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Spacing behavior of snowshoe hares in relation to their population dynamics Boutin, Stanley A. 1979

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SPACING  BEHAVIOR TO T H E I R  OF  SNOBSHOE  HARES  POPULATION  IN  RELATION  DYNAMICS  by  STANLEY B.Sc.(Hons.),  A..BOUTIN  The U n i v e r s i t y  of Alberta,  A THESIS IN PARTIAL FULFILMENT THE  REQUIREMENTS MASTER  FOR OF  THE  OF  D E G R E E OF  SCIENCE  in THE  FACULTY  OF  (Department  We  accept this to  THE  GSADUATE  o f Zoology)  thesis  the required  UNIVERSITY  OF  STUDIES  as conforming standard  BRITISH  December  COLUMBIA  1979  t a n l e y A. B o u t i n , 1979  1977  In p r e s e n t i n g t h i s t h e s i s  i n p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r  an advanced degree at the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I agree  that  the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s  thesis  f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s .  I t i s u n d e r s t o o d that c o p y i n g o r p u b l i c a t i o n  o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d without my written permission.  Department o f The U n i v e r s i t y o f B r i t i s h Columbia 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1W5  Date  flg<.  /(  I V<7  ABSTRACT The  importance  population  dynamics  from May 1978 t o J u l y a  9.29  ha  Numbers  breeding  densities  on  snowshoe  hare  1979. Two study s i t e s , each c o n s i s t i n g grid,  were  increasing  going  natality  behavior  was s t u d i e d i n the Kluane Lake, Yukon area  were  i n c r e a s e was a r e s u l t female)  spacing  live-trapping  animals.  per  of  from  8  over in  of  used t o c a p t u r e and t a g the  study  with  May  1978 t o 20 i n 1979. The  of higher than average  (12.25 young caught  r a t e s . Yearly j u v e n i l e and  adult  survival  r a t e s were e q u a l a t 20JL A  t o t a l o f 116 hares were equipped with r a d i o - t r a n s m i t t e r s  during the study. These were monitored t o determine  home  range  l o c a t i o n s and i n d i v i d u a l movements. Home ranges overlapped by a t least  30%  between  and  w i t h i n sexes throughout the year. Home  ranges averaged l a r g e r f o r males (4-8 ha) than females (3-5 h a ) . During p e r i o d s o f b i r t h , females c o n t r a c t e d the home  range  but  not s i g n i f i c a n t l y .  size  of  their  14 r a d i o - t a g g e d i n d i v i d u a l s  d i s p e r s e d during the study. They moved an average of 1045 m and were  from  a l l age and sex c l a s s e s with the e x c e p t i o n of a d u l t  males. To determine the importance of spacing b e h a v i o r on breeding females' home ranges and movements I removed a individuals The i n i t i a l first  from  a  second l i t t e r s .  group  of  much l a r g e r group o f radio-tagged animals.  removal was done 10 days b e f o r e  litters  small  the. b i r t h  o f the  and was then repeated 10 days before b i r t h of the Home ranges were monitored before and a f t e r each  removal and compared to a c o n t r o l a r e a . Females d i d not i n c r e a s e their  use  of  the removal  area  nor  was  i t colonized  by  individuals  from  beyond the r i n g o f radio-tagged animals.,This  suggests t h a t breeding female spacing  behavior.  Females  densities did shift  were  not  limited  by  use of t h e i r home range  a f t e r the removal by spending up t o 30% more time on the removal s i d e o f t h e i r range. T h i s suggests t h a t females use t h e i r  range  i n a manner t h a t avoids i n t e r a c t i o n . Adult  females  were  removed  from  during the l a t e breeding season to juvenile  movements  and  one of t h e study areas  assess  their  There  were  survival.  influence  no s i g n i f i c a n t  d i f f e r e n c e s i n these a s p e c t s between the manipulated control.,  However,  telemetry  showed  female home ranges overlapped l i t t l e September.  The  This  area and a  juvenile  and a d u l t  on the c o n t r o l area  during  movements t o c r e a t e t h i s s i t u a t i o n were done by  j u v e n i l e s a t a time b e f o r e tagged.  that  suggests  they  that  could  some  be  trapped  juveniles  may  or  radio-  leave t h e i r  p a r e n t s ' home ranges a t a time p r i o r t o which i s d e t e c t a b l e conventional  on  trapping  and  telemetry.  i n v e s t i g a t i o n i n t h i s area i s s t r e s s e d .  The  need  by  f o r further  iv  TABLE OF CONTENTS  ABSTRACT  --  i i  TABLE OF CONTENTS  ......iv  LIST OF FIGURES ............................................... v i LIST OF TABLES  ix  ACKNOWLEDGEMENTS  ,  .X  1. INTRODUCTION ................................................ 1 2. STUDY AREA  .....3  2.1 S i l v e r Creek C o n t r o l  .....6  2.2 Telemetry  7  3. MATERIALS AND METHODS 3.1.  8  Trapping..........................................8  3.2. Telemetry.,  9  4. DEMOGRAPHY  15  4.1. Results..........................................16 4.1-1. T r a p p a b i l i t y  16  4.1-2. Changes i n Numbers....................... 18 4.1-3. I n i t i a t i o n  of the Breeding Season........ 18  4.1-4. Number of Young  24  4.1-5. S u r v i v a l . ................................ 27 4.1- 6.  Juvenile  S u r v i v a l . . . . . . . . . . . . . . . . . . . . . . . . 34  4.2 D i s c u s s i o n . 4.2- 1.  Reproduction.  ...............40 ................44  4.2-2. Changes i n Numbers  45  4.2-3. S u r v i v a l  47  5. HOME RANGE SIZE AND SPATIAL ARRANGEMENT 5.1. Methods.  48 48  V  5.2. R e s u l t s  ...  56  5.2-1. Home Range S i z e . . . . . . . . . . . . . . . . . . . . . . . . . . 56  5.3.  5.2-2. Percentage Overlap.......................  61  5. 2-3.  68  Dispersal  Discussion.  ..7^  6. FEMALE SPACING BEHAVIOR .................................... 83 6.1. Methods  85  6.2. R e s u l t s  86  6.2-1. Removal One..............................86 6.2-1-1. Use o f t h e Removal Area....  86  6.2-1-2. Home Range Use..,,.....,  93  6.2-1-3. Number of Immigrants............ 95 6.2-2. R e s u l t s o f the Second Removal............ 97 6.3. D i s c u s s i o n .  .....103  7. EFFECT OF ADULT FEMALES ON JUVENILE MOVEMENTS AND SURVIVAL 111 7.1.  Methods..  7.2. R e s u l t s 7.2-1Survival  112 113 and D i s p e r s a l . . . . . . . . . . . . . . . . . . 113  7.2-2. Changes i n Home Range................... 113 7.3. D i s c u s s i o n . 8. SPACING BEHAVIOR LITERATURE CITED  ..............................127  AND SNOWSHOE HARE POPULATION DYNAMICS ...,130 ...................135  LIST OF FIGORES  F i g u r e 1. L o c a t i o n of study Figure  areas............................... 4  2. Changes in e r r o r polygon l e n g t h produced by  telemetry  system.  the  ............................11  F i g u r e 3. Minimum number a l i v e  (M.N.A.) estimates  for  S.C.C.and Telemetry during the study..................... F i g u r e 4. J o l l y p o p u l a t i o n  estimates  f o r S.C.C. and  Telemetry  d u r i n g the study....................... F i g u r e 5. Number of young trapped and  i n 1978  19  21  on S.C.C.  Telemetry.............................................25  F i g u r e 6. 1050,  Monthly s u r v i v a l r a t e s determined by t r a p p i n g a g r i d where no animals were r a d i o - t a g g e d ,  S.C.C. and  on  and  Telemetry, g r i d s where a large p o r t i o n of  animals were r a d i o - t a g g e d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  30  F i g u r e 7. Comparison of monthly s u r v i v a l r a t e s as determined by t r a p p i n g and  telemetry  (two  F i g u r e 8. Comparison of t e l e m e t r y  methods)................... 32  monthly s u r v i v a l  rates  on S.C.C. and Telemetry................................... 35 F i g u r e 9..Comparison of monthly s u r v i v a l r a t e s on S.C.C.  and  Telemetry as determined by t r a p p i n g r e s u l t s . . . . . . . . . . . . . . . 37 Figure  10. Method used to determine the e f f e c t of  system e r r o r on estimated Figure  home range s i z e . . . . . . . . . . . . . . . . . 50  11. R e l a t i o n s h i p between e r r o r polygon l e n g t h  overestimation Figure  telemetry  and  of home range s i z e . . . . . . . . . . . . . . . . . . . . . . . . . 53  12. Mean monthly home range s i z e s of  radio-tagged  hares i n 1978....... Figure  13.  1979  mean monthly home range s i z e s of  57 radio-tagged  vii  hares... Figure  59  14. Mean heme range s i z e s of females showing  smaller  range s i z e s during b i r t h v s . i n t e r b i r t h p e r i o d s . . . . . . . . . . . 62 Figure  15. Female 90% home ranges on S.C.C. showing  extensive Figure  o v e r l a p during t h e breeding season.............. 64  16. % o v e r l a p of female home ranges during  birth  vs. i n t e r b i r t h p e r i o d s . . .  66  F i g u r e 17. 90% heme ranges of males on S.C.C. showing high o v e r l a p d u r i n g t h e breeding season............ Figure  18. 90% home ranges of 3 males and 5 females on  S.C.C. showing high o v e r l a p between and w i t h i n Figure  .......69  sexes......71  19. 90% home ranges of males and females on the  study areas d u r i n g November 1978................  73  Figure 20. R e l a t i v e l o c a t i o n s o f female home ranges on Telemetry before the f i r s t  removal........................ 87  Figure 21. R e l a t i v e l o c a t i o n s o f female home ranges before and a f t e r the f i r s t  removal.................  ........91  Figure 22. R e l a t i v e l o c a t i o n s of female home ranges on Telemetry p r i o r to the second removal..................... 98 F i g u r e 23. R e l a t i v e l o c a t i o n s o f female home ranges before and a f t e r t h e secend removal............................. 101 F i g u r e 24. Home ranges o f j u v e n i l e snowshoe hares on Telemetry showing no change i n l o c a t i o n before vs.  a f t e r t h e removal of a d u l t females........  .....116  F i g u r e 25. Home ranges of j u v e n i l e hares on S.C.C, showing no change i n l o c a t i o n b e f o r e vs. a f t e r the removal of a d u l t females en Telemetry  ....................118  viii  Figure  26. R e l a t i v e  home ranges Figure  on S.C.C.  .............................121  27. R e l a t i v e l o c a t i o n s o f 4 a d u l t and 6 j u v e n i l e home  ranges Figure  l o c a t i o n s o f 5 a d u l t and 5 j u v e n i l e  on Telemetry.................................... 123  28. Home ranges of 5 a d u l t and 10 j u v e n i l e hares on  S.C.C. showing low overlap and September.  throughout  late  August 125  LIST OF TABLES  Table 1. T r a p p a b i l i t y of animals on Telemetry and S.C.C-....... 17 Table 2. S u r v i v a l r a t e s of j u v e n i l e s from f i r s t  trapping to  May 1..................... Table 3. Causes  39  of death o f r a d i o - t a g g e d hares................. 41  Table 4. S t a t u s , g r i d , timing o f movement, d i s t a n c e moved, and f i n a l f a t e o f hares d i s p e r s i n g d u r i n g the study...................................... 75 Table 5. Changes i n t h e p r o p o r t i o n o f l o c a t i o n s found in  the removal area f o l l o w i n g the f i r s t  removal....... 89  Table 6. Home range use by Telemetry females f o l l o w i n g the  first  removal  Table 7. Home range use by S.C.C. first  94 females a f t e r t h e  removal.........................................96  Table 8. Changes i n the p r o p o r t i o n o f l o c a t i o n s found i n the  removal area a f t e r the second removal.......  100  Table 9. Home range use by Telemetry females f o l l o w i n g the  second removal................................... 104  Table 10. Heme range use by S.C.C. the  females f o l l o w i n g  second removal..........  ...................105  Table 11. Fates o f r a d i o - t a g g e d j u v e n i l e s caught on S.C.C. and Telemetry a t l e a s t once before removal o f adult females.......... ............................. 114 Table 12. Number o f untagged animals captured on each g r i d a f t e r removal of a d u l t females on Telemetry.... 115  X  ACKNOWLEDGEMENTS I would s i n c e r e l y Sinclair*  l i k e t o thank my s u p e r v i s o r , Dr. A. B. E.  f o r h i s advice and  criticisms  along  with  help  throughout  the  study.. H i s  those of Dr. C h a r l e s J . Krebs helped t o  improve t h i s t h e s i s . I would l i k e to thank Dr. Krebs and Dr. J . N. M. Smith addition  f o r h e l p f u l suggestions throughout  I  would  like  to  thank  continuous and generous f i n a n c i a l  the f i e l d w o r k . . I n  a l l o f the above f o r t h e i r  support.  Thanks are due t o Kathy Hanson, V i v i a n H a i s t , Steve and e s p e c i a l l y  Scott G i l b e r t  f o r collecting  data.  Haist  me  Vivian  taught  portions  the fundamentals  o f the  of computer  programming and A l t o n Harestad provided the home range used  Millar,  programs  i n the study. S c o t t G i l b e r t and Ron Graf provided h e l p f u l  comments on the t h e s i s . I would e s p e c i a l l y l i k e Williams  for logistical  support  during  to  thank  the f i e l d  work.  r e c e i v e d support from a OBC t e a c h i n g a s s i s t a n t s h i p and an postgraduate  scholarship.  L o u i s e , who c o n t r i b u t e d study.  Finally,  unselfishly  I to  wish every  Andy I  NSERC  t o thank my wife, aspect  o f the  1  Is. INTRODUCTION  The  snowshoe hare  ( Lepus americanus ) i s known to e x h i b i t  r e g u l a r 10 year p o p u l a t i o n c y c l e s throughout much of ( Keith  1963  ).  Although  this  phenomenon  has  widespread i n t e r e s t , c a u s a l mechanisms are s t i l l to  date  attracted  Windberg  1978  ).  Few  behavior  of snowshoe hares, which  because  behavior  is  rapidly  studies is  ( Krebs and  Myers 1974;  There are two snowshoe  hare  have  of  a  d e n s i t i e s without  as an  regulation  are  capable  of  species  )..  formulated  by C h i t t y ( 1960 and  contends  of l i m i t i n g t h e i r own  so." hares  densities  In  contrast,  are  determined  by  that  which  accidents  Keith  "...incapable  ),  population  e i t h e r d e s t r o y i n g the food resources to  snowshoe  below  important  major hypotheses which attempt t o e x p l a i n the  them from doing  that  the  interesting  are adapted, or depending on enemies or c l i m a t i c  to prevent  1974;  examined  number  Watson and Moss 1970  c y c l e . The f i r s t ,  species  Keith  particularly  attempts t o e x p l a i n a l l s m a l l mammal c y c l e s "... a l l  (  being recognized  component of the p o p u l a t i o n dynamics  states  Work  has been p r i m a r i l y concerned with the r e l a t i o n of hare  and  they  range  unknown.  demographic changes to food supply and p r e d a t i o n Keith  its  ( 1974 of  self-  available  s u p p l i e s . " C h i t t y f e e l s t h a t a g g r e s s i v e spacing behavior  )  food  a c t s to  l i m i t numbers below t h a t d i c t a t e d by food s u p p l i e s whereas K e i t h ( 1974  )  feels  behavior  determined  directly  predation.  Examining  movements, s u r v i v a l ,  by the and  is a  unimportant  combination effect  of  reproduction  and  of  hare numbers are  food  supply  and  spacing behavior on hare then,  should  help  to  2  decide  between  examined  these  snowshoe  particularly  hare  that  j u v e n i l e s because  two  of  hypotheses.  movements juveniles  and  and  K e i t h and Windberg  In  this  study I have  spacing  adult  behavior,  females.  I chose  ( 1978 ) found that changes  i n t h e i r s u r v i v a l r a t e s were most i n f l u e n t i a l i n o v e r a l l changes i n hare numbers. Females were chosen because I f e l t be  most  influential  would  i n determining o v e r a l l r e p r o d u c t i v e r a t e s  which were a l s o found t o change with the c y c l e 1979  they  ( Cary and  Keith  ) . I was concerned with answering the f o l l o w i n g q u e s t i o n s : 1.  What i s the s p a t i a l arrangement  what does t h i s  arrangement  o f hare home ranges and  suggest  about  snowshoe  hare  s o c i a l organization? 2.  Is  the  presence  of  adjacent  females  important  in  determining the use and l o c a t i o n o f a female's home range? 3.  Do  adult  females  influence  juvenile  movements  and  survival? Answers  to  the  f i r s t q u e s t i o n w i l l give s o m e . i n d i c a t i o n as t o  how hares d i v i d e up resources such as food and space. The second question i s aimed at determining whether female spacing behavior i s i n f l u e n t i a l enough t o prevent some i n d i v i d u a l s from breeding. The f i n a l behavior  guestion can  i s an  affect  populations  and  to  determine  i f spacing  j u v e n i l e s u r v i v a l and thus be important i n  hare p o p u l a t i o n dynamics. hare  attempt  To answer these q u e s t i o n s I  monitored  c a r r i e d out experiments from May 1978 t o  July  1979. The demography of these p o p u l a t i o n s  the  experiments w i l l be p r o v i d e d . F i n a l l y , answers to the above  q u e s t i o n s w i l l be d i s c u s s e d i n t h e context dynamics.  of  and  hare  results  of  population  3  2. STUDY AREA  The  two  main study areas, S i l v e r Creek C o n t r o l  and Telemetry, were l o c a t e d near Kluane Lake, 240 of  Whitehorse,  Yukon  separated by 700  Territory  (  Fig.  1)  ( S.C.C..)  km  northwest  . The s i t e s were  meters of continuous f o r e s t and S i l v e r Creek, a  s m a l l stream t h a t blocked hare movement between s i t e s from to  June  mid-September.. Another study area, S i l v e r Creek Removal  l o c a t e d between the two involved  with  main  sites.  It  was  only  was  indirectly  t h i s study. Animals were caught and removed from  t h i s area, thus c r e a t i n g a block of unoccupied h a b i t a t . Topography  i n the Kluane area i s h i g h l y v a r i a b l e . The study  s i t e s were l o c a t e d on l e v e l ground with shallow, o l d creek providing  the  only  relief.  beds  To the north of Telemetry and the  south of S.C.C.  the l a n d  becomes  more  rugged  and  gains  in  elevation.  The  area surrounding each s i t e w i l l be d e s c r i b e d i n  more d e t a i l  later.  The c l i m a t e i s c h a r a c t e r i z e d by long w i n t e r s with l i g h t but p e r s i s t e n t snow cover from November t o l a t e were  never  more  April.  of  25°C  in  winter  are and  i n summer. The sun i s above the h o r i z o n f o r 4-6  hrs. d u r i n g November-February The f r o s t  depths  than 40 cm d u r i n g the study. Temperatures  v a r i a b l e throughout the year with lows of -50°C highs  Snow  and  18-21  h r s . i n June and J u l y .  f r e e p e r i o d runs from e a r l y June to l a t e  August.  New  l e a v e s and herbs begin to appear i n s p r i n g from mid t o l a t e  Way,  and the growing season ends  hares  have  growing  in  late  August.  This  means  herbaceous and woody m a t e r i a l a v a i l a b l e t o  them f o r roughly f o u r months each year.  4  F i g u r e 1. L o c a t i o n of study areas. S . C . C . - S i l v e r Creek C o n t r o l S.C.H.-Silver Creek Removal Tel.-Telemetry 1-7 - Tower L o c a t i o n s  5  6  The winter of 1978-79 was February  on  u n u s u a l l y harsh with the  record o c c u r r i n g . Temperatures never  30°C f o r the e n t i r e month. T h i s was relatively  early spring. boreal  forest.  It  is  t o the c l o s e d spruce community as c l a s s i f i e d by Douglas  (1974). White spruce  (Picea qlauca)  i s the dominant t r e e s p e c i e s  with v a r i o u s amounts of willow j S a l i x (Shepherdia  canadensis)  making  up  spp. the  )  Lupinus  arcticus  provide  much  and  buffaloberry  understory.  (ft rc t o s t ap h v 1 o s u v a - u r s i ) . Dryas drummpndii, and  rose above  f o l l o w e d by a mild March and  Vegetation i n the area i s northern similar  coldest  of  Bearberry  Hedysarum  boreale  the herbaceous ground  cover. P o t e n t i a l competitors of the snowshoe hare are moose i A l e e s alces) and  Arctic  ground  Mammalian  predators  squirrels  (Spermpphilus  present are lynx ijvynx canadensis) , coyote  (Canis l a t r a n s ) , wolf  (Canis lupus),, weasel  (Mustela f r e n a t a ) and  marten ^Marteo  owls  (Bubo  V i r g i n i a n u s ), goshawks  )  are  the  (Mustela rixpsa)_  americana).  