected were 14, 13.8, and 12 years old (estimated from dental annulations). A l l of these had t e s t i s indices above 108. 2.0, and the 14 and 12 year olds had p l e n t i f u l supplies of sperm i n the tubules. The 12-year old (P-5) had an abnormally large l e f t and poorly developed right t e s t i s . No sperm were observed i n the vasa efferentia of the l e f t t e s t i s despite i t s having the highest average sperm count 155 per tubule cross-section with up to 244 sperm i n one cross-section. The 14-year old (P-86) had 76 sperm per tubule cross-section, only s l i g h t l y less than the o v e r a l l average of 91. A 9.2 year old west Texas male (\IVT-1), a r e l a t i v e l y old male i n view of the younger population i n west Texas, had a low sperm count of only 40. The proportion of i n t e r s t i t i a l tissue i n P-86 and WT-1 was s l i g h t l y lower than average. Hence a decrease i n androgen and perhaps l i b i d o might be expected. Parkes (1966) found a great deal of i n t e r s t i t i a l tissue i n the t e s t i s of an old 100-pound captive collared peccary. Judging from the weight, the animal was extremely f a t , and the resulting increased i n t e r s t i t i a l tissue lends support to my hypothesis that condition influences t e s t i s histology. The role that older males take i n breeding i s not known, but the fact that many older boars seem to take up s o l i t a r y existence suggests that they do not play an important part in. reproduction even though there i s no evidence of s i g n i f i c a n t decline i n the number of spermatozoa demonstrated i n the tubules. Although appreciation of the male role i s necessary, reproduction i n the female i s more s t r i k i n g l y responsive to changes i n habitat. I t has already been shown that body condition i s responsive to changes i n climatic and range conditions. In t h i s study I have examined the response of re-productive pattern i n the female to different climatic conditions on one habitat and to a lesser extent.between a mesic and an a r i d habitat. I have attempted to analyse reproduction i n the f i e l d through examination of re-productive t r a c t s , p a r t i c u l a r l y the ovary, of wild peccaries. The ovary can provide-.much additional information on reproductive patterns and rates (Cheatum, 1949; Golley, 1957; Thomas, 1970) and i n effect serves to increase the amount of data derived from the r e l a t i v e l y small sample of reproductive tracts available. The analysis of reproduction i n wild peccaries i s compared with reproduction i n the pen-reared peccaries with known reproductive history. The gross morphology of the reproductive t r a c t described e a r l i e r i s substantially the same as Wislocki's (1931) description. The remarkable feature i s the short Fallopian tubes which are approximately the same length i n both v i r g i n and pregnant animals. 109. Sowls (1966) description of the mammae in Arizona peccaries applies also to the Texas subspecies. Wislocki's (1931) and Jennings and Harris's (1953) descriptions of the mammae are correct for functional mammae but they apparently did not observe the v e s t i g i a l two pectoral pair of mammae. My interpretation of the ovarian structures d i f f e r s from Wislocki's (1931) description of the ovary i n a pregnant sow only on interpretation of his "degenerate corpus luteum". I t i s necessary to.examine early development of the ovary i n order to understand the presence of thi s 'degenerate corpus', which i s actually an unusual retention of a secretory medullary body. According to Burns (1961:102), i n normal mammalian sex d i f f e r -entiation, the i n d i f f e r e n t gonad i s formed from the genital ridge and has a medullary portion and a germinal e p i t h e l i a l layer. During the primary p r o l i f e r a t i o n , the germinal epithelium produces primary (or medullary) sex cords which 'bud' into the medullary area. At t h i s stage, the medullary region represents the male component, and the germinal epithelium represent the potential cortex or female portion. At t h i s early stage, the male sex. cords connect to the rete cords (the mesonephric connecting tubules) which juxtapose the glomerular capsule of the embryonic kidney. I f the sex of the foetus i s male, the primary sex cords develop, and the germinal epithelium i s reduced to a thin membrane. The tunica albuginea develops, subadjacent to the v e s t i g i a l germinal epithelium and the rete cords became the rete t e s t i s connecting the seminiferous tubules (primary sex cords) to the vasa efferentia. I f the sex i s female, a second p r o l i f e r a t i o n by the germinal epithelium produces the secondary (or c o r t i c a l ) sex cords which surround the medullary portion. The male sex cords are reduced, and they and the rudimentary tunica albuginea gradually disappear. The c o r t i c a l cords go on to form the cortex, and subsequent p r o l i f e r a t i o n from the peripheral germinal epithelium produces the primordial f o l l i c l e s . The medullary region becomes i n d i s t i n c t through regression and dispersion of the cord c e l l s , and invasion by the c o r t i c a l c e l l s . However, Gropp and Ohno (1966) have proposed a different concept of gonadal d i f f e r e n t i a t i o n i n c a t t l e and conclude that f o l l i c u l a r c e l l s of the ovary and i n t e r s t i t i a l c e l l s of the testes are homologous (van Tienhoven, 1968). 110. They consider that the function of the germinal epithelium i s minimal, and that secondary sex cords are not observed. In the male, the semi-niferous tubules enlarge from ' f o c i ' i n the deeper areas of the blastema, and engulf germ c e l l s which have migrated into the area. In the female the outer c e l l layers of the blastema arrange themselves into f o l l i c u l a r cords and develop outwards to make contact with, and engulf, the peripheral layer of immigrating oogonia to become avigerous cords. Development of the peccary ovary i s unusual i n the retention of the tunic-surrounded medulla throughout l i f e . Leach and Conaway (1963) working on the striped skunk found that the ovarian medulla persists with primary sex cords present u n t i l about 11 weeks post-partum when i t degen-erates to a mass of i n t e r s t i t i a l tissue. P r i o r to that time, the cortex shows very l i t t l e development and i t i s not u n t i l the medulla degenerates that the cortex develops. Deansly (1966), working on the mole, describes a structure in,, the mole ovary which i s s i m i l a r to that found i n the peccary. This she terms the medullary part, and she has found that the structure enlarges and regresses with the end and beginning of the mating period. H i s t o l o g i c a l analysis of the peccary ovaries revealed that females in south Texas have started to form corpora lutea of oestrus around 8 months. These probably coincide with " s i l e n t " heats as laboratory animals did not mate u n t i l about 11 months. Sowls (1966) however, raised one female that mated at 8 months. No wild peccaries were found pregnant u n t i l after they were 16 months old, and most appear to become pregnant i n the l a s t half of t h e i r second year. Although there was l i t t l e difference between west and south Texas peccaries i n age at f i r s t pregnancy (largely due to small sample size and time of c o l l e c t i o n of the west Texas specimens) there was some evidence of delay, of maturity during the drought period in south Texas. The only two females that had reached 2 years old without becoming pregnant were collected i n March, 1967 (drought period) after the peak mating period. They had not been pregnant and they did not show any ovarian indication of recent ovulations. Maximum ovulation and implantation rates were not reached u n t i l about 5 years (Table 23). This coincides with the age at which maximum siz e of the animal i s reached (Fig. 10). I t appears that the animal can then channel most of i t s energy into reproduction rather than having to • divert some to growth (Maynard and L o o s l i , 1962) . 111. Sowl's (1966) information on penned peccaries indicates they are polyoestral and have an oestrous cycle l a s t i n g 22.6 to 24.6 days and duration of oestrous averaging 3.5 to 4.8 days. Our less intensive examination of the oestrous cycle in penned animals showed si m i l a r results with wide var i a t i o n . Behavioural data obtained on pen-reared peccaries at U.B.C. are consistent, though conception was generally a l i t t l e l a t e r (Table 21). Age of maturation appears to be controlled by the condition of the range and season. The limited data suggest that i f the female i s over 12 to 15 months old during the major winter breeding season, she probably becomes pregnant. However, i f she was born i n the f a l l , then she w i l l probably not mature u n t i l the winter when she .is about 18 months old. Poor range conditions apparently can retard the age of maturation by at least 6 months. Sowls (1961b, 1966) found the gestation period f o r peccaries to range' from 141 to 150 days with a mean (maximum) of 145.8 days. The range Sowls (1966:161) shows i s a result of a miscalculation. The data derived from t h i s study agree rather closely with Sowls data. Hafez (1964) found that some domestic animals tend to have s l i g h t l y longer gestation periods i f the gestation period i s primarily during the winter. /There i s a tendency to t h i s in the captive animals raised at U.B.C. although the difference i s not s i g n i f i c a n t . The mean of s i x gestation periods where the young were born between January and A p r i l , i s 144.5 days (+ 0.5 S.E). The mean of seven gestation periods resulting i n June to October births averaged 142.8 days ('+ 0.9 S.E). There was also a tendency for l i t t e r s of one to have a shorter gestation and l i t t e r s of three to have a longer gestation period, although the differences are not s i g n i f i c a n t . This range in length of gestation period t h e o r e t i c a l l y permits the birth of two l i t t e r s per year to each sow. Breeding takes place throughout the year, but i s concentrated in two peaks. Backdating to conception date of foetuses, using the formula of Hugget and Widdas (1951) and growth curves of Ullrey, et a l . , (1965) and Thomas (1970), and observations of young in the f i e l d , revealed a major breeding season between December and February and a minor peak in A p r i l or May in south Texas peccaries. The ultimate selective pressure on timing of the breeding season i s probably through survival of young during the vegetative growing seasons of la t e s p r i n g — e a r l y summer, and the f a l l . 