Great  Swainson's  hawks  major avian predators*. The  g e n e r a l d e s c r i p t i o n of the study area. I w i l l now two  and  horned  (Accipiter g e n t i l i s ), red-  t a i l e d hawks (Buteo jamaicensis ) and swainsoni  undulatus).  (Buteo  above g i v e s a describe  the  s p e c i f i c s i t e s i n more d e t a i l .  2. 1. S i l v e r Creek C o n t r o l  S.C.C.  was  located  on  e n t i r e area i s covered by mature  an o l d rocky stream white  spruce  outwash.  with  a  The  sparse  7  understory  of  willow and b u f f a l o b e r r y . The Alaska Highway runs  along the southern edge of the area and c r e a t e s an open space of 250  meters between  beyond.  Very  the  study  area  and  suitable  hare  cover  few animals are known t o have c r o s s e d t h i s  strip.  The remaining t h r e e s i d e s of S.C.C.. have h a b i t a t s i m i l a r to the site i t s e l f .  S i l v e r Creek runs 300-350 meters north of the  However, the area up t o 100 meters from the open  spruce  canopy  and  a  thicker  creek  understory  has  a  grid. more  of willow and  b u f f a l o b e r r y than on the study area.  2-.2^. Telemetry  Telemetry i s bordered on the south by S i l v e r Creek and  the  north by a l i g h t l y used road. The road does not act as a b a r r i e r to movements and animals pass f r e e l y from one s i d e t o the o t h e r . The  e a s t and west s i d e s of Telemetry are bordered by continuous  f o r e s t . V e g e t a t i o n on the a c t u a l study  area  is  more  variable  than on S.C.C. . The north h a l f i s covered by mature spruce with a  sparse  understory  understory while the southern h a l f has a t h i c k willow and open spruce canopy.  8  3. MATERIALS AND METHODS  3.1.  Trapping  Each study trapping  area c o n s i s t e d o f a 300 x 300  grid.  meter  (9.29 ha)  One hundred s t a t i o n s were arranged i n a 10 x 10  p a t t e r n with 30 meters tetween s t a t i o n s . F i f t y double door  live  t r a p s were placed a t a l t e r n a t e s t a t i o n s on each g r i d . I f runways were  present  nearby,  traps  were  placed  b a i t e d with a l f a l f a cubes throughout June  of  on them. Traps were  the study. In l a t e May and  1979 t h i s was supplemented with a p p l e s . During w i n t e r ,  most t r a p s were s e t with a s i n g l e door open and  the b a i t  well  behind the t r e a d l e . Traps  were s e t f o r two c o n s e c u t i v e n i g h t s and checked  morning* During the summer they were a l s o checked of t h e f i r s t and  day.  When not i n use t r a p s were  each  i n the evening  left  in  position  l o c k e d open. From May through September 1978 t r a p s were s e t  on both g r i d s once a week. They October,  also  s e t once  i n mid-  twice i n l a t e November, weekly i n March 1979, twice i n  late April, also  were  and then weekly u n t i l the end of J u l y . ,  trapped  once  S.C.C.  was  i n each o f August, September, and October,  1977. The l o c a t i o n , t a g number, sex, r e p r o d u c t i v e c o n d i t i o n * right  hind  foot  length was recorded f o r each  Newly captured animals were ear-tagged tag.  Reproductive  condition  of  f u r indicated  animal captured.  a  numbered  females was determined  s i z e and appearance of n i p p l e s . Medium matted  with  or  and  large  metal by the  nipples  with  that the i n d i v i d u a l was n u r s i n g a l i t t e r *  9  Pregnant females c l o s e to term c o u l d Males with t e s t e s i n s c r o t a l breeding  sacs  be determined by p a l p a t i o n . were  considered  to  be  in  conditon.  3. 2. Telemetry  In mid-May of 1978, hares on both study areas were equipped with  radio  transmitters  (Wildlife  Materials  t r a n s m i t t e r produced a p u l s i n g s i g n a l at within and  the  specific  around the animal's neck with  Radios  were  located  directional  yagi  antenna.. Strongest  with  when the antenna was pointed i n i t i a l stages,  during  animals  were  a  receiver  rest  frequency  strapping. attached  s i g n a l reception  l a t e May  and  located  by  early means  June of  a  small  the study, the m a j o r i t y  radioportable  s i g n a l strength For  grid  and  their  relative  was the  of animals were l o c a t e d by use  of permanent towers. Two or more of these were e s t a b l i s h e d each  a  occurred  1978,  u n t i l I was c e r t a i n of the animal's l o c a t i o n .  of  to  d i r e c t l y at the t r a n s m i t t e r . In the  handheld antenna. The d i r e c t i o n of s t r o n g e s t followed  Each  range of 150.8 t o 151.8 Mhz. Each u n i t weighed 30 g  was attached  tagged  a  Inc.).  near  l o c a t i o n s are shown i n F i g . 1.  Towers 1, 2, 4, and 5 were e s t a b l i s h e d i n mid-June 1978. Tower 3 was e s t a b l i s h e d i n l a t e August 1978 while 6 and 7 in  May  and  4 were f i v e meters  placed  1979. Towers 1 and 2 were 12 meters high  on  high  c o u l d be detected permanent towers.  high.  The  latter  two,  were  erected  while 6, 7, 3, however,  were  p o i n t s of land to i n c r e a s e t h e i r range. Radios at a distance  of  up  to  two  km  with  these  10  Each  tower supported a d i r e c t i o n a l y a g i antenna that  be r o t a t e d  from ground l e v e l . The d i r e c t i o n of the  read  a  off  animals  protractor  were  strongest  antenna  by  triangulation.  The  bearing  transmitter's  technigue  is  of  f o r each t r a n s m i t t e r was determined from two  towers. The p o i n t at which these two bearings c r o s s e d the  was  a t the base. P o s i t i o n s of r a d i o - t a g g e d  determined  signal  could  location.  not  actually  The a  location  point  but  indicated  of a r a d i o by t h i s a  polygon  shaped  p r o b a b i l i t y a r e a . The s i z e and shape of the polygon i s dependent upon  the  l o c a t i o n of the r a d i o r e l a t i v e t o the l o c a t i n g  (Heezen and T e s t e r 1967). T h i s i s due mechanical  error  exists  in  to  the  determining  fact  the  placed  radios  at  known  each a t o t a l of 20 times confidence  this  some of the  error  from  each  of  the  towers.  The  95%  i n t e r v a l s around the means were determined and found  In  other  be  the  error  of  the  words a 3° band c e n t e r e d around the recorded  bearing would c o n t a i n the t r u e bearing 95% of the time. I f a band  is  drawn  from  polygon  changes  (Heezen  and  Tester  1967).  i n s i z e and shape depending on where the  l i n e s meet r e l a t i v e t o the error  3°  each of two towers as shown i n F i g . 2 the  l i n e s meet t o form an e r r o r polygon This  I  l o c a t i o n s and recorded the bearing t o  to be near 3° each time. I took t h i s t o system.  that  bearing  s t r o n g e s t r a d i o s i g n a l . To determine the s i z e of  towers  towers.  For  example,  compare  the  polygons a t p o i n t s A and B. That a t p o s i t i o n A has a much  s h o r t e r l e n g t h r e l a t i v e t o t h a t at p o s i t i o n B. During combinations  the that  study,  radios  minimized  Radio l o c a t i o n s f a l l i n g i n  an  were  the area  located  from  tower  l e n g t h of the e r r o r polygon. where  the  error  polygon  11  Figure 2 . Changes i n e r r o r polygon length (EPL) produced by a t e l e m e t r y system having a 3° e r r o r (3° c o n f i d e n c e interval C.I.). Notice EPL changes with i t s p o s i t i o n r e l a t i v e t o the l o c a t i n g towers (A vs. B).  .  3°CI  - - - E P L \  1  B A S E L I N E  2  13  l e n g t h was  g r e a t e r than 150 meters were d i s r e g a r d e d .  When by two  possible,  each t r a n s m i t t e r was  people, one a t each  instances,  a  single  of  two  located  towers.  synchronously  However,  in  person l o c a t e d a l l o f the t r a n s m i t t e r s i n  the area b e f o r e moving to the next tower t o repeat the This  Rapid produced  and second  variations  in  bearings on each animal.  transmitter  signal  strength  when an animal changes i t s o r i e n t a t i o n  r e c e i v i n g antenna. animal  was  active  or  not.  Individuals  with a handheld  are  r e l a t i v e to the  These changes were used t o determine  a c t i v i t y or changes i n l o c a t i o n over 2-3  the  process.  meant t h a t a maximum of 15 minutes could occur between the  t a k i n g of the f i r s t  the  most  that  whether showed no  days were then  located  antenna t o see whether the animal was dead or i f  transmitter  had  fallen  off.  This  was a l s o done f o r any  animals making unusual movements. T r a n s m i t t e r s found i n t h i s were examined t o determine portion  of  the  animal  what had still  way  happened t o the owner. I f  remained  the proximate cause o f  death c o u l d o f t e n be determined. I f only the r a d i o was found the s t r a p p i n g was was  dead.  s t a t u s was  still  i n t a c t I c o u l d be sure t h a t  and  freguencies  were  weight of 500  throughout late  r a d i o - t a g g e d . , No  were  the  the  taken  study.  July  of  animals  at  These 1978  various will  the  be  first  were tagged below a  g.  The above p r o v i d e s a d e s c r i p t i o n of during  animal  recorded as unknown.  s p e c i f i e d where p e r t i n e n t . . In juveniles  the  and  When the s t r a p p i n g was m i s s i n g or broken the owner's  L o c a t i o n s of radio-tagged animals times  a  general  methods  used  study. More s p e c i f i c technigues w i l l be provided at  the beginning of r e l e v a n t  sections.  15  ib. DEMOGRAPHY  T h i s s e c t i o n examines the demography of hare p o p u l a t i o n s on Telemetry  and S.C.C. . Trapping estimates of p o p u l a t i o n  will  provided  be  along with s u r v i v a l r a t e s from  both t r a p p i n g  and t e l e m e t r y t e c h n i q u e s . The number of young produced area  will  density  in  each  a l s o be estimated. F i n a l l y , the values obtained  will  be compared to those of previous s t u d i e s . I used two They  were:  mark-recapture  complete  s t o c h a s t i c model  techniques t o  enumeration  ( Jolly  1965  estimate  ( Krebs 1966  ) . As the name  numbers.  ) and the  suggests  Jolly  complete  enumeration i n v o l v e s c a p t u r i n g a l l of the animals present d u r i n g each  trapping  session.  The  capture data which i s used t o survival into  a  and model  estimation animals in  the  Jolly  method i s based  generate  on m u l t i p l e  probability  values  of  p o p u l a t i o n growth. These i n t u r n are i n c o r p o r a t e d which  produces  technigues  i n v o l v e d . The population  population  estimates..  Both  are s e n s i t i v e to the t r a p p a b i l i t y of the Jolly  have  method assumes that a l l egual  probability  of  individuals  capture  while  complete enumeration i s e f f e c t i v e only when the t r a p p a b i l i t y animals i s g r e a t e r than 50% To determine trappability for  ( H i l b o r n et a l . 1976  whether these c r i t e r i a were met  ). I measured the  of the p o p u l a t i o n a t d i f f e r e n t times.  each animal was  c a l c u l a t e d by the  Trappability  formula:  ( number of captures during time t  of  ) -2  ( maximum p o t e n t i a l number of captures during time  ) - 2  16  An example would be as f o l l o w s . Over s i x time  t an animal was f i r s t  4.  The  maximum  Subtracting f i r s t  sessions  number of captures over  potential  number  of  and l a s t captures g i v e s a  time  captures  was  trappability  t 6.  value  of  2/4  a  mean f o r the p o p u l a t i o n . S u b t r a c t i n g 2 from the numerator  or 50%. Values f o r each animal were then averaged t o g i v e  denominator twice  in  caught i n s e s s i o n numbers 1 and then  again i n 3, 4, and 5. The t o t a l was  trapping  excludes animals t h a t  ( H i l b o r n et a l . 1976  are  captured  only  and  once  or  ).  4.1. R e s u l t s  4. 1-1.  Trappability  Table  1  shows t h a t mean t r a p p a b i l i t y was  Oct. 78 - Feb. 79 and May-June 1979 Values  though,  on  l e s s than 50% i n  Silver  Creek  Control*  were never l e s s than 40%. In t h r e e of f i v e  p e r i o d s examined, animals were l e s s c a t c h a b l e on S.C.C. T e l e m e t r y . . T r a p p a b i l i t y v a r i e d between sexes. Major were  apparent  in  1978 on S . C . C 1979 was  on  March-June  1979  time  than on  differences  on Telemetry and Aug.-Sept.  Males were h i g h l y t r a p p a b l e i n March  and  April  both g r i d s . Average t r a p p a b i l i t y over the e n t i r e study  59% on Telemetry and 53% on Hilborn  et  al.(1976)  S.C.C  found  that  complete  enumeration  underestimated p o p u l a t i o n s i z e by at l e a s t 20% when t r a p p a b i l i t y dropped  below  50%.  enumeration  estimates  differences  between  Conseguently will  be  estimates  both  provided may  Jolly for  and  complete  comparison.  Any  i n d i c a t e b i a s e s that can be  17  TABLE 1  T r a p p a b i l i t y o f animals on Telemetry and S.C.C...All values are expressed as percentages. Sample s i z e s are i n b r a c k e t s .  PERIOD  S• C• Cm  TELEMETRY  NO.  TRAPPING SESSIONS  M  MEAN  MEAN  MayJuly/78  67. 7 (7)  AugSept/78  55. 2 (16) 53.8(13) 54.6  40.2 (11) 66. 2(18) 56.3  OctFeb /79  62. 9 (18) 62.5(10) 62. 8  48.3 (11) 44.4(14) 46.1  MarApr /79  86.5 (13) 53.0(11) 71.2  85.2 (9)  MayJune/7 9  69. 2 (13) 41.7(14) 55.0  39.4 (11) 48.3(10) 43.7  May/78July/79  28  69.6(6)  68.6  74.0 (3)  40.0 (6)  70.4 (9)  51.0  77.8  59.3 (36) 59.0 (38) 59.6 5 2 . 2 ( 2 6 ) 54.2(26) 53.5  18  corrected for.  4.1-2. Changes i n Numbers  Fig.  3  shows , t h a t  M.N.A.  ( minimum  number  alive )  estimates were s i m i l a r f o r the two study areas. Numbers began t o increase  i n 1978 with  t h e recruitment o f j u v e n i l e s i n t o t h e  p o p u l a t i o n . T h i s occurred i n e a r l y J u l y on both g r i d s but a t a slower  initial  rate  on  Silver  Creek  C o n t r o l . . A f t e r numbers  peaked i n September there was a moderate subsequent  recovery  i n November.  p o p u l a t i o n had dropped  to half  Immigration,  by  primarily  In that  females,  drop  i n October  early  March  1979 the  present  i n September.  i n early  May, caused an  i n c r e a s e i n e s t i m a t e s . Estimates i n June were 1.9 and 2.6 those of one year e a r l i e r on S.C.C. The  M.N.A.  estimate  and  times  and Telemetry  respectively.  f o r August 1977 on S.C.C.  was 4. Fig.,4  shows t h a t J o l l y p o p u l a t i o n estimates followed a p a t t e r n s i m i l a r t o M.N.A. increasing  but are up t o 20 % h i g h e r . Hare during  1977-1979.  Both  numbers  grids  then,  followed  were  similar  p a t t e r n s o f d e n s i t y change.  4.1-3. I n i t i a t i o n of Breeding  Season  Trapping d i d not begin e a r l y enough i n 1978 to when  males  came  into  breeding  condition.  A l l adult  captured between May 1 and August 7, 1978 were s c r o t a l . i n non-breeding  c o n d i t i o n a f t e r mid-August.  determine males  A l l were  19  F i g u r e 3. Minimum number a l i v e (M.N.A.) Tel. during the study.  estimates  for  S.C.C.  and  20  21  F i g u r e 4. J o l l y p o p u l a t i o n estimates study.  f o r S.C.C.  and  Tel.  during  the  22  100  70  j  2  1  1 MAY  J  S 1978  N  FEB  A  J 1979  23  In  1979, f o u r of 15 males captured during  scrotalthe  Two  weeks  t h r e e abdominal  March  6-8  were  l a t e r 20 of 23 were c l a s s e d as s c r o t a l animals continued to  be  so  even  and  in  late  June, s u g g e s t i n g t h a t they d i d not breed. Thus h a l f of the males were i n breeding c o n d i t i o n by March 15,1979. The f i r s t 3,  and  four  lactating was  litters of  six  of 1978 S.C.C.  28 were  37  days  final  female  when i t was next captured on June 12. M l  females  August  around  The  by June 3. Thus a  ( S e v e r a i d 1942  dates i n 1978  caught  f o u r days l a t e r .  on Telemetry were l a c t a t i n g of  females  25 and June  on May  while a f i f t h was  lactating  were born between May  gestation  ) would put f i r s t  A p r i l 23. F i n a l l i t t e r s  period  l i t t e r conception  were born i n  and females had ceased l a c t a t i n g permanently  early  by September  23. In  1979  first  litters  were born around May  19. Two  females  removed from Telemetry and p l a c e d i n 3 x 9 m pens gave b i r t h this  time.  Twc  trapped on May that  they  S.C.C.  17-18  were  during  pregnant  females which died while being  had embryos weighing over 50  g  at live-  indicating  c l o s e to term. Four of e i g h t females caught on the  week  of  May  21-27  were  lactating.  The  remaining f o u r were l a c t a t i n g the next week. On the Telemtry g r i d two females had given b i r t h during the week  of  May  14-20,  1979. Two  weeks l a t e r a l l but two  captured were l a c t a t i n g . I t appeared,  through  that these two animals d i d not produce a f i r s t To  summarize,  first  18 and June 3. T h i s p l a c e s April  11, almost two  litters first  later  females  trapping,  litter.  i n 1979  were born between  litter  conception  weeks e a r l i e r than i n 1978..  dates  May at  24  4. 1-4.  Number of Young  Meslow and K e i t h highly  ( 1968  synchronized.  ) found that b i r t h s of l i t t e r s were  This,  along  with  immediate  postpartum  mating, served t o produce d i s t i n c t l i t t e r groups d i s t i n g u i s h a b l e by weight. Three l i t t e r s were born on both Telemetry and in  S.C.C.  1978. F i r s t t r a p p i n g dates of i n d i v i d u a l s from r e s p e c t i v e  l i t t e r s were June Second  and  22, J u l y  third  19,  litter  and  August  18  on  Telemetry.  young were captured 10 days l a t e r i n  each case on S.C.C. Young s t a r t e d t o enter t r a p s around roughly 25 days of age and a t a weight of 300-400 g. Adult females not  caught  often  produced t h r e e  enough  to determine whether each i n d i v i d u a l  litters*  The number of young caught from each l i t t e r is  shown  in  Fig.5.  Numbers  before Sept. 30. A f t e r enough litter on  to  place  this  newly  grid  except  first  caught  time  trapping  between  first  not  frequent  for  litter  two  were  and  second  similar  where the number was produced  l i t t e r s may  s i z e s i n the l a t t e r as found  by  rates  similar  in  number  be e x p l a i n e d by Cary  and  Keith  produced  a  ) found l i t t e r  two  sizes  f o r the two. The t o t a l number of  young trapped to September 30 was 49 This  ( 1979  50%  as many young as  ) . T h i s cannot e x p l a i n the d i f f e r e n c e between l i t t e r s  pregnancy  S*C.C.  grid  tagged j u v e n i l e s i n t o t h e i r r e s p e c t i v e  and t h r e e however, as Cary and K e i t h and  was  and t h i r d l i t t e r s combined. The d i f f e r e n c e  larger l i t t e r ( 1979  each  are determined from young caught  higher on Telemetry. The second l i t t e r the  and  groups. Numbers of young caught per l i t t e r  each  were  on  Telemetry  juvenile/female  ratio  and of  37 12.25  on on  25  F i g u r e 5. Number of young trapped i n 1978 on S.C.C.. and Telemetry. N o t i c e t h a t over h a l f of t h e animals were from the second litter.  s.c.c. 4 OJ  TEL.  c/> 3 0_ LU  <  2 0.  104  LITTER  NO.  n  27  as compared to 6*3 on S.C.C.  Telemetry  To summarize, over h a l f of the j u v e n i l e s captured were from the second  litter.  Twice  female on the Telemetry  4.1-5  many  as  juveniles  were  caught  per  g r i d as on S.C.C.  Survival  S u r v i v a l e s t i m a t e s were c a l c u l a t e d i n three d i f f e r e n t  ways.  They were: 1.  Trapping  method  -  t h i s method uses r e c a p t u r e data to  c a l c u l a t e the r a t i o of (number of animals r e l e a s e d at time t and known t o be a l i v e a t t + 1)  (number of animals r e l e a s e d a t time t) 2. Simple t e l e m e t r y - T h i s technique r e c o r d s the number  of  animals  by  known  to  be  alive  telemetry and then records how alive  at  time  t+1.  at  time t , as determined  many  of  these  are  still  I t i s s i m i l a r t o the t r a p p i n g method  except that a radio-tagged animal l o c a t e d and considered t o be a l i v e i s e g u i v a l e n t t o an animal  being  released  after  trapping. 3.  Trent  and  Eongstad  ( 1974 )  -  This  technique uses  t e l e m e t r y t o c a l c u l a t e a mean d a i l y s u r v i v a l r a t e  (Sd)  by  the formula: Sd = ( x-y )/x where: x = to  number of r a d i o - h a r e days 1  radio-tagged  hare  ( 1 r a d i o - h a r e day i s equal  i n the f i e l d f o r 1 day ) i n time  28  period t. y =  number of m o r t a l i t i e s i n time period t . S u r v i v a l over  n days can be determined by can  be  placed  ( Sd )  and  confidence  on the e s t i m a t e by f o l l o w i n g the method of  Trent and Hongstad  ( 1974  ).  Telemetry i s u s e f u l as a method of measuring if  s t u d i e s have attemped t o determine  1979;  Boag et a l . 1973  overwinter vs.  weight  ).  loss  Brand of  et  hares  a l . ( 1975 was  at  a  greater  rate  than untagged  s u f f e r higher m o r t a l i t y r a t e s . T h i s c o u l d l o o k i n g at weight To t e s t  )  in  that  collared  may  still  lose  i n d i v i d u a l s and not  be  detected  thus by  l o s s e s of s u r v i v o r s .  f o r equal s u r v i v a l I compared the t r a p p i n g s u r v i v a l  r a d i o - t a g g e d animals with those t h a t were not tagged. Because majority  untagged  of  the  animals  were radio-tagged at some p o i n t  animals.  large  I overcame t h i s by examining  sample  calculated  these i n d i v i d u a l s were s t i l l  1,  Trapping untagged  Telemetry  1  and  1. These were d i v i d e d a c c o r d i n g t o whether or not they  had r e c e i v e d r a d i o c o l l a r s . F i n a l l y I  collars  of  the s u r v i v a l of  i n d i v i d u a l s captured f o r the f i r s t time between J u l y  December  for  showed  similar  d u r i n g the study i t was d i f f i c u l t to o b t a i n a  all  individuals.  u n c o l l a r e d hares. However, sample s i z e s were s m a l l . As w e l l ,  weight  the  only  i f t h i s i s t r u e ( Herzog  radio-tagged animals which d i e over the winter  of  survival  r a d i o - t a g g e d animals s u r v i v e as w e l l as untagged  Tew  limits  survival  a l i v e May  how  of  1979.  of r a d i o - t a g g e d animals was  higher than  i n d i v i d u a l s . None of 25 animals on S.C.C.  s u r v i v e d to May  many  without  1. F i v e of 21 with c o l l a r s s u r v i v e d . On  3 of 43 without c o l l a r s s u r v i v e d whereas 5 of 22  with  29  collars  survived.  Although  t h i s suggests that c o l l a r s d i d not  increase mortality rates, i t Animals  that  received  captured r e g u l a r l y on animals  in  the  is  not  radios the  were  grid.  sample  completely most  As  a  satisfactory.  often  result  those most  being  untagged  were captured only once or twice, thus  b i a s i n g the sample toward i n d i v i d u a l s with high r a t e s  of  early  disappearance. To t e s t f u r t h e r whether radio-tagged and untagged hares similar  survival  rates  I  another  trapping grid  with  (1050)  was  two  located  examined s u r v i v a l of i n d i v i d u a l s no km  radio-tagged east  summer  Animals  and  similarly  greater  most  of  than  Fig. 7  those  compares  merely  Trapping using  the  was  always egual  l i v e - t r a p p e d on 1050. rates  to  This too, comparable  Animals  from  by the t h r e e  both  grids  were  and a d u l t s were pooled s i n c e there were no  differences in  telemetry.  1979  telemetry  and  survival  between  the  two  groups.  e s t i m a t e s were always lower than e i t h e r of the methods  telemetry June  S.C.C.  s u r v i v a l r a t e s as determined  described.  Juveniles  significant  to  animals.  methods p r e v i o u s l y combined.  grid  the winter. F i g . 6 shows t h a t s u r v i v a l o f  suggests t h a t r a d i o - t a g g e d hares had s u r v i v a l to untagged  This  were trapped every three weeks throughout  radio-tagged hares on S.C.C.. and Telemetry or  hares.  on  of the main study areas. I t  c o n s i s t e d of a t r a p p i n g g r i d arranged Telemetry*  had  The  estimates ( X; 2  methods  sake of b r e v i t y ,  difference was  significant  P<.05 ). were only  between  Survival  the  i n Nov.  trapping - Feb.  estimates  by  and  and May the  two  very s i m i l a r . Because of t h i s , f o r the the  simple  telemetry  method  will  be  30  Monthly survival rates determined by t r a p p i n g on 1050, a g r i d where no animals were r a d i o - t a g g e d , and S.C.C. and Telemetry, grids where a l a r g e p o r t i o n o f animals were radio-tagged. Notice s u r v i v a l rates on S.C.C. and Telemetry were egual t o or higher than those on 1050. Sample s i z e s are placed above each column.  31  S U R VI V AL co  H  h  RATE (0  03  I  >  (0 -J 00  CO  CO . I  o  CO  z  o <  ro  o  I  n m  o  CO  CO  CO  i  H  m  03  2  b b  32  F i g u r e 7. Comparison of monthly s u r v i v a l r a t e s as determined by trapping and telemetry (two methods). G r i d s have been combined. Notice t h a t t r a p p i n g r a t e s are much lower than telemetry estimates i n Nov.-Feb. and May-June 1979. Sample sizes are found at the top of each column. Trent and Rongstad (1974) sample s i z e s represent r a d i o - h a r e days.  34  discussed  from now  Fig. similar  on.  8 shows t h a t for  the  monthly telemetry  two  grids  throughout  lowest i n March - A p r i l 1979  and  but  not  the  differences  l o s s e s were recorded dropped the  by  10%.  were until  I t continued  Fig. 9  averaged 15%  shows  that  To constant  which  time  to remain near 90% to  P>.05 ) . No survival  per month f o r  telemetry  survival  trapping s u r v i v a l estimates  control  than  on  Telemetry.  The  i n May-June of each year. fairly  with  March - A p r i l  1979.  levels  slightly  estimates by t r a p p i n g and  May  d i f f e r e n c e i n May  - June 1979 - June 1979  t r a p p i n g s u r v i v a l on S. C.C.  4.1-6. J u v e n i l e  number  and  was  in  telemetry  17% and due  d i f f e r e d i n Nov.  24% r e s p e c t i v e l y .  The  mainly t o an unusually  low  Survival  of workers have concluded that j u v e n i l e s u r v i v a l  and  Evans 1940a ) and  ( K e i t h and  Windberg 1978;  small mammal c y c l e s i n general  ). Table 2 shows j u v e n i l e s u r v i v a l r a t e s to  -  at t h i s time.  be important i n hare c y c l e s  Myers 1974  lower  by  may  trapping  2  the study was  1978  A  at  ( X;  1978  summarize, monthly s u r v i v a l during  Survival Feb.  J u l y -August  significant  monthly  l a r g e s t d i f f e r e n c e s occurred  in  contrast  lower on S.C.C.  the study. Rates were  highest  September  d u r a t i o n of the study. In  rates  s u r v i v a l estimates were  May  1.  The  they were born i n . S u r v i v a l o f  twice  that  of  the  ( Krebs from  animals are grouped according  litter  second.  No  first  third  O v e r a l l j u v e n i l e s u r v i v a l from f i r s t  litter  litter  Green  young  and  first to  young  the was  survived.  t r a p p i n g t o s p r i n g was  less  35  F i g u r e 8. Comparison of telemetry monthly s u r v i v a l r a t e s on S.C.C. and Telemetry. Note t h e . s l i g h t l y lower r a t e s during w i n t e r . Sample s i z e s are placed above each column..  36  SURVIVAL I  I  CO  Ol  I  RATE 0)  I  oo  to  o  I  >  oo  CO  -J  to  o  00 CO  I  o  —i  CO  m o  r b  o < I  Tl  CO  m 03  CO  CO  03  -J  CO  CO  I  urn  37  F i g u r e 9. Comparison of monthly survival r a t e s on S.CC. and Telemetry as determined by t r a p p i n g r e s u l t s . N o t i c e the low r a t e s during N o v i - F e b . on both g r i d s and on S.C.C. i n May-June 1 9 7 9 . Sample s i z e s are placed above each column.  38> SURVIVAL N> l III  CO III  1.1.  . . J  I.  RATE I  (O  00  I  o  00  CO 00  CO  O)  CO I  CO  m  z o <  CO  •  I  m 03  (0  I  -J  >  CO  ro -si  N>  O O  -0  TABLE 2  S u r v i v a l r a t e s of j u v e n i l e s from f i r s t t r a p p i n g to Way 1. I n d i v i d u a l s were divid-ed according t o l i t t e r group by weight at f i r s t c a p t u r e . Sample s i z e s are i n brackets*  L i t t e r No.  1  2  3  Total  S.C.C.  0.33 (9)  0.15 (20)  0*0 (8)  0. 16(37)  Telemetry  0.33 (12)  0.17 (29)  0.0 (8)  0. 18(49)  Combined  0.33(21)  0.16 (49)  0.0 (16)  0. 17 (86)  no  than 20%. T h i s was the same as 10 ) .  Juvenile  annual  rates  compares with  survival  ( 2  of  s u r v i v a l d i d not decrease throughout the winter  as suggested by K e i t h and Windberg survival  adult  were  .92  rates  of  ( 1978  ). . Monthly  telemetry  ( n=23 ) from Sept. 1 - Dec._1..This .88  ( n=23 )  from  Dec.  1 - May  15.  Trapping s u r v i v a l r a t e s showed s i m i l a r changes. . Table  3  shows  the proximate causes of death of 38 r a d i o -  c o l l a r e d animals. Predators were r e s p o n s i b l e f o r 24 cases  in  which  the  cause  it  was  sometimes d i f f i c u l t  of  tried  the  individuals  end  were  of  a  found  appears t h a t death was  in  long  continuous  forms  found  died  because  completely  of  poorly  spell.  The  undisturbed. I t triggered  by  ( Pease et al..1979 ) . Four fitting  c o l l a r s which became  lodged between t h e i r upper and lower jaws. They were  4.2.  reduce  were  cold  probably due to s t a r v a t i o n  long p e r i o d of c o l d temperatures  animals  eat  to  with no s i g n s of p r e d a t i o n . A l l of these occurred i n e a r l y  March near  the  predation  problem by p l a c i n g f i n d s where there was some doubt i n the  unknown cause o f death category. Only t h r e e animals dead  27  to determine whether animals had  been predated or scavenged a f t e r they d i e d . I this  the  of death c o u l d be determined. T h i s  f i g u r e i s probably an o v e r e s t i m a t i o n of the e f f e c t as  of  unable  to  and thus s t a r v e d .  