112. The exact time of the peak of breeding appears to be influenced by several factors. R a i n f a l l seems to be the most important factor. I t acts i n d i r e c t l y through range conditions resulting from previous seasonal r a i n f a l l and more d i r e c t l y through the presence of green plants containing high protein and perhaps estrogen l e v e l s . Sadleir (1969') and Samuel (1967) have reviewed, respectively, the effects of protein - - r i c h diets causing "flushing", and the effect of estrogen-like compounds on reproduction. The situation i s probably s i m i l a r i n west Texas, but data are not adequate to show the pattern over the whole period. On the Black Gap area i n 1966 spring rains supplemented by heavy rains i n August, September and October, resulted i n r e l a t i v e l y high production of young i n the l a t e f a l l . On the Watson Ranch, the part u r i t i o n peak i n 1966 was i n May and June, following November and February rains. The situation i n west Texas appears s i m i l a r to that described by Sowls (1966, 1961a) i n Arizona. Thus peccaries have what might be termed an obligatory reproductive period i n the winter and spring, and are f a c u l t a t i v e breeders throughout the remainder of the year. The winter breeding period appears to be keyed to a p a r t u r i t i o n period coinciding, in general, with the r e l a t i v e food abundances of the spring and summer vegetation growing period. As Sowls (1966) has suggested for Arizona peccaries, survival of the young would be the ultimate selective factor co n t r o l l i n g the winter breeding period. This same control has been proposed for the Sonoran white-tailed deer (McCabe and Leopold, 1951). In addition, precipitation-controlled range conditions might be regarded as the proximate factor controlling exactly when, during the winter, the animals do breed, and whether they can take advantage of a second breeding season i n l a t e spring or. early summer. I t appears that the breeding season i n the peccary i s . b a s i c a l l y the continual optimal season type of Sadlier (1969), but at the north edge of the range in Texas i t has adapted to a fixed, but i r r e g u l a r , optimal season for production of young. Since the optimal season i s usually very long i n south Texas, from March to November, peccaries take advantage of i t by producing one l i t t e r of young early i n the optimal period, and another l i t t e r during the l a s t t h i r d of the optimal period. This would combine Sadleir's (1961:51) Type 4 and 5 breeding patterns concerning length of time from conception to weaning i n r e l a t i o n to the optimal season. As Sadleir suggests, there might be a higher rate of mortality of the l a s t l i t t e r s as a res u l t of the unpredictability of the end of the optimal period. Reinforcement of l a t e breeders would be i r r e g u l a r i n t h i s case. 113. As a result of more intense seasonal changes and a more re-s t r i c t e d favourable breeding season, the reproductive period i n west Texas i s shorter. However, i n years with good range conditions, breeding probably extends over the major part of the year also. A measure of the stress on a population can be determined by comparing productivity of the studied population with some known standard. The present comparison of productivity i n a south Texas population during a drought and a moist year, with more limited data on productivity i n a west Texas population during a semi-drought and a moist year revealed im-portant differences from the productivity of pen-reared animals. Productivity can be determined at several points i n the l i f e cycle: ovulation incidence, conception rate, implantation rate, f o e t a l counts, pa r t u r i t i o n rates, and juvenile counts. I have determined the ovulation incidence (from corpora lutea or CL-P scars), gross productivity (from fo e t a l counts), and net productivity (from r a t i o s of juveniles to adults). Ovulation incidence provides the potential number of young the sow, or population, could produce under existing conditions. Gross productivity (commonly r e s t r i c t e d to the b i r t h rate) provides an estimate of embryonic mortality, and net productivity (the recruitment to adult populations) provides an estimate of post—natal mortality. Peccaries are capable of reproducing twice a year. Therefore, i t i s necessary to separate ovulation and implantation,incidence, that i s , the number of ova shed and the number of embryos implanted per pregnancy, from the ovulation and implantation rates, that i s , the number of ova shed and the number of embryos implanted per year. The ovulation rate i s d i f f i c u l t to determine i n wild peccaries because i t necessitates determining the number of scars of pregnancy formed in the ovary either during a year, or during the l i f e t i m e of the animal. I did not think that my counts of scars of pregnancy were accurate enough to determine the rate of implantation during the animal's l i f e t i m e f o r some of the ovaries, p a r t i c u l a r l y those with large corpora lutea. However, i n pregnant animals i n which the l a s t previous CL-P was s t i l l regressing, I could say with reasonable certaintyithat the animal had conceived twice in that year. The period actually covered i s somewhat less than 10 months, since the corpora regress quite rapidly and by 5 months reach a size at which they are d i f f i c u l t to distinguish from e a r l i e r scars of pregnancy (Fig. 20). Thus, with the f i v e months gestation p r i o r to i n i t i a t i o n of degeneration, a period of about 10 months i s obtained over which frequency of pregnancy can be determined. 114. Since peccaries i n west Texas were i n poorer condition than south Texas peccaries, and those under drought conditions were i n poorer condition than those under good range conditions, i t i s peculiar that there i s no difference i n ovulation rates. However, Hart and M i l l e r (1937) found ovulation rates were not affected during short term n u t r i t i o n a l deficiencies. Because the drought during the study i n south Texas lasted for only 13 months, i t i s l i k e l y the ovulation incidence had not been seriously affected i n that time. I t i s more d i f f i c u l t to explain the lack of s i g n i f i c a n t difference i n ovulation incidence between the west and south Texas populations. However, i t i s reasonable to expect that the decrease I have shown in the implantation incidence during times of food stress i s r e a l . This has been shown for a number of mammals (Sadleir, 1969). How often a sow becomes pregnant has important implications in productivity. Domestic pigs have been shown to have an anovulatory post-partum oestrus and are generally anoestrous during l a c t a t i o n (Asdell, 1964), but come into oestrus shortly after young are removed (Nalbandov, 1964). Several other species have oestrous cycles while l a c t a t i n g (Perry and Rowlands 1962:299). Sowls (1966) found that peccaries have a post-partum oestrus 8'or more days after p a r t u r i t i o n that on one occasion was f e r t i l e . He also found that sows become pregnant while l a c t a t i n g . I have confirmed tKiis and found that captive peccaries frequently have a f e r t i l e oestrus 5 to 12 days after p a r t u r i t i o n . With the f e r t i l e oestrus coming 5 to 12 days after p a r t u r i t i o n , i t i s possible for peccaries to have a l i t t e r every 5 months. Sow UBC 4 came close to r e a l i z i n g t h i s potential (Table 19). She produced seven l i t t e r s over a 3 1/4 year period, an average of 5.7 months per l i t t e r . A l l of her l i t t e r s were allowed to remain with her for 2 to 3 months following p a r t u r i t i o n . With t h i s high potential reproductive rate, comparison of per-formance of f i e l d populations was of interest. Animal condition, as a result of previous range conditions, has a strong influence on reproductive a c t i v i t y and gross productivity. The number of sows ovulating and conceiving, and the ovulation and implantation rates a l l r e f l e c t the condition of the animal and the range upon which i t feeds. In 1965 and 1966, i n south Texas, productivity was high (301 foetuses/ 115. 100 adult sows i n 1966) as a result of a high prevalence of pregnancy (71%) and rebreeding shortly after the f i r s t p a r t u r i t i o n (41%) . In the drought period there were only 118 foetuses/100 adult sows because of a low pregnancy rate (26%) and very few consecutive pregnancies (9%). Data on productivity of west Texas animals are meagre; however, the range condition-productivity relationship appears to be maintained. In 1965, a dry year, productivity was low with l i t t l e l a t e season production of young, whereas i n 1966, a r e l a t i v e l y moist year, there was considerable production of young i n the l a t e spring, the l a t e season production of young was high. Thus, i t would appear that peccaries are able to take advantage of th e i r high reproductive potential during favourable f i e l d conditions. During dry f i e l d conditions, however, not only do conceptions decrease, but also the oestrus cycle may be suspended. Net productivity also changed with range condition and condition of the sow. During periods of good range conditions, twins were common and t r i p l e t s occasional, and survival during the neonatal period was r e l a t i v e l y good. I t appears that at no time i s neonatal survival very high. Even pen-born l i t t e r s l o s t 25% of the young within two days of b i r t h . Sowls (pers. comm.) however, found that survival of pen-born l i t t e r s was very high. When range conditions were poor, the proportions of singles increased, and although twins remained common i n utero, usually no more than one of the twins survived the neonatal period. The cause of death of neonatants i s largely unknown, but i n pen-reared peccaries, young that died weighed much less than those that survived. Studies of the effects of plane of nu t r i t i o n of the female during the l a s t half of pregnancy and lac t a t i o n have shown reduced weight and survival of young on low-plane diets (Thomson and Thomson, 1949, 1953; Pomeroy, 1960; Verme, 1962, 1965; Murphy and Coates, 1966; Sowls, 1966). I t i s l i k e l y that the response i s s i m i l a r in wild peccaries since there i s such a high mortality of neonatants and neonatant mortality i s probably the major s i t e of population "control" of peccaries on a r i d land ranges. L i t t e r s ize frequency i n wild Arizona peccaries (Sowls, 1966) d i f f e r s considerably from that i n south Texas (P<.1) (Table 22). A higher proportion of the sows there produce t r i p l e t s . This did not hold true i n comparison of pen-born l i t t e r s (P = .5). Wild Arizona peccaries produced t r i p l e t s 33% of the time, although i n 48% of the cases, one of the t r i p l e t s was dead i n utero. This i s curious i n view of the lower n u t r i t i o n a l status of wild animals, and i s probably best explained by the 116. sample s i z e . Factors affecting adult and juvenile mortality are probably of l i t t l e consequence except during times of n u t r i t i o n a l stress. Predation,_ parasites, and diseases appear to be of minor importance (Appendix G). However, inclement weather, i n combination with low quality, bulky food seems to take a high t o l l of a l l age classes (Appendix G) . In two herds, 29°/o of the animals died or disappeared during the cold period accompanying the drought of 1966-67. At the same time the Welder Refuge deer herd decreased by about 32% (Low, 1967, unpublished report). Hunting can be an important factor in vulnerable, isolated herds, but i s largely unassessed i n terms of effects on whole populations. Sowls (1961a) suggested that the proportion of 11-to 21 1/2-month old peccaries k i l l e d i n the annual hunt in Arizona ranged from 9 to 20% and was dependent on the p r e c i p i t a t i o n l e v e l f o r the period before they were bOrn. The results of t h i s study agree with his findings. A model of factors affecting peccary populations i s shown i n Fig. 24. Elimate, primarily p r e c i p i t a t i o n but also temperature, i s probably the ultimate control of population density, acting mainly through food supply. The mechanism of density "control" appears to be through food-related changes i n productivity, neonatal mortality, and winter mortality of juveniles and adults. Productivity i s controlled primarily through im-plantation success, and prevalence and frequency of pregnancy. Since peccaries are capable of very high reproductive rates (two l i t t e r s annually of two to three foetuses per l i t t e r ) under ideal conditions,., the population can quickly take advantage of periods of good range conditions. However, severe food quality r e s t r i c t i o n s may cause pregnancy rates to drop below the population maintainance l e v e l . There have been few studies of reproductive ef f i c i e n c y and population maintainance i n the larger herbivores l i v i n g under desert or semi-desert conditions. Research on the red kangaroo (Newsome, 1966b, et. a l . , 1967) euro (Ealey and Main, 1967) and on the white-tailed deer in Texas (White, 1966).have revealed that drought conditions i n a r i d and semi-arid environments act upon populations of larger herbivores f i r s t by r e s t r i c t i n g reproduction, and l a t e r by direct mortality of a l l age classes as a consequence of food shortage caused by water shortage. I have shown that the peccary i n Texas s i m i l a r l y responds to changes i n a r i d i t y by changes i n i t s reproductive success. There i s also some evidence that suggests that when r a i n f a l l i s below 70% of the mean, the death rate of adults r i s e s . BEHAVIOR RMGE MANAGEMENT 'Brush c l e a r i n g Water management — ~~~\ CLIMATE Temperature R a i n f a l l H u m i d i t y VEGETATION Cover Food \ GEOLOGY Topography S o i l s REPRODUCTION O v u l a t i o n r a t e I m p l a n t a t i o n r a t e O e s t r u s f r e u q i t e n c y G e s t a t i o n f r e q u e n c y MORTALI TY N e o n a t a l l o s s R e c r u i t m e n t f a i l u r e A d u l t d e a t h POPULATION DENSITY MORTALITY FACTORS P r e d a t o r s P a r a s i t e s and d i s e a s e H u n t i n g P o o r n u t r i t i o n - C o l d weather C a t a s t r o p h i e s -H u r r i c a n e , f l o o d Figure<^2itZ3 F a c t o r s a f f e c t i n g p e c c a r y d e n s i t y . • major c o n t r o l •> minor o r p o t e n t i a l i n f l u e n c e 118. In a r i d lands the balance between years of drought and years of s u f f i c i e n t r a i n f a l l fluctuates so i r r e g u l a r l y and frequently that this alone governs the density that these animals reach (Fig. 25). There i s no evidence that mechanisms covering population size i n the peccary populations are density dependent. Seldom, i f ever, does density reach a point where t r a d i t i o n a l i n t r i n s i c density dependent forces operate. In Texas the evidence available points to this conclusion as applicable during the period of this study. SUFFICIENT PRECIPITATION DROUGHT SUFFICIENT PRECIPITATION DROUGHT • J J J J J J J vl J J J . E n v i r o n m e n t a l r e s i s t a n c e t o p o p u l a t i o n d e n s i t y J J i q I i \ J j J J J I J J if* / 7* <? H i g h r e p r o d u c t i v e r a t e and s u r v i v a l Low r e p r o d u c -t i v e r a t e & s u r v i v a l • cu-•or : ej. •©•• •u-.o: •a-•r-r H i g h r e p r o d u c t i v e r a t e and s u r v i v a l Low r e p r o -d u c t i v e r a t e & s u r v i v a l H i g h q u a l i t y f o o d M o del of p r o c e s s o f p o p u l a t i o n change i n South Texas p e c c a r y p o p u l a t i o n s . 120. 6. APPENDICES. 121 . Appendix A. S c i e n t i f i c names cf p i Nomenclature follows Jones, plants, Peterson (1963) for for the mammals. Agarito Anacua Ayenia, dwarf Blackbrush Bristlegrass, plains sandhill southwestern Buffalograss Catclaw Chinograss Chittimwood Colubrina, Texas Creosote bush Croton Croton, one—seed Goldeneye Granjueno G u a j i l l o Hackberry, netleaf sugar Hairy tubetongue Huisache Iceweed Junipers Lechuguilla Lotebush Lupine Mesquite, creeping honey •ak, l i v e Texas • c o t i l l o ts and animals cited in the text. a l . ( l 9 6 l ) and Gould (1962) for the e birds, and H a l l and Kelson (1963) Berberis t r i f o l i o l a t a  Ehretia anacua  Ayenia p u s i l l a Acacia r i g i d u l a  Setaria leucopila S. firmula S. scheelei  Buchloe dactyloides Acacia greggii  Bouteloua breviseta  Bumelia lanuginosa  Colubrina texensis  Larrea divaricata Croton texensis, C. capitatus, C. neo-mexicanus  Croton monanthogynus Viguiera stenoloba  C e l t i s p a l l i d a  Acacia berlandieri C e l t i s r e t i c u l a t a C. laevigata  Siphonoglossa p i l o s e l l a  Acacia farnesiana Verbesina microptera Juniperus spp. Agave lec h e g u i l l a  Condalia o b t u s i f o l i a  Lupinus havardii Prosopis reptans P. glandulosa Quercus virginiana Q. texana Fouquieria splendens Parthenium, l y r e - l e a f P r i c k l y ash Pr i c k l y pear cactus Parthenium confertum  Zanthoxylum fagara Opuntia lindheimeri, 0. engelmannii 122. Sand bur Sapote Sotol• Spiny aster Tarbush T a s a j i l l o Twisted acacia Cenchrus incertus, C. myosuroides  Bumelia c e l a s t r i n a  Dasylirion texanum, D. ieiophyllum  Aster spinulosus Flourensia cernua  •ptunia leptocaulis Acacia tortuosa Whitehorn Yucca Acacia constricta Yucca elata, Y. thompsoniana, Y. torrey Y. rostrata Birds Bobwhite Colinus virginianus Turkey, Rio Grande Meleagris galopavo intermedia Mammals Antelope Badger Bobcat Cotton rat Cottontail Coyote Deer, mule white-tailed Sonora white—tailed Gray fox Jackrabbit Mountain l i o n Pig, f e r a l Racoon Woodrat, southern plains Antilocapra americana  Taxidea taxus  Lynx rufus  Sigmodon hispidus S i l v i l a g u s floridanus, S. auduboni  Canis latrans •docoileus hemionus crooki 0. virginianus texanus •. v. couesii Urocyon cinereoargenteus Lepus c a l i f o r n i c u s F e l i s concolor Sus scrofa Procyon l o t o r Neotoma micropus 123. Appendix B. Handling trapped and captive peccaries. The canine tusks of peccaries are capable of i n f l i c t i n g severe wounds. Therefore i t was necessary to subdue the animals before marking and measuring were done. The i n i t i a l and most successful method of subduing trapped peccaries was to noose them through a hole i n the top of the trap. A 1/8 inch wire cable was f i t t e d to l i g h t 6-foot conduit pipe so that a noose was formed at one end. The noose was placed around the animal's-neck and pulled taut. After a short struggle the animal became quiet from apnea. I t was then quickly removed from the trap, i t s legs t i e d , and i t s snout strapped to prevent use of i t s dangerous canine tusks. The animal could then be safely handled. I experimented with several immobilizing and t r a n q u i l i z i n g drugs that would permit e f f i c i e n t handling of the animals. Pen—reared animals were readily tranquilized with Tranimal or a l powder (Hoffman-LaRoche). This i s a wide tolerance t r a n q u i l i z e r and was mixed with the pelleted food and given to the animals several hours before handling. The effective dose i s shown i n Table 1. The t r a n q u i l i z i n g effect lasted up to 36 hours. During that time, the animal could s t i l l walk, but had l i t t l e coordination and could be handled readily. When i t was necessary to anaesthetize the animals completely f o r tooth impressions, I put a p l a s t i c bag, containing a chloroformed swab, over the tranquilized peccary's head u n t i l the animal succumbed. By judicious use of the chloroform swab, I could keep the animal immobile f o r at least an hour with no apparent a f t e r - e f f e c t s . I used Tranimal mixed with the pelleted cotton-seed cake bait i n the traps, sodium pentobarbital administered by a hand-syringe to trapped peccaries, and succinylcholine chloride' i n Cap-chur gun darts on free-ranging peccaries. The successful dosages are l i s t e d i n Table 1. Use of drugs on trapped peccaries was discontinued because 1) of the necessity of catching the animal before i n j e c t i n g the drug (the small target area made use of Cap-chur darts dangerous to the animals), 2) the long recovery time unduly exposed the animals to heat prostration i n t h e i r insensible wanderings and to possible predation. Physical r e s t r a i n t of the animals proved to be most e f f i c i e n t . 124. Table 1 . Tranquilizing and immobilizing drugs and successful dosages used on penned and trapped peccaries. time to (min) Dosage effect |recovery Remarks Tranimal (Hoffman-LaRoche) - ora l powder 20.6 mg/lb 39.6 mg/lb 1 .5 gm/gal. food 2.5 gm/gal. food l . t 90 150 90 60 Sodium Pentabarbital (Winthrop Lab 8 hrs, 36 hrs. 36 hrs. N.Y.) -Considerable loss of co-ordination L i t t l e coordination Slight t r a n q u i l i z a t i o n Marked t r a n q u i l i z a t i o n , loss of coordination 10.5 mg/lb 1 .5 25 Anaesthetized 11 .3 mg/lb l . t 60 g.t. 120 Anaesthetized 13.1 mg/lb 1 .5 145 Anaesthetized 14.1 mg/lb 1 .5 g.t. 120 Anaesthetized Succinylcholine chloride (Sucostrin) - intramuscularly 0.26 mg/lb 0.4 mg/lb 5 3 60 died Retained jaw movement Dart broke r i b , s p l i t d i a -phragm, punctured i n t e s t i n discharged in lung 125. Appendix C. Age determination of peccaries. 1 . Young and Adults. Since age i s important i n reproduction, I desired to determine the age of the animals as accurately as possible. Several age determination techniques have been developed that have a p p l i c a b i l i t y to one or more species, but only tooth patterns and eye lenses have been previously assessed for age determination of peccaries (Sowls, 1961a; Kirkpatrick and Sowls, 1962; L. K. Sowls, pers. comm.). In my study I tested the usefulness of eye lens weights, tooth eruption pattern, tooth wear, and annulations in the dental cementum as indices of age. In addition, data on ide a l weights and body measurements during early l i f e stages were obtained from captive-born and reared animals. These growth data are mainly useful for determining growth rates under good conditions. The data can then be used as a basis f o r determining the n u t r i t i o n a l adequacy of the wild diet. These data have been treated separately, even though they have been used to determine the approximate ages of free-ranging and live-trapped animals. The other three methods w i l l be treated f u l l y here. 1.1. Methods Eye lens weights have been successfully used i n the determination of age of a variety of smaller mammals and the young stages of some larger mammals. Friend (1967 a, b, c,) has reviewed the c r i t i c a l methods of pre-paration of lens material and the species on which i t has been successfully used. The method used i n my study was s i m i l a r to that of Lord (1959, 1963). The eyes were removed from the s k u l l and the l e f t lens and the right eyeball, which was s l i t to f a c i l i t a t e f i x a t i o n , were put i n a v i a l of 10% Formalin and l e f t for periods varying from two weeks to 12 months. P e r i o d i c a l l y the lenses which had accumulated were removed from formalin', placed in indi v i d u a l v i a l s and dried at approximately 80°C for 14 days. When dry, the lenses were removed from the v i a l s and weighed to the nearest 0.1 mg. The weights f o r l e f t and ri g h t lenses were recorded separately. Damaged lenses were discarded. I p e r i o d i c a l l y noted tooth progression i n pen-reared animals of known age to establish the eruption pattern f o r the Texas collared peccary. Tooth impressions were taken on some pen—reared animals (Flyger, 1958). Since captive peccaries were fed pelleted feeds and wear on the teeth i s greatly affected by the type of food consumed, I did not emphasize examina-tion of tooth wear i n the captive animals. 126. The age of some live-trapped young, and a l l those collected, was determined by comparing tooth patterns with known-age patterns. The age of collected animals over 24 months (completion of the eruption of permanent teeth) was determined by tooth wear c r i t e r i a established by Sowls (1961 a: 499). These c r i t e r i a are: s l i g h t wear - - Class 1; wear conspicuous on Molars 1 and 2 — — Class 2; a l l teeth showing wear — — Class 3; very heavy wear on a l l teeth - - Class 4; and extreme wear with some teeth missing - -Class 5. A l l of the s k u l l s from the peccaries collected i n Texas were placed i n a progressive series and the l i m i t s of each of the wear classes decided. Annulations i n dental structures have received considerable at-tention i n the l a s t few years as an aid i n determining the age of large mammals. Madsen (1967) and Sergeant (1967) have reviewed the l i t e r a t u r e . Low and Cowan (1963) hypothesized that annulations i n mule dder teeth were caused by both rutt i n g and food shortage. Since peccaries under-go i r r e g u l a r food shortages that vary seasonally and annually, and breed throughout the year, there was some question about adapting the method tp peccaries. When the teeth were examined, however, annulations were obvious in the cementum of some animals, although d i f f i c u l t to interpret in others. I assessed the method using teeth from animals pen-reared i n Arizona by Dr. Sowls, and i n Texas and at U.B.C. during t h i s study. The f i r s t i n c i s o r was used f o r examination of dental cementum annulations because i t i s easily extracted and i s the f i r s t of the replace-ment dentition to erupt. Several canines were sectioned but these proved of no additional value, and were considerably more d i f f i c u l t to prepare f o r examination. The tooth preparation procedure was modified only s l i g h t l y from Low and Cowan (1963) by using 30°/o formic acid with 10% formalin added, to decalcify the teeth. Transverse sections were cut at 8 JJ with a rotary microtome; every twentieth section was taken from the lower l/5th of the root and mounted on a glass s l i d e . Special attention was paid to obtaining sections from the area where the dentine f i r s t appears when the tooth i s sectioned from the apex of the root. I t i s usually here that the cementum i s thickest. The sections were stained with Harris Haematoxylin and mounted. The sections were examined with a microscope using transmitted l i g h t . A blue-green f i l t e r enhanced the v i s i b i l i t y of annuli i n some sec-tions. Plate 1a shows the method of counting annulations. The method i s 127. explained more f u l l y in the following discussion. Accuracy of the counts was improved by referring to other indicators of age, such as tooth wear class and closure of the canine root, i n order to establish the approximate order of magnitude of the number of annulations to be counted. Canine teeth were examined for external cementum annulations (Scheffer, 1950), closure of root canal, and length of exposed tusk. 1.2. Results and Discussion. The lens weights of 157 animals (including 24 known-age animals from one day to 54 months old) were determined. The average difference i n weight between the l e f t and right lenses was 3.5 mg., a difference of 0.9% from the mean lens weight, and t h i s was not s i g n i f i c a n t . There was no si g n i f i c a n t difference between weights of lenses from males and females. Figures 1a and b show the lens weights grouped by annulation-eruption age and by age classes. There was a s i g n i f i c a n t difference i n lens weight between only Age Class 1 and the remainder, and between 1 year olds and those older. Fig. 2 shows the lens weight-age relationship of animals up to 21'.months of age. After that age the rate of weight increment be-came so low that ind i v i d u a l variation masked the weight gain. The regression l i n e of lens weight on age for the known-age animals up to 21 months was y = 0.14x - 6.0 (y = age i n months, x = lens weight) with a highly s i g n i f i c a n t correlation c o e f f i c i e n t (r = .98). The regression of lens weight on tooth eruption age of a l l of the young animals less than 24 months collected was y = 0.13x - 6.5 with a highly s i g n i f i c a n t correlation c o e f f i c i e n t (r = .95). The curve f o r lens weights of known—age animals l e v e l l e d o f f by age 24 months (Fig. 2) to a slope that made the regression unreliable beyond t h i s age for age prediction, even though lens weight continued to increase (Fig; 1). However, because of the l i n e a r relationship i n the younger animals, the technique appears v a l i d f o r age prediction before that age. Fig. 1a shows a s i g n i f i c a n t difference (P<^ .05) between lens weights of animals 1 year old, 2 years old, and greater than 2 years old. When a l l of the animals older than seven years were'grouped there was a s i g n i f i c a n t d i f -ference (P<.05) between them and younger animals (Fig. 1b). A larger sample might show significance between age class 2 and 3 and the remainder, but not l i k e l y between classes 4 and 5 because of the high v a r i a b i l i t y i n 128. Figure 1. Lens weight d i s t r i b u t i o n by A) age class and B) annulation age of south Texas peccaries. Values shown are: mean, stan error at the t _ l e v e l , and the range. '.129. LENS WEIGHT (mg) 300 200 (n=) (26) AGE CLASS I I I (25) (10) I I I "rv" (16) V 300 200 100 B • NKl6)(3l6QC(14?)(g)0l2fl£(lO) (ft) (g) ( g f (2) (3) (2) (4) (1) (21) AGE 1 2 3 4 5 6 7 (Mo) 1 1 T - 1 1 1— 10 11 12 13. 14 15 VOLUME (mm3) 210 (:130. 180 . 150 • E H o I—I w 120 C O 90 60 30 KNOWN AGE PECCARIES l e n s wt= 4fc>.2'/ + b.y$~Tage) age= 0 . 1 4 ' l e n s ) - 6 . 0 1 ALL PECCARIES l e n s wt= 5 4 . 8 + 6 . 8 (age) age= .13 ( l e n s ) - 6 . 5 r= . 9 5 known age • e r u p t i o n age a 5 mo. 10 15 20 25 AGE Figure 2. Regression of lens weight on age of known-age peccaries 121 months old, and ©f a l l south Texas peccaries 124- months old. For prediction of age from lens weight, age i s dependent variable and the appropriate least squares l i n e s of best f i t are given by the second formula i n each case. 131 . those classes. Nutrition influences growth of the lens (Lord, 1963; Matschke, 1963; Friend, 1967b), p a r t i c u l a r l y i n the f i r s t phase of post-partum growth (Friend, .1967b; Friend and Severinghaus, 1967). Since peccaries are born throughout the year, and food conditions vary markedly from season t D season and year to year, the conceivable difference i n lens growth would make the use of the lens weight r i s k y f o r age determination. However, in my known—age sample were three 3.7 month old males, whose lens weight varied a maximum of 4.9D/o from the mean weight f o r the three animals (mean, 74.5 mg, range, 70.1 to 78.8 mg, S.D., 3.1 mg), while the carcass weights varied 84°/o from the mean for the three animals (mean, 6.6 lbs , range, 3.8 to 12.0 lbs , S.D., 4.7 l b s ) . Thus the eye lens weight i s much more con-servative than the body weight and therefore more accurate f o r age deter-mination. The same conclusion was arrived at by Dudzinsky and Mykytowycz (1961). Ranges of age at tooth eruption in the south Texas peccaries (Fig. 3) based on my pen—reared sample, indicate that i t i s s i m i l a r to that found in the Arizona peccaries (Kirkpatrick and Sowls, 1962), with some vari a t i o n . In the south Texas animals, molars and erupt about three months l a t e r than i n the Arizona peccaries, but M^  erupts e a r l i e r , and i t s posterior-most cusp i s not f u l l y erupted u n t i l the animal reached 25 months. The only other difference of consequence i s the eruption time of lower I . My data show that one animal s t i l l has i t s deciduous I ^ present at 15 months, at least f i v e months l a t e r than in the Arizona peccaries. In s i x 14-month old animals examined, the permanent I„ was i n place but had not been pre-sent at 12 months. Lower PM^i a n d PM^ were erupted or erupting in one ani-mal at 10 1/2 months, about f i v e months before eruption i n the Arizona pec-caries. This animal was captured as a baby of two to three weeks. The differences i n eruption times f o r the other teeth vary only s l i g h t l y . After the l a s t molar has f u l l y erupted at about two years old, i t was necessary to depend upon subjective estimation of wear on the cheek teeth to separate age groups i f the age of the animals was determined by tooth wear. The d i v i s i o n between Sowl's (1961a) age classes i s subjective and i t i s necessary to refer constantly to the standards set for d i v i s i o n of the continuum into groups. Separation of the f i r s t age class i s f a i r l y objective, and the upper l i m i t of the second wear class i s only a l i t t l e more i n d e f i n i t e . 