Discussion  Since  changes  in  numbers and s u r v i v a l r a t e s are i n t e g r a l  p a r t s of the snowshoe hare c y c l e i t i s important t h a t the v a l u e s obtained a c c u r a t e l y r e f l e c t the events o c c u r r i n g . The f a c t  that  TABLE 3  Causes o f death of radio-tagged  Predator  hares.  Starvation  Collar  Unknown  Caused Terr. 10  avian 9  Unknown 5  3  4  7  42  the  changes  enumeration  i n numbers  determined  technigues were s i m i l a r  by the J o l l y and complete  throughout  the study support  the v a l i d i t y of the e s t i m a t e s as an index of d e n s i t y . H i l b o r n et al.  ( 1976 ) found t h a t M.N.a.  by  10-20%.  underestimated  vole  populations  I f t h i s amount i s added t o the M.N.A., estimates i n  t h i s study, f i n a l values are comparable t o those obtained by the J o l l y technique. T h i s  t o o , suggests  that  the estimates  are  correct. S u r v i v a l e s t i m a t e s determined (up  to  factors. and  35%)  than  those  from  by t r a p p i n g were always lower t e l e m e t r y . T h i s was due to two  F i r s t l y , t r a p p i n g cannot  differentiate  between  death  e m i g r a t i o n . An animal l e a v i n g t h e g r i d e n t i r e l y o r s h i f t i n g  i t s home range appear  to  so that i t s  have  chances  of  capture  are low  d i e d . Secondly, t e l e m e t r y estimates a r e b i a s e d  s l i g h t l y h i g h . T h i s i s because animals l o s i n g t h e i r subsequently  dying  before  radios  and  being r e t r a p p e d are n o t i n c l u d e d i n  the d e t e r m i n a t i o n of telemetry s u r v i v a l r a t e s . Those their  will  that  lose  c o l l a r but are retrapped before they d i e are i n c l u d e d . As  a r e s u l t the chances o f missing an animal t h a t d i e s are g r e a t e r than  missing one t h a t s u r v i v e s . T h i s b i a s was s m a l l however, as  only 8 o f 116 radio-tagged animals disappeared with no as t o t h e i r  fate.  Trapping s u r v i v a l determined  evidence  by  r a t e s were s i g n i f i c a n t l y lower than  telemetry  i n t h e Nov. 1978 t o Feb.  those  1979 p e r i o d .  T h i s was probably due t o the f o l l o w i n g . A number o f radio-tagged animals were found dead i n l a t e Feb. animals  died  at  a  time  - e a r l y March  1979.  These  three months a f t e r the l a s t t r a p p i n g  s e s s i o n i n November 1978 and one week before the f i r s t  session  43  i n March 1979. many  of  all  Because November was  these i n d i v i d u a l s ,  of  the  estimates  losses  on  the  between the two  in  t r a p p i n g s u r v i v a l would c o n c e n t r a t e  the  other  Nov.  hand,  p e r i o d s . The  the l a s t time of capture f o r  would  end  s u r v i v a l r a t e s by the t r a p p i n g  - Feb.  period.  Telemetry  spread them more evenly  r e s u l t i s an underestimation technique  in  the  Nov,  -  of  Feb.  period. Trapping  s u r v i v a l r a t e s were a l s o s i g n i f i c a n t l y lower  telemetry e s t i m a t e s i n May low  trapping  - June 1979.  T h i s was  s u r v i v a l estimates on S.C.C.  the  which was  than  result  of  caused  by  the f o l l o w i n g s i t u a t i o n . F i r s t l y , as r e v e a l e d by t e l e m e t r y , many animals on S.C.C. May  to s l i g h t l y  movement  s h i f t e d t h e i r home ranges from on the g r i d i n  o f f i t f o r the  decreased  trappability  the  the  of  the  summer.  This  chances of capture as shown by the  of animals on S.C.C.  s i t u a t i o n occurred i n 1978 to  duration  i n May  - June 1979.  low  A similar  but high s u r v i v a l and a l a t e r  return  g r i d allowed most of the animals t o be r e c a p t u r e d . With  t r a p p i n g being stopped  i n 1979  recaptured  were recorded as having d i e d . The  r e s u l t was  and  thus  to b i a s  trapping  however,  survival  the  animals  downward  in  were  not  overall  May  - June  1979. The  above s i t u a t i o n s exemplify the value of telemetry as a  method of e s t i m a t i n g s u r v i v a l r a t e s . Because animals do not have to  be  regularly  affecting Telemetry  trapped  trappability  has  to  supply no  information,  influence  on  behavior  survival  s u r v i v a l estimates then, are u n a f f e c t e d by home  s h i f t s or d i s p e r s a l  movements and thus present a c l e a r e r  of s u r v i v a l than do t r a p p i n g methods.  rates. range picture  4.2-1. Reproduction  The  earlier  dates  of  first  litter  c o n c e p t i o n s i n 1979  compared t o 1978 seemed t o be l i n k e d p r i m a r i l y with the onset o f s p r i n g . Snow disappeared and new growth began two weeks in as  1979 than i n 1978. In both years f i r s t l i t t e r s  earlier  were born  just  t h i s new growth became r e a d i l y a v a i l a b l e t o the females. The  l i n k a g e between onset of s p r i n g  and breeding seems t o be  among  K e i t h 1971; Cary and K e i t h 1979;  leporids  ( Meslow  Wight and Conaway  and  1961 ) .  R e s u l t s showed t h a t during 1978 twice female  were  common  as  many  young  caught on the Telemetry as on S.C.C..One p o s s i b l e  e x p l a n a t i o n i s t h a t females on Telemetry a c t u a l l y produced as many young as those on S.C.C. I do not t h i n k case.  The  per  this  twice  was  d i s c r e p a n c y was probably due t o the r e l a t i v e  arrangements of animals on each g r i d . Radio-telemetry  the  spatial  locations  showed t h a t females on Telemetry spent most of t h e i r time on the actual off  grid  while those on S.C.C  i n p e r i p h e r a l areas. As  chance  that  juveniles  on  Consequently, they had to Telemetry  as  move  were  greater  fairly  born  was  a  greater  o f f the g r i d .  distances  c l o s e to  at l e a s t u n t i l weaning ( Rongstad  initially,  there  than  their  c o u n t e r p a r t s before there was any chance of c a p t u r i n g  means there was l e s s chance of on  Telemetry.  always  their  place  of  and T e s t e r 1971 ) . T h i s  capturing  juveniles,  S.C.C. T h i s e x p l a i n s why f i r s t  respective l i t t e r s on  result,  S.C.C.  them. J u v e n i l e s seem t o remain birth  spent c o n s i d e r a b l y more time  at  least  c a p t u r e s f o r the  occurred 10 days l a t e r on S.C.C.  than  45  Another c o m p l i c a t i n g f a c t o r may have been the the  removal  grid  ( F i g . 1 ).  habitat r e l a t i v e l y created  by  close  to  of  T h i s area was a b l o c k of vacant  S.C.C.  and  Telemetry  and  was  l i v e - t r a p p i n g and removal o f hares. T h i s unoccupied  h a b i t a t may have i n f l u e n c e d rather  presence  than  onto  animals  S.C.C.  to  move  into  this  area  Over 40 j u v e n i l e s were caught i n the  removal area. T h i s was more than enought d i f f e r e n c e s observed between S.C.C.  t o compensate  f o r the  and Telemetry.  The above f a c t o r s may have caused the d i f f e r e n c e s i n number of young caught per adult female on each of the two study a r e a s . If  12.25,  the  number  of  young  caught  per  a d u l t female on  Telemetry, i s taken as an estimate o f average n a t a l i t y r a t e s the  a r e a , the value i s r e l a t i v e l y high. Cary and K e i t h  provide r e a l i z e d  of  6.6.  Ernest  ( 1974 )  were  not  computed  Evans  ( 1940a )  provide  found v a l u e s as high as 11.7  young per female d u r i n g a hare peak figures  ( 1979 )  n a t a l i t y r a t e s o f 11.3 t o 16.3 young per female  during i n c r e a s e years while Green and values  in  from  in  Central  Alaska.  These  the number of young e n t e r i n g  t r a p s but from mean values of l i t t e r  s i z e s , pregnancy r a t e s , and  adult s u r v i v a l . The number o f young a c t u a l l y being caught  would  undoubtedly be somewhat l e s s .  4.2-2. Changes i n Numbers  Numbers to s p r i n g increasing  doubled  on S.C.C.  1979. T h i s r a t e hare  of  and Telemetry from s p r i n g  change  seems  characteristic  p o p u l a t i o n s ( Green and Evans  1978 of  1940b; K e i t h and  46  Windberg 1978 throughout temporary  ).  the  M.N.A. fall  and  and  Jolly  remained  high  then d e c l i n e d over w i n t e r . The  sharp  d e c l i n e i n October was  estimates  not  completely  due  to  lower  s u r v i v a l although r a t e s d i d drop from summer t o Sept. - Oct.. to  October  any  l o s s e s were compensated f o r by new  showing up i n t r a p s . The same was though,  no  -new  rain  made  than i t a c t u a l l y  trapping  most of the t r a p s i n o p e r a b l e and  decreased larger  was.  untagged  i n d i v i d u a l s may  session.  of t h i s , the drop i n October appeared  The i n c r e a s e i n numbers i n e a r l y A p r i l was of  October  i n d i v i d u a l s were captured. T h i s c o u l d have been  the catch..Because  numbers  individuals  t r u e f o r November. In  caused by poor weather c o n d i t i o n s d u r i n g the Freezing  Up  individuals  showing  up  a l s o due to high i n t r a p s . These  have been present on the g r i d d u r i n g  winter  or  more l i k e l y , e x i s t e d on the edge of the g r i d , and with the onset of  breeding,  became more mobile  ( Hewson 1976  with a p o s s i b l e expansion of home range, may chances  of  capture  as  suggested  ) . _ T h i s , coupled  have i n c r e a s e d  the  by the high t r a p p a b i l i t y  of  males at t h i s time. The decrease i n numbers i n May only  - June 1979 can,  p a r t l y e x p l a i n e d by m o r t a l i t y l o s s e s . The  trapping a r t i f a c t . trapped  were  still  Although alive  many at  the  of  the end  previously  June, as shown by  t e l e m e t r y s u r v i v a l e s t i m a t e s , they were not captured during final  trapping  session.  The  be  r e s t i s due to a  animals of  again,  the  p o p u l a t i o n e s t i m a t i o n techniques  would then record them as dying and thus reduce  population  size  a c c o r d i n g l y . T h i s r e s u l t s i n numbers being underestimated at the end of the study.  