132. FIGURE 3. Tooth eruption progression for south Texas peccaries. Lines i n -dicate presence of tooth; heavy portions show range of variation i n age at which tooth f i r s t appears. 134. The older groups are more d i f f i c u l t to separate and assign to age classes because they are based ondegree of wear of a l l of the teeth and unless a series of tooth measurements i s taken, as Lowe (1967) has done for red deer, i t i s d i f f i c u l t to be objective i n separation of the groups. Class 5 i s separated from 4 on the basis of extreme wear and loss of teeth. In some animals i t was apparent from other c r i t e r i a that they were not as old as a Class 5 group would indicate. Animal P-79, for example, probably l o s t a l l of i t s cheek teeth due to i l l n e s s or disease. In some animals maloclusion has resulted i n early loss of some teeth A variety of factors, notably food composition, can cause ir r e g u -l a r or different rates of wearing. Peccaries i n both south and west Texas areas consumed foods which are frequently coated with sand or dust p a r t i c l e s . This undoubtedly hastens tooth wear. In addition, although foods i n both areas are very-fibrous, the lechuguilla and.sotol commonly eaten by west Texas animals are probably more abrasive than the nopal p r i c k l y pear (0. lindheimeri) commonly eaten by south Texas peccaries. Thus tooth wear i n west Texas peccaries i s probably faster, and i f animals were "aged" by the same tooth wear c r i t e r i a i n the two areas, the west Texas peccaries would actually be chronologically younger than the south Texas animals i n a given age class. The older age classes should r e f l e c t t h i s difference to a greater degree. The l i m i t e d data i n Fig. 4 do indicate the difference i n degree of wear, but since most of the animals from west Texas were less than four years old, wear differences would not have had time to become accentuated. Annulations were v i s i b l e i n the cementum of a l l teeth examined, but were d i f f i c u l t to count i n some of them. As determined from the known-age animals up to 10 years 5 months, the annulation age i s within one year of the correct age i n the older animals, and i s more accurate i n the younger animals (Table 1). The accuracy probably decreased in animals over 10 years, but animals.aged to 15 years are probably within 2 years of the correct age. The sequence of deposition of cementum was determined on the animals collected i n south Texas, and the November-December c o l l e c t i o n from the Black Gap area confirmed the pattern. I t i s the same as for more northern ungulates. The discussion w i l l be l i m i t e d primarily to the permanent teeth. Annulations are l a i d down during the winter between October or November and March or A p r i l . By early May, a thin deposition of 'summer1 cementum i s v i s i b l e . Lamellae, as described by Nishiwaki, et a l . 135. Figure 4. Comparison of age determined by dental annulations (x-axis) and wear classes for south and west Texas peccaries. Sowl's Wear Classes •- LZl 1- m 2- g 3- H 4- a 5- • AGE IN YEARS 137. Table 1. Comparison of known-age and annulation age of peccaries pen-reared by L. K. Sowls i n Arizona, and during t h i s study at U.B.C. and the Welder Refuge. Anim. a No. Bir t h Date Death Date Known Age No. o f b Annuli Annulus Age c Comment S- 657 4-65 5-66 iy 1m 0+ 1 1/4 yr S- 671 9-65 . 8-67 2y 11m 2-3 yr F S-1142 1-56 5-66 10y 5m 9+d 9-11 yr S-1152 7-59 7-61 2y 2+ 2 1/2 yr P,A S-1155 6-57 5-66 8y 11m 8 + d 8 3/4 yr F S-1159 11-62 9-64 iy 10m 1+d 1-2 yr S-1435 6-55 1-65 9y 7m 9 9-10 yr P S-1535 7-58 6-65 6y 11m 6+ 6- 7 yr S-1566 5-57 1-62 4y 8m 4 4- 5 yr 4th forming Pc-154 Spring/65 8-67 2y 8m 2 + d l . t . 3yr F Pc-155 12-65 8-67 iy 8m 1++d 1 1/2 yr Pc-156 4-66 8-67 iy 9m 0++ 1 1/2 yr Pc-157 6-65 8-67 2y 2m 1++ 2 yr F Notes: a - S - series from Arizona, Pc- and J - series from Texas and U.B.C. b — + Indicates thin deposition of summer cementum following annulus ++ Indicates considerable deposition of summer cementum +++ Indicates s u f f i c i e n t summer cementum deposited that next annulus might be in process of form ing at outer edge of cementum c - P-poor d e f i n i t i o n of annuli; F - f a i r d e f i n i t i o n M-moderately good; G-good; P-G-some poorly, some well defined; A—several good annuli on canine root. d - F i r s t annulus in eruption cementum. 138. (1958), are v i s i b l e throughout the summer cementum in some of the teeth. In some years, i n some teeth, double annuli are formed as described by Low and Cowan (1963), with the less intense annulus following the intense annulus. Although peccaries breed throughout the year, there i s a-, major breeding season st a r t i n g from December to February, and i t i s possible the "rut" l i n e i s caused i n peccaries by hormonal changes associated with breeding. Further, annual food a v a i l a b i l i t y i n peccary habitat i s r e s t r i c t e d by moisture conditions, which vary seasonally as well as annually, and therefore are not consistent enough to cause an annual deposition occurring at approximately the same time each year. Thus, i t would appear that annulations in dental cementum are caused by a fundamental annual metabolic rhythm. I t i s interesting to speculate that i n those instances where a strong annulation i s l a i d down, i t may have coincided with a winter drought or food shortage. However, i n some animals (eg. P—12, Plate 1b) strong annuli are l a i d down every year, whereas i n other animals (eg. P-14, Plate 1c) weak annuli are formed every year. In s t i l l other animals (eg. P-81, Plate 1d) , a series of annuli are intense followed by a series of weak annuli. I t appears that deposition of the annuli are not under the strong influence of climate since the deposition pattern does not seem to be related to the cl i m a t i c pattern. There i s a change i n structure i n the f i r s t layer of "summer" cementum s i m i l a r to that described f o r mule deer by Low and Cowan (1963) (Plate 1a). I t i s probable that the more c e l l u l a r portion i s deposited dur-ing the period of rapid eruption and the less c e l l u l a r portion deposited after rapid eruption i s complete (Orban, 1944). Rapid eruption i s usually com-plete within a couple of months of the time that i t breaks throught the gums. The thickness of the f i r s t summer depostion varies considerably from animals born i n the spring to those born i n the f a l l . A spring born animal gets i t s permanent f i r s t i n c i s o r in the l a t e spring or early summer, thus the deposition of summer cementum i s r e l a t i v e l y thick by the time the f i r s t annulus i s formed. Conversely, the permanent f i r s t i n c i s o r of an autumn born animal erupts i n the autumn or winter, and an annulation would be de-posited almost immediately. In some cases, the f i r s t annulation i s present in the c e l l u l a r portion of the cementum deposited p r i o r to completion of the rapid eruption period. In counting annuli i n deer teeth, the changeover from c e l l u l a r to 139. Appendix C. Plate 1. Annulation i n tooth cementum. a. The method of counting annulations i n the cementum of the f i r s t i n c i s o r . The v e r t i c l e arrows show six d i s t i n c t and one i n d i s t i n c t annuli. The outside annulus was c l e a r l y evident i n other areas of the section. An eighth annulus was also v i s i b l e close to the dentino-cementum (D-C) interface in other parts of the section. "E" i s the zone of change from the c e l l u l a r rapid eruption to the less c e l l u l a r post-eruption cementum. Surface eruption of t h i s tooth starts at 13 to 15 months old. The f i r s t annulus v i s i b l e here.was judged to have started to form at 2 1/2 years (November of December) and would have been completed by 34 to 35 months (March). The l a s t annulation would have been formed by just under 9 years and the 2 months from completion of annulation deposition to death give an estimate of age of 9 years. The animal i s a known-age Arizona peccary (S-1155) known to be 8 years 11 months old. b. Strong annulations i n the cementum of an 8-year old south Texas female (P-12) k i l l e d in May. Seven annuli are v i s i b l e and several of these are double. The dentine i s at the bottom. The excessive c e l l u l a r i t y of the summer cementum following the fourth annulus i s unusual; c. Weak annulations i n the cementum of a 6—year old south Texas female (P-14) k i l l e d i n June. The dentine i s at the lower ri g h t . Five annuli are v i s i b l e . d. Faint and strong annulations i n the cementum female (P-81) k i l l e d in May. of a 10-year old 1.40. 141 . l e s s — c e l l u l a r cementum in the f i r s t summer can be mistaken for an annulus unless constant care i s taken. This i s also a problem i n peccaries (Plate 1a) with the added d i f f i c u l t y that an annulus could conceivably coincide with the changeover of cementum types. Hence, the region between the dentino—cementum interface and the f i r s t annulus outside the changeover re-gion of cementum types must be car e f u l l y scrutinized to determine presence or absence of an annulus. The tooth breaks through the gum at 13 to 15 months and t h e . f i r s t annulus could be deposited anytime between about 10 months and 22 months. To determine the age, I estimated the age at the time the f i r s t annulation i s deposited and added the number of annuli to that age. For example, i f the f i r s t annulus i s close to the dentino—cementum interface i n the 'pre-eruption' cementum, then the age at the time of formation of the f i r s t annulation i s between 10 and 16 months. The t o t a l number of annuli then represents the approximate age to the time of deposition of the l a s t annulation. I f the f i r s t annulation i s outside the changeover zone from c e l l u l a r pre-erupted to r e l a t i v e l y a c e l l u l a r post-erupted cementum, then the number of months between eruption time and annulation deposition was estimated from the amount of intervening cementum. This time, plus two mon ths ( average number of months over one year that the f i r s t i n c i s o r erupts), was then added to the t o t a l number of annulations present to ar-r i v e at the age at time of deposition of the most recent annulation. The correct age i s then determined by adding the number of months elapsed between time of death and March (the time at which summer cementum deposi-tion s t a r t s ) . The location of the f i r s t annulus i s an indicator of the approxi-mate time of the year that the animal was born. I f i t i s close to the zone of change from r e l a t i v e l y c e l l u l a r to r e l a t i v e l y non-cellular cementum, then the animal was born in the f a l l or l a t e summer. I f i t i s r e l a t i v e l y d i s -tant from the eruption zone, then i t was probably born i n the spring. The series of known—age teeth (Table 1) show that there i s some discrepancy i n the age determined from annulations when compared to the known age. However, t h i s occurs in those animals that have poorly defined annuli (eg. Plate I c ) . In those animals which have well defined annuli (eg. Plate lb) the assessment of age i s quite accurate. In no case does the determined age depart by more than one year from the known age. Annulations were only moderately easy to interpret in about 66°/o of the teeth from Texas peccaries. In these animals the assessed age i s pro-bably quite accurate. In the other 34% d i f f i c u l t y of counting annuli varies 142. from d i f f i c u l t (17.5%) to almost impossible (16.5%) to count. The canine tusks of peccaries are open—rooted and are continuously being forced.upward by deposition of dentinal cones inside the root i n the manner of the Phocids (Laws, 1962). As a res u l t , the canine root canal of the known-age peccaries progresses from a wide open s h e l l at eruption, to greatest size of opening at 2 to 3 years when the tooth has reached i t s maximum size, to almost closed at about 10 years. The root of the canine of a 10 year 5 month old Arizona peccary was only s l i g h t l y open. Several of the south Texas peccaries collected from the King Ranch had canines i n which the root canal was closed. These animals were a l l determined by annulation count to be over 12 years old, except for P-113. This animal's canine was extremely worn down and the root was severely eroded. I t s estimated age of 10 or 11 years i s probably conservative. The resul t of the growth pattern of open-rooted teeth i s a pattern s i m i l a r to that drawn by Godin (in Mosby, 1963: 153, Fig. 6. 23) in the cementum. In peccary canines, only the f i r s t two or three rings are obvious along with numerous lesser annulations on the sur-face of the root. Measurement of the length of the canine exposed above the gum has been suggested as a possible indication of age. This i s not feasible be-cause the tooth reaches i t s maximum exposed length at three to four years. Thereafter, the rate of wear exceeds the rate of eruption, and the exposed length decreases. I t i s apparent from Fig. 4 that age determined from annulations generally f a l l s into the groups determined from tooth wear, with the excep-tion of animals older than seven or eight years. These animals are in age classes 4 and 5, and they f a l l i n these groups in an irr e g u l a r fashion. Thus i t i s probable that age classes 4 and 5 should be more r e a l i s t i c a l l y treated as a single group when age associated characters are being examined. How-ever, When condition—associated characters ( i . e . dependent upon the animals a b i l i t y to obtain food) are being examined, i t could be useful to recognize f i v e age classes (Fig. 4). Age Class 1 contains animals that are between two and three years old. Age Class 2 contains animals that are between three and approximately f i v e years old. Age Class 3 contains animals that are f i v e to seven years old, and Classes 4 and 5 contain animals older than seven years up to about 15 years. 143. '1.3. Conclusions The most p r a c t i c a l and accurate methods of determining the age of peccaries involved the teeth. Eruption patterns are easily obtained and accurate within two months f o r animals up to 25 months old (the age at which the l a s t permanent tooth completes eruption). Dental cementum annulations provide a means of determining age, accurate within one year, for animals that are older than one year, i n those animals i n which annuli are c l e a r l y defined. In animals with poorly defined annuli, consideration of age class, canine root closure and lens weight a s s i s t i n the interpolation of the annuli, and used j o i n t l y a r e l a t i v e l y accurate age can be determined. For young animals i n the rapid growth stage less than 24 months old, the lens weight appears useful for age determination. A regression l i n e y = 0.15x - 6,6 was established f o r the known-age animals less than 24 months old. 2. Age Determination Of Foetal Peccaries Two methods of estimating age of foetuses were used. Growth curves of demestic pig foetuses (Ullrey, et a l . , 1965) and b l a c k t a i l deer foetuses (Thomas, 1970) drawn so that the gestation periods (114 and 203 days, respectively) and crown-rump lengths (at 5 and 4 intervals respective-ly) were plotted i n the same i n t e r v a l showed that the growth curve during the l a s t 75°/a of the gestation period fallowed straight l i n e s which almost coincided' (Fig. 5). No information was available on the i n i t i a l 25°/o of the gestation period. These species were chosen because they represented l i t t e r sizes and gestation periods either side of peccary l i t t e r size and gestation period. I assumed that i f the curves f o r these species coincided, then the curve should be applicable to peccary foetuses. Peccary gestation time of 144 days (Sec. 4.6,) and the crown-rump length at pa r t u r i t i o n (10 inches) were plotted i n the same intervals as for the other two species. One known-age l i t t e r of.: peccaries obtained at an average crown-rump length of 6.8 inches at 105 days coincided almost per-f e c t l y with the curves f o r the other two species (Fig. 5). Foetal age was then determined by taking the crown-rump length of the foetuses and locating i t s corresponding age on the chart. A second method employed the weight of the foetuses. Hugget and Widdas (1951) determined from a comparative analysis that f o e t a l weight of 1 /3 mammalian species could be determined from the formula W = a ( t - t ), where o ' W i s foetus weight, 'a:' i s the s p e c i f i c f o e t a l growth ve l o c i t y , ' t ' i s the L E N G T H = Figure 5. Crown-rump growth curve^ of.foetal domestic pig and black-tailed deer, plotted i n the same i n t e r v a l , and used for predicting the age of f o e t a l (peccaries..:; ' • 145. gestation age, and 't 1 i s the early portion of pregnancy before "stable" environmental conditions provided by an adequate symbiotic relationship" are established. They have estimated that 't ' for species with a gestation o period of 100 to 400 days i s 0.2x (gestation period) and 0.3x (gestation period) for a gestation period..of 50 to 100 days. Hence, I used a factor of .25x (gestation period), and determined that for.peccaries, 't ' i s °1 /3 38 days. 'a' i s determined by substituting into the formula a = W / t - t ^ , the values of 'W and ' t ' at any known time during gestation. Thus, at pa r t u r i t i o n 'W = 728 gms (Table 10), ' t ' = 144 days and 'a' = .086. However, i f the data for the 101 days old foetuses are substituted, then 'a' = .098. The mean of these two s p e c i f i c growth rates f o r peccaries i s .092. I f these values are then used to determine ' t ' i n the transposed formula, 1 /3 t = (W /.092) + 38, the approximate gestation age of the foetuses can be determined. This has been done to arrive at the post-conception age (weight) in Table 2. Application of the two methods using the weight and length of the foetuses of U.B.C. female Pc-168, results i n ages of 121 and 125 days, re-spectively. The results agree f a i r l y closely for the two methods. Rela-t i v e to the age determined from the body length, age determined from body weight i s over—estimated i n early gestation and underestimated i n l a t e gestation. At just over 100 days, the results are about equal. I have estimated the ages of foetuses collected during the study from crown-rump length and from body weight. Crown—rump length has been shown to have a more precise.' relationship to foetus age than does body weight" (Ommundson, 1967). The ages established f o r the foetuses are shown i n Table 2. The gestation age derived i s referred to as post-conception age (length) and post conception age (weight), respectively. Several foetuses were collected that were larger than average post-parturants. Where th i s occurred, the foetuses were aged as 'term'. In one case, the post—conception age (length) was term, whereas the post-conception age (weight) was only 105 days. No explanation i s available for the disparity. In another case, the female foetus of a set of twins was 382 grams, and the male was 847 grams. Using the means for both weight and length, the age was estimated at 130 and 137 days. I t was evident from the morphology of the foetuses that they were very near term. Thus the extremely slow growth of the female pul-led down the age estimated. Such cases of extremes were very few. Post-conception age less than 50 days i s extremely inaccurate and not to be re-146. Table 2. Estimate of age of foetuses from crown-rump length and weight (see t e x t ) . Post-conception |y|B  Age (days) c°ncep' Sow foetuses x wt. (gm) x Length wt. length (cmj P6 2 339.6 19.25 114 116 Dec 24/64 P8 2 431 .8 21.6 120 142 Dec 20/64 P1D 1 515.2 22.2 125 128 Dec 15/64 P12 1 972 28.6 146 Term Dec 21/64 P13 1 665 25.0 133 141 Jan 13/6^ 5 P14 1 5.2 4.1 57 46 May 6/65 P17 3 74.1 11.5 84 78 Apr 8/65 P18 2 691 .5 24.5.. 134 138 Feb 16/65 P21 2 .17 1.4'' 44 20-30 Jun 7/65 P28 2 130 13.9 93 87 May 25/65 P31 1 20-25 Aug 1/65 P32 2 127 14.0 93 88 May 29/65 P34 2 305.6 19.1 111 112 May 26/65 P35 2 358.3 20.8 115 121 May 20/65 P42 2 357.3 19.9 115 116 May 22/65 P54 2 563 26.0 128 Term Sep 19/65 P56 2 31.4 7.7 72 61 Nov 30/65 P57 2 141 .5 13.4 95 85 Nov 6/65 P60 2 93.0 12.6 87 82 Nov 16/65 P67 2 10.7 - - 62 Jan 4/66 P71 2 234.7 26.5 105 Term Nov 26/65 P74 2 494.5 22.4 124 128 Nov 25/65 P79 1 2.7 — - 53 Mar 26/66 P81 2 '614.5 24.3 130 137 Jan 6/66 P95 3 87.9 12.8 86 84 Mar 22/66 P98 2 — — 14.1 89 Mar 18/66 P111 1 265 19.4 108 113 Mar 19/66 P119 1 77.5 11.4 84 77 Nov 15/66 P127 2 245 — — 106.0 Dec 28/66 P130 2 2 — - 52 Apr 1/67 P133 2 349.9 - — 114.6 Jan 27/67 P139 1 132.8 — — 93.4 Mar 4/67 P140 2 8.8 5.5 60 52 Apr 20/67 Pc154 1 96.6 12.7 88 83 May 27/67 Pc168 2 440 22.1 121 127 Jan 12/68 Pc180 3 237.3 17.1 105 102 Feb 27/68 P66 2 497.8 23.0 124 131 Oct 24/65 Pc181 2 4 c e l l stage Known —2 days WT15 2 111 .3 13.4 90- -86 days Mar 30/66 BG 67-1 1 1 .2 1 .8 10- -20 days Jan 1/67 Note: a- the mean conception date i s the approximate date of conception de-termined by backdating of the foe t a l ages derived from the two methods. 