47  4,2-3. S u r v i v a l  An  annual  adult  survival  of  20%  i s r e l a t i v e l y low f o r  i n c r e a s i n g hare p o p u l a t i o n s . K e i t h and Windberg values  ( 1978  )  g r e a t e r than 30% i n A l b e r t a p o p u l a t i o n s . J u v e n i l e s  suffered survival rates  significantly  rates  to  were  comparable  Windberg 1978; losses  those  Dolbeer and C l a r k  throughout  the  study  lower  than  of other s t u d i e s 1975  ).  appeared  Proximate to be due  have  been  related  to  changes  in  s u s c e p t i b i l i t y t o predation..There was  cover  never  adults  and  ( Keith  and  causes  of  to predation.  Losses seemed t o i n c r e a s e s l i g h t l y from summer t o winter, may  found  and  very l i t t l e  which  subsequent  evidence  of  s t a r v a t i o n or d i s e a s e . To  conclude,  numbers  doubled  over the study even  a d u l t s u r v i v a l was lower than t h a t found i n other s t u d i e s . seemed  to  be  compensated  rates. Juveniles survived Survival  rates  were  f o r by higher than average as  slightly  well  as  adults  at  though This  natality  a l l times.  lower i n winter months and most  l o s s e s had p r e d a t i o n as t h e i r proximate  cause.  48  5. HOME RANGE SIZE AND SPATIAL ARRANGEMENT  Home range was d e f i n e d by Burt traversed  by  the  individual  "... t h a t  area  i n i t s normal a c t i v i t i e s of food  gathering,  mating,  activities  are performed i n t u r n , determines the type of s o c i a l  organization knowing  and  ( 1943 ) as  experienced  such  things  caring  by as  f o r young."  that  The  individual*.  the s i z e ,  way  these  Consequently,  location,  and  spatial  arrangement of the home ranges o f a group of i n d i v i d u a l s provide  some  i n f o r m a t i o n as to t h e i r s o c i a l o r g a n i z a t i o n . T h i s  concept i s p a r t i c u l a r l y important hare  where  i n species l i k e  the  With  relatively  easy t o o b t a i n an a c c u r a t e  a  of  the  development  of  radio-telemetry  and  i t is  measure of t h e p o s i t i o n o f  hares' heme ranges. T h i s s e c t i o n presents  the s p a t i a l arrangement of snowshoe hares monitored study  snowshoe  i t i s d i f f i c u l t t o observe b e h a v i o r a l i n t e r a c t i o n s  directly.  number  should  discusses  i t s relevance  to  the  data on  during  animals'  the  social  organization.  5.1. Methods  Home ranges were determined by the ( Mohr  1947 )  which  animal i s found t o technique  to  joins  form  include  a only  t h e outermost convex  polygon.  was  done  to  exclude  polygon  method  l o c a t i o n s where an I  modified  this  9058 o f the t o t a l number of p o i n t s .  L o c a t i o n s which were f u r t h e s t from a l l This  convex  locations  others  were  discarded.  representing brief  long  49  d i s t a n c e f o r a y s o u t s i d e an animal's normal area 1943  of  use  ) . animal  locations  were  determined  by r a d i o - t e l e m e t r y . As  e x p l a i n e d p r e v i o u s l y , a r a d i o - l o c a t i o n has a s s o c i a t e d an  ( Burt  error  polygon  whose  length  accuracy o f the l o c a t i o n . T h i s telemetry  system  provides  length  some  is a  with i t ,  index  o f the  function  of the  e r r o r and t h e t r a n s m i t t e r s ' l o c a t i o n  relative  to the l o c a t i n g towers. Heezen and T e s t e r  ( 1967 )  have  shown  that the s i z e of a home range i s a f f e c t e d by the accuracy of the points  involved.  To  see  how the e r r o r of my telemetry system  a f f e c t e d home range s i z e I performed the f o l l o w i n g  analysis.  P o i n t s were p l a c e d a t v a r i o u s p o s i t i o n on a map. These were used as c e n t r e s of h y p o t h e t i c a l sguare area  home  ranges  having  an  e q u a l t o 3 ha. One of these ranges can be seen i n F i g . 10.  When using the convex polygon method the s i z e of a home range i s a f f e c t e d most by the boundary.  locations  To  obtain  influential an  the  i n overall  home  bearing  locating  and  a  mean  equal  towers  locations  black dots  to  f o r each  i n F i g . 10  corner.  and  in  were  size  I determined t h e ( F i g . 10 ) .  the  actual  combined  from a corner  95% c o n f i d e n c e i n t e r v a l of 3 ( t e l e m e t r y  e r r o r = 3° ) . B e a r i n g s from each tower  locations  actual  range  b e a r i n g s f o r each corner were generated by computer  normal d i s t r i b u t i o n with a  five  form  e s t i m a t e of t h i s e f f e c t  bearings o f each c o r n e r from two Five  which  In t u r n , the e r r o r i n v o l v e d i n e s t i m a t i n g these outer  p o i n t s w i l l be most error.  outer  system  to  give  They are r e p r e s e n t e d by the  effect,  mimic  the range  of  a t e l e m e t r y system with a 3° e r r o r would produce when  l o c a t i n g an animal on the boundary  of  i t s home  range.  When  50  F i g u r e 10. Method used t o determine the e f f e c t of telemetry e r r o r (3°) on estimated home range s i z e .  system  51  52  combined  to  produce a 90% home range these p o i n t s  w i l l give an  e s t i m a t e o f the a c t u a l range. The  error  location  i n estimating  estimate  -  home  actual  the  ( F i g . 10 ) .  area  ( i . e . radio  area ) i s a f u n c t i o n of where the  home range i s s i t u a t e d r e l a t i v e towers  range  to  the b a s e l i n e  of  the two  An index o f t h i s l o c a t i o n i s the l e n g t h o f  e r r o r polygon of the r a d i o l o c a t i o n s which i s r e p r e s e n t e d by  AB i n Fig..10. The e r r o r polygon i s s m a l l e s t  when t h e home range  i s a t 45° from each o f the towers and i n c r e a s e s the range d e v i a t e s To  predict  in  length  when  from t h i s p o s i t i o n . and  therefore  c o r r e c t the e r r o r i n home range  area, I p l o t t e d a home range e r r o r f a c t o r : ( Estimated area - A c t u a l  area )  ( Estimated area ) against  AB, the e r r o r polygon  length  ( F i g . 11 ) .  AB  i s the  independent v a r i a b l e s i n c e i t can be c a l c u l a t e d f o r any p o s i t i o n relative  to  the  towers  from  the  Estimated area was always g r e a t e r polygon  length  increased  so  known  3°  bearing  error.  than a c t u a l area and as  d i d the o v e r e s t i m a t i o n or e r r o r  f a c t o r . To c o r r e c t home range s i z e s o f animals monitored the  study I determined the e r r o r polygon length  the home range l o c a t i o n and used the r e g r e s s i o n 11 t o c a l c u l a t e the appropriate  error  factor.  range s i z e was then m u l t i p l i e d by (1-error corrected Error  error  associated  during with  equation i n F i g . Estimated  factor)  home  to o b t a i n the  size. polygon  lengths  c a l c u l a t i o n of t h e r e g r e s s i o n .  below When  75  m  lengths  were not used i n the below  this  level  53  Figure 11. Relationship between error polygon o v e r e s t i m a t i o n of home range s i z e . E = estimated range s i z e A = a c t u a l range s i z e .  length  and  54  ERROR  POLYGON LENGTH  (m)  55  were  included  i t was found t h a t t h e r e l a t i o n s h i p between e r r o r  polygon l e n g t h and t h e e r r o r f a c t o r was much poorer This  may  be  ( r = . 65 ) . 2  due t o the f o l l o w i n g s i t u a t i o n . Heezen and T e s t e r  ( 1967 ) found t h a t estimated home range areas remained a c t u a l range s i z e u n t i l e r r o r polygon length reached size.  After  this,  estimated  ranges  showed  equal t o  a  certain  increasing  over  e s t i m a t i o n s i n a f a s h i o n s i m i l a r to t h i s study..There appears t o be an i n f l e c t i o n point then,75 m error  polygon  length  in  this  study,  below  which  i s not r e l a t e d t o home range s i z e  error*  Consequently, I used the r e g r e s s i o n equation shown i n Fig..11 to c o r r e c t the s i z e o f animals' home ranges which f e l l with  error  polygon l e n g t h s g r e a t e r than 75 m and l e s s than 150  m. Those i n areas with g r e a t e r e r r o r was  were d i s c a r d e d  because i t  f e l t t h a t the e r r o r i n v o l v e d was too great to estimate even  the of  i n regions  c e n t r e of t h e home range with any accuracy..Home range  sizes  animals i n areas where the e r r o r polygon length was l e s s than  75 m were l e f t  unchanged. A l l animals on Telemetry were i n  this  category as w e l l as over. 50% of those on S.C.C, The  percentage  determined ranges  i n the  overlap  following  f o r a l l animals  between animals' home ranges were manner.  i n an  The  90%  ( x ) found i n s i d e  the  d e f i n e d by a l l other animals' home ranges was taken as the  percentage o v e r l a p f o r animal ( x ) . Values were determined each  home  area were drawn on a map. The  p r o p o r t i o n of r a d i o - l o c a t i o n s f o r animal area  estimated  animal  i n this  manner and averaged* Overlap by a s i n g l e  i n d i v i d u a l was c o n s i d e r e d the same as o v e r l a p by animals.  for  two  or  three  56  5. 2. R e s u l t s  5.2-1. Home Range S i z e  Fig. female  12 shows the 1978  hares  were s l i g h t l y the  two  radio-tagged  home range s i z e s of male and  on the two study a r e a s . Home ranges  s m a l l e r on Telemetry as compared  to  S.C.C..  ranges  25% l a r g e r than females. F i g *  of  radio-tagged  13  shows  monthly  animals i n 1979. G r i d s have been  separated because range s i z e d i f f e r e d on the two areas. cases  except  In  all  J u l y animals on Telemetry had s m a l l e r ranges.  d i f f e r e n c e s were s i g n f i c a n t f o r males i n Nay and June and f o r females i n June .01)  but  g r i d s were combined t o i n c r e a s e sample s i z e . Wale home  ranges averaged home  monthly  The  ( P<.01  ( P<.001 ) . Males had s i g n i f i c a n t l y  (P <  l a r g e r home ranges than females i n a l l cases except on the  Telemetry area i n May. breeding  and  Home  range  size  appeared  similar  non-breeding seasons. Female home ranges  25% s m a l l e r i n 1979 as compared to  1978. . Average  in  averaged  female  home  range s i z e v a r i e d from 3-5 ha while t h a t of males v a r i e d from 8  )  4-  ha. These f i g u r e s are s i m i l a r to those found i n other s t u d i e s  ( B i d e r 1961; Rongstad contracted  Adams 1959, and  their  Tester  O'Farrell ( 1971  1965 ). )  found  that  female  hares  home range s i z e j u s t p r i o r t o p a r t u r i t i o n .  