147. l i e d upon, because t h i s l e v e l f a l l s below the steady growth phase of Hugget and Widdas (1951). With the approximate gestation age established, the corresponding conception date was determined by subtracting the gestation age from the date of c o l l e c t i o n . This has been done i n Table 2. 148. Appendix D. Table 1. Age-specific weight and body measurements of peccaries collected i n south Texas. (See notes following Table 2.) Measurement Age Males Females (years) 95% C.I. n X 95% C.I. n D i f f . Prob. Live weight 1-1 .9 44 2 40 7.8 5 .2 n.s. (pounds) 2-2.9 45 3.5 11 44 4.6 7 1 .7 n.s. 3-3.9 48 6.9 5 49 4.9 7 1 .0 n.s. 4-4.9 48 5.8 6 48 5.5 4' 0.1 n.s. 5-5.9 52 4.4 8 51 5.1 11 1 .7 n.s. 6-6.9 52 4.8 8 53 4.1 6 0.3 n.s. 7-7.9 53 2 56 2 3.0 n.s. 8-15 53 2.5 10 52 2.2 19 0.9 n.s. 3-15 52 1,7 39 52 1 .6 49 0.3 n.s. Carcass weight 1-1 .9 27 1 25 4.8 6 2.0 n.s. (pounds) 2-2.9 30 2.8 11 28 2.5 8 2.7 n.s. 3-3.9 32 9.1 4 30 3.8 7 2.1 n.s. 4-4.9 32 5.1 6 34 5.6 4 2.0 n.s. 5-5.9 36 4.7 7 32 3.4 11 3.7 n.s. 6-6.9 35 2.8 8 32 3.0 6 3.4 .08 7-7.9 38 2.4 2 35 9.3 2 3.1 n.s. 8-15 36 2.0 10 32 2.3 18 5.1 .01 3-15 35 1 .4 37 32 1 .2 46 2.9 .01 Total length 1-1 .9 36 1 37 1 .7 7 0.3 n.s. (inches) 2-2.9 38 0.6 11 37 .7 7 0.6 n.s. 3-3.9 37 2.1 4 38 1 .5 7 0.8 n.s. 4-4.9 38 1 .3 6 40 1 .4 4 1 .8 n.s. 5-5.9 39 1 .4 8 39 1 .5 11 0.3 n.s. 6-6.9 38 1 .3 8 39 1 .3 6 0.9 n.s. 7-7.9 38 2.6 2 37 1.1 2 1 .4 n.s. 8-15 39 0.9 9 39 0.6 18 0.4 n.s. 3-15 38 0.5 38 39 0.4 48 0.7 .05 Girth 1-1 .9 24 1 20 0.9 7 3.4 n.s. (inches) 2-2.9 23 0.8 10 22 1 .2 6 0.4 n.s. 3-3.9 23 1.1 4 22 1 .7 7 0.3 n.s. 4-4.9 22 1 .2 6 24 1 .0 4 2.0 .01 5-5.9 24 1 .4 8 23 0.8 11 . 11.1 n.s. 6-6.9 23 1 .4 8 23 1 .9 6 0.7 n.s. 7-7.9 22 1.1 2 24 2.6 2 2.3 n.s. 8-15 24 1.1 8 22 0.7 17 1 .5 .01 3-15 24 0.6 37 23 0.4 47 1 .4 n.s. Hind leg 1-1 .9 6.7 1 .5 3 7.2 0.1 7 0.5 n.s.s (inches) 2-2.9 7.1 0.2 11 7.2 0.1 8 0.1 n.s.s 3-3.9 7.1 0.2 4 7.2 0.3 7 0.1 n.s. 4-4.9 7.0 0.4 6 7.3 0.2 4 0.3 n.s. 5-5.9 7.3 0.1 8 7.2 0.1 11 0.1 n.s. 6-6.9 7.3 0.2 8 7.3 0.1 6 0 n.s. 7-7.9 7.3 1 .1 2 7.4 0.4 2 0.1 n.s. 8-15 7.3 0.1 9 7.3 0.1 18 0 n.s. 3-15 7.2 0.1 38 7.2 0.1 48 0 n.s. 149. Appendix D. Table 2. Age-specific weight and body measurements of peccaries collected i n west Texas. Measurement Age Males 9 Females L_ (years) X 95% C.I. n x" 95°/o C.I. n D±ffb. r, , C Prob. .. Live weight 1-1 .9 43 1 (pounds) 2-2.9 45 7.2 3 43 3.8 2 2. n.s. 3-3.9 40 12.7 2 47 2 7. n.s. 4-4.9 46 17 3 46 17 3 3+ 39 5. 4 46 7. 5 7. n.s. Carcass weight 1-1 .9 27 3.6 14 26 2.4 12 0.7 n.s. (pounds) 2-2.9 32 1.8 22." 31 2.2 14* 1.1 n.s. 3-3.9 28 4.6 3 28 7. 4 0.6 n.s. 4-4.9 32 6.3 3 . 31 3.9 6 1.6 n.s. 5-5.9 33 3.5 8 30 2 3.5 n.s. 6-6.9. 0 31 9.3 3 7-7.9 40 1 0 8+ 36 15 4 34 8.5 4 1 .8 n.s. 3+ 33 1 .9 27 31 1 .7 25 2.5 .01 Total length 1-1 .9 35 1 .4 14 36 1 .4 11 1 .0 n.s. (inches) 2-2.9 38 0.9 21 37 1 .0 14 0.9 n.s. 3-3.9 39 4.4 3 37 5.2 4 2. n.s. 4-4.9 37 5.0 3 39 2.1 6 1 .9 n.s. 5-5.9 37 1 .6 8 40 2 3. n.s. 6-6.9 40 4.8 3 7-7.9 40 1 8+ 38 4.2 4 38 2.8 4 0.7 n.s. 3+ 38 0.8 27 38 0.9 26 0.2 n.s. Leg length 1-1 .9 7.6 0.2 14 7.6 0.2 12 0. (inches) 2-2.9 7.4 0.1 22 7.6 .1 16 0.2 n.s. 3-3.9 7.1 0.3 3 7.6 , .1 3 0.5 n.s.s 4-4.9 7.8 . .7 3 7.4 .3 6 .4 n.s. 5-5.9 7.6 .2 8 7.2 2.5 2 .4 n.s. 6-6.9 7.6 0.9 3 7-7.9 7.5 1 8+ 7.4 4 7.4 4 0 3+ 7.5 .1 20 7.5 .1 25 0 Note: a - Values given are the mean, the 95°/o confidence Interval and the sample s i z e , b — difference. c - probability of difference being s i g n i f i c a n t . Appendix E. Spermatogenic a c t i v i t y of a selected series of testes from the collared peccary. Age . . ., a Animal Date Weight T.Ib Spermatogenesis c Tubule0*. percent No. C o l l . Testis -cytes - t i d s sperm diam. tubules South Texas and pen--raised peccaries 1 day Pc174 Jan/69 no no 0 52.9 u 30 1 day Pc177 Feb/69 ,07gm 0.023 no no 0 55.9 41 3 months P-52 Nov/65 1 .0 0.16 no no 0 56 60 3.7 mo. Pc158 Aug/67 2.6 0.55 v.f. no 0 71 .4 29 3.7 mo. Pc159 Aug/67 0.7 .32 v.v.f. no 0 60 35 7 mo. P*55 Feb/66 2.0 .52 few no 0 67 40 7 mo. P-62 Mar/66 3.0 .54 few no 0 78 38 8 mo. P-83 May/66 6.0 .92 mod. no 0 115 30 10 mo. P-70 Mar/66 6.5 .98 mod. few 9.2 130 39 9 mo. P-128 Apr/67 6.5 1.-1 few v.f. 0.2 123 39 11 mo. P-109 Aug/66 9.8 1 .3 mod. few 35.6 192 59 1.5. yr. Pc156 Aug/67 15.7 2.1 num. mod. 55.2 165 80 1.8 yr. P-16 Jun/65 10.0 1 .2 num. mod. 28.7 156 56 1 .8 Pc155 Aug/67 18. 2.7 mod. num. 60. 201 67 2.2 P-131 May/67 18.7 2.7 mod. mod. 95.4 211 70 2.2 P-137 Jun/67 22.5 3.0 mod. mod. 90.6 160 74 2.2 P-144 Jun/67 12.7 1 .8 num. num. 64.4 147 73 2.5 P-41 Sep/65 14. 1 .9 num. num. 81 .2 203 65 3.5 P-19 Jun/65 18.5 2.5 mod. num. 98.2 200 70 3.8 P-120 Feb/67 13.6 1.9 mod. mod. 57.8 187 81 4.0 P-63 Mar/66 16.1 2.5 num. num. 109.4 188 53 4.5 P-116 Oct/66 16.3 2.3 num. num. 88.8 160 65 4.7 P-29 Aug/65 16.1 2.3 num. num. 95. 196 82 4.8 P-112 Aug/66 16.1 2.2 num. num. 70.4 168 60 5.8 P-38 Sep/65 21.9 3.0 num. mod. 38.0 210 62 5.8 P-59 Feb/66 19.2 2.7 num. num. 109.2 201 86 6.2 P-149 Jul/67 22.5 3.0 num. mod. 75.2 160 76 8.2 P-106 Jul/66 17.4 2.6 num. num. 123.7 212 80 8.8 P-51 Nov/65 a8.6 2.5 num. mod. 77.0 201 61 9.2 P-126 Mar/67 25.9 3.4 num..- num. 97.2 203 76 12.0 P-5 l e f t Apr/65 31 .7 3.1 num. num. 155 181 54 right 12.9 mod. mod. 60.6 154 26 14.0 P-86 May/66 16.8 2.3 num. num. 75.8 182 81 (cont'd....) Appendix E (cont'd) Age Animal 9 Date Weight- T.I. b Spermatogenesis c Tubule^ percent 8 No. C o l l . Testis —cytes - t i d s sperm diam. tubules West Texas peccaries 2.0 yr WT-14 Jun/66 10.7 1 .4 num. num. 38.8 198 52 2.9 WT-16 Sep/66 14.6 2.0 num. num. 103 191 68 ad.(old) WT-2 Jan/66 9.6 1.3 num. num. 80.5 205 66 9.2 WT-1 Nov/65 -.10.5 1 .4 num. mod. 40.4 191 87 5. (est.) BG5-25 Dec/65 17. 2.3 num. num. 78.0 . 226 52 1.3 yr BG5-7 Nov/65 6,.0 O.S num. mod. 24.6 154 50 Notes: a - Pc denotes pen-reared animal ID —• Testis index = Testis weight Hind foot length c - Spermatocytes include both primary and secondary; abbreviations are: no = none, v.v.f. = occasional, v.f. = very few, mod. = moderate, num. = numeroussperm counts are the average number/tubule cross section determined from f i v e tubule cross sections. d - tubule diameter i s the average diameter of f i v e tubules; in microns. e - proportion of t e s t i s composed of tubules; determined with microscope occular g r i d . 152. Appendix F. Age-specific size of ovaries and several ovarian structures. In these tables, ovaries from sows less than two weeks pregnant were placed with non-pregnant animals because i t i s d i f f i c u l t to ascertain whether a sow i s pregnant or not pregnant during the f i r s t two to three weeks of pregnancy. Their corpora lutea are s t i l l r e l a t i v e l y small. Also, included with the non-pregnant sows were those which had degenerating corpora lutea. In one case the sow was only about 12 hours post-partum and 3 the corpora were s t i l l 500 mm . These corpora add considerable v a r i a b i l i t y to the size of the ovary. Appendix F. Table 1. Age-specific weights and volumes of ovaries and ovarian structures of pregnant and non—pregnant south Texas peccaries. Preserved Preserved Sectioned Age Ovaries Ovaries •) Ovaries Medull 5\ Lgst CL Lgst Fo V-(years) Wt. (gm) Vol (cc Vol ( mm ) Vol (mrr ) Vol. (mm ) Vol . (mm ) X SE n X SE n X SE n X SE n X SE n X SE n NON-PREGNANT Foetal .028 .007 14 4 (4) 0.7 (4) <1 .4 .1 8 .6 .1 (8) 245 81 (8 97 3 (8 6.2 1 .5 (5) 1-1 .9 .7 .1 (7) .7 .1 (7) 368 52 (7) 144 14 (7) 0.4 o: (2] 9.1 1 .8 (7) 2-2.9 .8 .1 (5) .9 .1 (5) 537 89 (5) 185 18 (5) 190 140 13.4 2.5 (5) 3-3.9 1 .0 .2 (4) 1 .0 .2 (4) 577 148 (4) 126 35 (4) 157 12 ( 3 : 22.9 7.8 (4) 4-4.9 1.1 .2 (2) 1.1 .2 (2) 747 171 (2) 209 31 (2) 77 65 ( 2 : 6.2 .9 (2) 5-5.9 1.1 .3 (4) 1 .2 .3 (4) 650 147 (4) 126 27 (4) 86 68 19.3 4.5 (4) 6-6.9 0.9 (1) 1 .0 (1) 494 ( 0 88 (1) 43 ( 1 7+ 1.1 .2 (6) 1.1 .2 (6) 494 34 (6) 85 18 (6) 93 53 (6) 6.2 1 .4 (4) ALL 2 yr.N.P.I.0 .1 (22) 1 .0 .1 (22) 570 44 (22) 134 14 (22) 117 35 (14) 13.6 2.2 (21) PREGNANT 1-1 .9 2-2.9 1 .6 .1 (2) 1 .6 .3 (2) 989 204 (2) 125 21 (2) 467 67 (2) 12.9 .9 (2) 3-3.9 2.0 .3 (2) 2.0 .4 (2) 862 226 (2) 157 64 (2) 329 126 (2) 7.24 0 ) 4-4.9 2.3 .2 (2) 1 .9 .1 (2) 1338 146 (2) 115 18 (2) 688 187 (2) 4.6 .8 (2) 5-5.9 2.5 .1 (7) 2.6 .2 (7] 1317 109 7] 121 24 ?] 669 55 ( 7 ) 165 8.5 i7) 6-6.9 2.1 .1 (5) 1 .9 .1 1241 104 5 110 21 5 653 103 (5 21 .9 5.9 5 7-7.9 2.0 .1 (2) 1 .7 .2 (2) 1241 112 (2) 89 8 (2) 620 92 (2) 9.05 (1) 7+ 2;3 .1 (13) 2.2 .1 (13) 1236 76 (13) 125 10 (13) 575 51 (13) 10.0 .9 (11) ALL Preg. 2.2 .1 (33) 2.2 .1 (33) 1221 47 (33) 121 8 (33) 594 33 (33) 13.0 2.4 (28) Appendix F. Table 2. Age sp e c i f i c weights and volumes of ovaries and ovarian structures of pregnant and non-pregnant west Texas peccaries. Acre. Preserved Wt. Ovaries Preserved Vol. Ovaries issl Vol. Sectioned Ovaries (mm ) Vol. Medulle (mm ) Vol. Lgs;t. CL (mm ) Vol. Lgst^ F o i l (mm ) SE SE SE SE SE SE NON-PREGNANT 1 1- 1 .9 2- 2.9 3- 3/9 4- 4.9 5- 5.9 6- 6.9 7+ 0.3 0.6 0.7 0.7 1 .2 1 .3 1 .2 0.9 .04 (4) (0. (8) (2) (4) (2) (2) 111 .1 .1 .2 .2 .3 0.4 0.7 0.7 0.8 1.1 1 .2 1.1 0.9 .1 (4) .1 (4) •1 (8) •3 (2) .1 (4) .1 (2) •8 (2) LU 200 355 399 405 604 616 613 518 28 10 80 149 51 126 347. (3) (4) M (2) (4) (2) (2) 111 93 179 120 50 187 47 81 79 27 41 25 22 57 22 2 3) 4) 7) 2) (4) (2) (2) H I 232 241 182 306 524 145 95 71 31 (6) 0 ) (4) (2) (1) III 1 .9 10.5 8.0 7.9 16.7 7.5 9.9 22.6 1.9 (2) 2.7 (4) 1.1 (10) .4 (2) 2.9 (5) 1.2 (2) •0 (2) LIL ALL 2 yr. NP 0.9 .1 (20) 0.9 .1 (23) 511 50 (19) 114 18 (19) 243 46 (15) 11 PREGNANT 2-2.9 2.0 (2) 4-4.9 1 .6 (1) 7+ 1 .4 0) A l l Preg. 1 .7 (4) 2.3 1 .5 1 .5 (1) (1) 111 1081 750 781 (2) (1) HI 145 91 102 (2) (1) 111 584 514 628 86 (2) (1) H i 9.1 7.7 9.7 (1) (1) 111 1.8 .3 (3) 923 142 IH 121 15 577 42 (4) 8.9 155. Appendix G. Mortality factors affecting peccary populations. Although a large number of factors are poten t i a l l y capable of causing mortality of individuals, few are important at the papulation l e v e l . I had the opportunity to examine several factors which were either thought to be important to peccary populations, or which were pote n t i a l l y capable of affecting the populations. These factors were predation, para-s i t e s and disease and the combination of cold weather and poor n u t r i t i o n . 1. Predation Despite suggestions by many authors (Knipe, 1958; Jennings 5 Harris, 1953; Neal, 1959b; Murie, 1951] I have found l i t t l e evidence to implicate predators as an important controlling mechanism for peccary populations i n Texas. In 1966, I examined stomach contents of coyotes and bobcats k i l l e d by the U.S. Fish and W i l d l i f e Service predatory animal trapper on the Santa Gertrudis Division of the King Ranch between June and September, 1966. The major portion of the contents were i d e n t i f i e d by examining the bones, hair or feathers i n the f i e l d , and material which could not be readily i d e n t i f i e d was taken back to the laboratory and compared with i d e n t i f i e d specimens. Cotton rats were the most common food item and were found i n the stomachs of 56% of the coyotes, 47% of the bobcats and of the only gray fox (Table 1). Wood rats, c o t t o n t a i l s , and Bobwhite quail were present in the stomachs of a small proportion of the predators. Only one coyote stomach contained parts of a w h i t e t a i l deer fawn, and only one bobcat stomach contained the fresh remains of a baby peccary. Many coyote scats were examined throughout the study and only one of them had young peccary hair present. Table 1. Stomach contents of canid and f e l i d predators trapped on the Santa Gertrudis Div., King Ranch. Cotton Wood Cotton-Species No. Empty Rat Rat - t a i l Quail deer Peccary Bobcat 34 10 (29%) 16 (47%J 4 (12%J 4 (12%J 1 (3%J 0 1 (3%) Coyote 41 15 (37%) 23 (56%) 2 (5%) 0 2 (5%) 1 (2%) 0 Gray Fox 1 1 (100%)  Total 76 25 (33%) 40 (53%) 6 (8%) 4 (5%) 3 (4%) 1 (2%) 1 (1%) 156. The predators i n the area made extensive use of rodents as a food source (Table 1) during the period when baby peccaries were abundant i n 1966 (text F ig. 22). The cotton rat population was very high (120/Acre) at the time following a favorable winter and good r a i n f a l l i n the spring (v.W. Lehmann, pers. comm.), and probably acted as a buffer f o r birds and large mammals during the period when the young might be vulnerable to predation. This si t u a t i o n would adequately explain the low frequency of baby peccary remains i n stomachs of predatory mammals during the period of c o l l e c t i o n . Knowlton (1964), working on the Welder Refuge, found that coyotes were opportunists and made use of the food which was most abundant at the time. He found l i t t l e evidence to indicate that coyotes preyed upon peccaries at the Refuge, probably because of the high deer population (White, 1966), the several species of rodents that fluctuate i n density i n a sequential manner on the Refuge (G.R. Raun, pers. comm.; Powell, 1967), and the good crops of mesquite beans and p r i c k l y pear tunas. Of 44 peccaries found dead i n the f i e l d i n south Texas, the cause of death of only 22 could be determined with reasonable certainty and only one of these, a piglet 1 to 2 weeks old, was d e f i n i t e l y attributed to predation (Table 2). Two other peccaries were found recently dead on the Welder Refuge and two on the King Ranch with the l a t e r a l abdominal area slashed open and various organs protruding, but otherwise untouched. These slashes were not unlike those;present on the haunches, shoulders-and cheeks of some live-trapped peccaries and were probably i n f l i c t e d by the large canines of other peccaries. Table 2. Cause of death of peccaries found dead in south Texas. Winter Un-Year Number Predator D.O.R.3 Fight Mort. Shot Trap known 1964-5 26 1 2 2 4 17 1966 5 2 1 3 1967 14 2 7 1 4 Total 45 1 2 4 10 4 .1 24 Note: a - Dead on road My evidence indicates that predators do not prey upon baby pec-caries when rodent populations are high. Lack of evidence throughout 157. the remainder of the study i n both west Texas, where predators are scarce, and south Texas, where predators are abundant, suggests that predation i s of l i t t l e importance i n peccary population dynamics. 2. Parasites and diseases Although parasites and diseases seldom have been implicated as factors c o n t r o l l i n g natural populations, the potential nevertheless exists (MacLulich, 1937; Bandy, 1968). During the l a s t half of the study (June, 1966 to August, 1967), we conducted a survey of endo-and ecto-parasites of the peccary mainly i n south Texas, but also i n west Texas. The results of t h i s study have been published (Samuel and Low, 1970). In t h i s study, we found nine endoparasitic species and s i x species of t i c k s , fleas and l i c e on peccaries collected mainly i n south Texas (Table 3), Blood serum samples were collected from peccaries throughout the study i n south Texas. The samples were frozen and shipped to the University of Wisconsin where metabolic i n h i b i t i o n tests (Cook, et a l . , 1965) were run for virus antibodies of Eastern equine encephalitie (EVE), western equine encephalitis (WVE), C a l i f o r n i a equine encephalitis (CVE), St. Louis equine encephalitis (SLVE), Venezuelan equine encephalitis (WE) and New Jersey and Indiana strains of vesicular stomatitis virus (VSN and VSI). Of the 49 serums examined to date 14% reacted to EVE, 6% to WVE, 4% to SLVE and 4% to VSI. No reactors to CVE, WE or VSI were found. A l l of these animals appeared i n good health, so i t must be assumed that while the viruses were active on the King Ranch, they were not f a t a l . In only one case was there any evidence of i l l n e s s i n the peccaries that were collected. This was an 8—year old sow that had 8,717 of the nematode, Parostertagia heterospiculum i n the lumen of the small i n -testine. She had swollen a x i l l a r y and abdominal lymph nodes and a kidney fat index of 0. The high helminth load may have been the cause of i l l n e s s , but there i s no evidence of direct cause and effect. I t must be concluded that mortality of peccaries caused by para-s i t e s and diseases i s not important to the .population i n either south Texas or west Texas. 3. Nutrition and cold weather. In south Texas, i t i s unlikely that food r e s t r i c t i o n s alone ever cause mortality of adult peccaries. However, when combined with 158. Table 3. Prevalence and abundance of parasites of the collared peccary i n Texas (from Samuel and Low, 1970) South Texas 3 West Texas Species Prevalence Abundance Prevalence Abundance Protozoa , , Balantidium sp 4% (25) — 0% ( 4 ) Nematoda D i r o f i l i a r i a acutiuscula C 27% ( 48) C 2(1-5) 0% ( 7 ) Gongylonema b a y l i s i " 4% ( 46) 1 0% ( 4)^ Parabronema pecariae 36% ( 53) 5(1-28) 0% ( 4 ) Parostertagia hetero- , spiculum 91% ( 58) 476(7-8717)0% ( 4 ) Physocephalus sp. 86% ( 56) 55(1-370)0% ( 4) Texicospirura t u r k i 48% ( 58) 7(1-48) 0% ( 4) Cestoda Moniezia benedini 9% ( 58) 1(1-3) t r% ( 4 ) b ' Trematoda Fascioloides magna 1% (144) 2(2-3) C P/o (21) — — Ixodidae Dermacentor v a r i a b i l i s Amblyomma cajennense Amblyomma inornatum Haemaphysalis l e p o r i s -p a l u s t r i s ^ 78% 98% 5% 7% ( 42) ( 42) ( 42) ( 42) 3(1-5)(3) 116(62-167) (3) 1(0(3) 2(2)(3) 0%(22) 0%(22) 0%(22) 0%(22) Siphonaptera Pulex porcinus 100% (313) 85(35-192)77%(22) e (4) 38(0-50] (3) Amoplura Pecaroecus j a v a l i i 0% (313) 8 8 % ( l 7 ) d 12(5-29) (6) average number per infected host (range) (number examined i f d i fferent than in;.prevalence column; only t o t a l c o l -lections included). b - Based on examination of feces only. c - Not previously reported from the collared peccary i n North America. d - An additional 52 animals fromithe Black Gap Area were negative for adult P. j a v a l i i , although egg cases were found on four of 14 peccaries close-l y examined for egg cases. e - Includes f i v e peccaries from the Black Gap Area which were negative of f l e a s ; a l l 17 peccaries from the Watson Ranch were positive. 159. other stress factors, n u t r i t i o n appears to be important to s u r v i v a l . During the winter of 1966-67, the temperature remained very cold f o r well over a month i n south Texas (text F i g . 2, a & b). Concurrently, south Texas was i n a severe drought (text Figs. 3 and 5) and p r i c k l y pear was the main food source (text F ig. 6). Two herds were under close surveillance during t h i s period; one on the Welder Refuge had 27 members and the other i n the north end of Mesquite Pasture on the King Ranch had 18 members. The Welder herd decreased by 26% between l a t e December and l a t e January with the death of seven peccaries ranging i n age from 7 months to 13 years. The car-casses of four of these animals were found a l l intact and some fresh, and a l l had boluses of p r i c k l y pear f i b e r s taking up over half of the volume of the stomach. In the three fresh specimens, body and i n t e s t i n a l f a t were almost lacking. In addition coat color of many of the peccaries, both l i v e and dead, had turned to the pale, reddish coloration associated with poor condition. On the King Ranch, the Caldwell M i l l , herd decreased 33% with the presumed death of three adults and three 9—month old juveniles during the same period. During the previous year, the temperature had also been cold, but range conditions were good. The herds did not noticeably decrease during the winter and few winter mortalities were foun d (Table 2). I t appears that cold weather, during periods when available foods are of low quality, causes high mortality rates i n south Texas pec-caries because of the excess energy drain through heat l o s s . This evidence i s substantiated by reports of very high mortality of peccaries during severe winters i n northern Mexico (Leopold, 1959), Arizona (Knipe, 1958), and Texas (Jennings and Harris, 1953). I have no estimate of winter mor-t a l i t y on the west Texas s i t e s , but I presume i t would be s i m i l a r to the south Texas lo s s . 4. Hunting Hunters k i l l n egligible numbers of peccaries on the King Ranch, and few on adjacent areas. I t i s impossible to assess outlaw hunting on the ranch, but i t occurs mainly i n the perimeter areas. My c o l l e c t i n g program removed about 3% of the population' per year i f an average density of one peccary per 100 acres i s assumed over the 200,000 acre d i v i s i o n . Hunting i s not a factor affecting peccaries i n the immediate area of the 160. Welder Refuge. However, several of the localized herds in the area of restricted habitat around Sinton have been k i l l e d off by hunters. Hunting on the Watson Ranch is restricted and few peccaries are k i l l e d there. On the Black Gap Wildlife Management Area, the hunters probably take 10 to 20°/) of the population. 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