see i f t h i s occurred i n my study I compared home range s i z e the  two week p e r i o d centred around each b i r t h  period midway between b i r t h s i n 1978, this  to  weekly  while i n  To for  with the two week 1979  I  reduced  i n t e r v a l s . In each case the number of l o c a t i o n s  used t o determine home ranges f o r b i r t h and  interbirth  periods  57  F i g u r e 12. Mean monthly home range s i z e s o f radio-tagged hares i n 1978 showing that males have s l i g h t l y larger ranges than females. Narrow bars r e p r e s e n t 95% c o n f i d e n c e limits. Sample s i z e s are placed above each column.  58  12 11  FEMALES  10  MALES  O  9 8 I .7 6  <  x  11  X  10 18  5 17  4 . ~ 3 .. 2 . . 1 ..  JUNE  JULY  AUG  SEPT  NOV  59  F i g u r e 13. 1979 mean monthly home range s i z e s o f radio-tagged hares. Females had s i g n i f i c a n t l y s m a l l e r (t-test, P < .01) home ranges than males i n a l l cases except on Telemetry i n Way and J u l y . Narrow bars r e p r e s e n t 95% c o n f i d e n c e intervals. Sample s i z e s are paced above each column.  o U3  F E M A L E S  01  MALES  •  9. 8. 7. X  61  4. .  13  15  3. . 15  2. . 1. .  MAY  JUNE S.C.C.  JULY  MAY  JUNE TEL.  JULY  61  were e q u a l . T h i s was done t o avoid b i a s e s due t o sample s i z e s as pointed  out  by J e n n r i c h and Turner  ( 1969 ). R e s u l t s are shown  i n F i q . 14. Home ranges were very s m a l l sampling  during  p e r i o d s of 1978* T h i s i s probably  the  first  two  due to the f a c t  that  l o c a t i o n s during t h i s time were determined by using antenna  to  get  very near the animal.  underestimation  of home range s i z e .  p e r i o d s average home range vs. i n t e r b i r t h birth in  periods.  and i n t e r b i r t h  size  was  handheld  As a r e s u l t animals were  l o c a t e d d u r i n g d a y l i g h t hours o n l y , which may have an  a  resulted  A f t e r these two i n i t i a l  35%  lower  during  birth  The o n l y s i g n i f i c a n t d i f e r e n c e between  p e r i o d s was t h a t of l i t t e r  1  on  Telemetry  1979 ( P<.01 ) when b i r t h ranges were 40% s m a l l e r than  of i n t e r b i r t h  in  those  periods.  5.2-2. Percentage  Overlap  Home range o v e r l a p o f males and females during the breeding season  was  analyzed  themselves s p a t i a l l y  to  F i g . 16.  The  p e r i o d s centered  how  individuals  arranged  a t t h i s time. F i g . 15 shows t h a t female 90%  home ranges overlapped in  determine  e x t e n s i v e l y . A c t u a l percentages are shown  breeding around  season  and  was  between  again  broken down i n t o  the b i r t h  of  litters.  Average o v e r l a p was never l e s s than 30% and was 20% lower d u r i n g birth  ( 40% ) v s . i n t e r b i r t h  ( 60% ) p e r i o d s .  Female home range overlap was f u r t h e r analyzed if  intensively  overlapped these  used  areas  of  an  individual's  to determine range  were  by o t h e r s . 50% home ranges were taken as r e p r e s e n t i n g  more i n t e n s i v e l y  used  areas  as  suggested  by  Michener  62  F i g u r e 14. Mean home range s i z e s o f females showing smaller range s i z e s during b i r t h versus i n t e r b i r t h periods. Grids have been combined except d u r i n g the b i r t h of l i t t e r 1 i n 1979 when home ranges i n the two areas were significantly different. Narrow bars represent 95% confidence i n t e r v a l s . Sample s i z e s are placed above each column.  9. 8_  BIRTH  7_  Q  INTERBIRTH  6. . 5. .  < X  4. .  8  SCC.  3.  20  2.  TEL.  21 18  1J:  LITTER 19 78  25  NO. 19 7 9  64  F i g u r e 1 5. . Female 90% home ranges on S.C.C. d u r i n g the breeding season.  showing e x t e n s i v e  overlap  MAY 1 5 - 30 1979  150 m  66  F i g u r e 16. % overlap of female home ranges during birth vs.. interbirth periods. Home ranges were determined over two week i n t e r v a l s i n 1978 and weekly i n t e r v a l s i n 1979. All percentages have been transformed by arc s i n e square r o o t function. 95% confidence i n t e r v a l s are shown by narrow bars and sample s i z e s are placed above each column. N o t i c e the lower amount of o v e r l a p during b i r t h p e r i o d s .  10 0.. BIRTH 9 0- .  Q  INTERBIRTH  8 0. .  7a . 6 0- 5a -  11 8  4 0. 3 0. 2 or 10.  JULY 3  AUG 8  JULY 21  AUG 26 LITTER  19 78  MAY 16 NO.  MAY 26  JUNE 5  1  JUNE 13  JUNE 25 2  1979  68  ( 1979 ) . The 50% home range of an i n d i v i d u a l female was p l o t t e d on  a  map  and  superimposed to  the  90%  ranges  o f a l l other i n d i v i d u a l s were  on i t . Percentage o v e r l a p was determined and  found  be as high i n these 50% areas as i t was when 90% home ranges  were c o n s i d e r e d . There  was no s u g g e s t i o n  that  females  avoided  areas used e x t e n s i v e l y by another female. Male 90% home ranges a l s o overlapped e x t e n s i v e l y during the breeding  season  as  values were never overlapped  shown  less  in  than  F i g . 17.  35%.  As with females, mean  F i g . 18  shows  as  males  females and d i d not exclude other males from females  w i t h i n t h e i r range. An i n d i v i d u a l male could come with  that  many  as  seven  into  contact  females but the average was j u s t over  three. Animals d i d not change t h e i r s p a t i a l of  the  breeding  season.  arrangement  outside  F i g . 19 shows t h a t i n November  ranges c o n t i n u e d t o o v e r l a p between similar  arrangements  and  within  sexes,  1978, and  a  o c c u r r e d i n e a r l y March 1979. I t seems t h a t  hares never exclude i n d i v i d u a l s of the same or o p p o s i t e sex from p a r t o r a l l of t h e i r home range at any time of the year.  5 2-3. X  Dispersal  The m a j o r i t y  of  animals  radio-tagged  during  the  study  occupied t h e same home range throughout the year. However, 14 o f 116  tagged  individuals  did  undergo  dispersal  D i s p e r s a l was c o n s i d e r e d t o be any movement i n which left  i t s home  range  movements. an  animal  and did not r e t u r n . Table 4 l i s t s the 14  d i s p e r s e r s along with t h e i r  age,  sex,  time  and  distance  of  69  F i g u r e 17. 90% heme ranges of males on S.C.C. d u r i n g the breeding season.  showing  high  overlap  M A Y 15 - 30  1979  / N  150 m  71  F i g u r e 18. . 90% home ranges of 3 males ( ) and 5 females (- - -) S.C.C. showing high o v e r l a p between and w i t h i n sexes.  on  M A Y 15-30 1979  ,Hrc  100 m  \  73  F i g u r e 19. 90% home ranges o f males ( ) and females (- - -) study areas during November 1978. Notice the between and w i t h i n sexes.  on the overlap  1U  S.C.C.  75  TABLE 4  S t a t u s g r i d t i m i n g o f movement,distance moved,and f i n a l of hares d i s p e r s i n g during the study. #  #  GRID  STATUS LITTER SEX  sec see sec sec sec sec sec Tel. . Tel. , Tel. . Tel. Tel. Tel. Tel.  *  1 1 2 2 2 1 2 2 1 2  AGE AT DISPERSAL  m m  juv. juv.  f f f f f f f m m f  ad. juv. juv. juv. ad. juv. ad. juv. juv. juv.  f f f  ylng ad. ad.  TIME OF DISPERSAL  J u l y 28/78 July 29/78 Sept. 3/78 Nov. 12/78 Dec-Fab Dec-Feb Dec-Feb May 2 0 / 7 9 J u l y 29/78 July 30/78 Sept.,25/78 Sept. 26/78 Oct. 3 0 / 7 8 ** A p r i l /79 Nov-Mar May 5/79 June 2 0 / 7 9  DIST. . MOVED (M)  850 860 1524 2670 460 500 460 2290 760 1200 890 840 615 615 1000 915 1370  •caught i n p e r i p h e r a l t r a p s near Telemetry G r i d ••animal returned to i t s o r i g i n a l home range  fate  FATE  mortality dispersed mortality mortality mortality mortality removed unknown unknown mortality mortality unknown dispersed removed alive alive removed  76  movement,  and  their  female which l e f t area  700  meters  final  fate.  Included  i n the t a b l e i s a  i t s home range i n l a t e October  to  occupy  an  away. I t remained i n t h i s l o c a t i o n u n t i l mid-  March 1979 a t which time i t returned t o i t s o l d home range. T h i s was  the  only  animal  which  showed  this  migratory  type  of  movement. Dispersal  was  p r i m a r i l y by j u v e n i l e s but d i d occur i n a l l  age and sex c l a s s e s with the e x c e p t i o n of a d u l t males. T h i s  was  probably due t o the f a c t t h a t few a d u l t males were r a d i o - t a g g e d . Animals  d i s p e r s e d a t a l l times throughout the study and moved a  mean d i s t a n c e of 1045 meters. Of the 10 animals which prior  to  May  dispersed  1979 and whose f a t e was known, t h r e e s u r v i v e d t o  breed i n 1979. Only two animals d i s p e r s e d a f t e r May 1, 1979 and both s u r v i v e d t o breed i n t h e i r new range.  5.3.  Discussion  A  wide  v a r i e t y of t e c h n i q u e s have been used t o d e f i n e the  home ranqe of an animal 1969 ) .  Each  1954;  polygon method because of i t s  prominence.  estimates  in  against t h e number of increased  with  and  Turner  simplicity  and  I t s major shortcoming i s t h a t as sample  s i z e i n c r e a s e s so does home range s i z e . To affected  Jennrich  has i t s f a v o r a b l e and unfavorable p o i n t s . I chose  to use the convex historical  ( Stickel  this  study  radio-locations  additional  locations  I  see  how  this  p l o t t e d home range used.  Home  range  bias size size  u n t i l a t o t a l o f 20 were  reached, at which time an i n c r e a s e i n l o c a t i o n s caused l i t t l e o r no i n c r e a s e i n range s i z e . As a r e s u l t I t r i e d t o use  at  least  77  20  points  f o r a l l home range e s t i m a t e s . As a f u t h e r p r e c a u t i o n  a g a i n s t sample  s i z e b i a s , a l l comparisons  of  home  range  size  were made with v a l u e s estimated from equal numbers of l o c a t i o n s . The  relative  population w i l l of  s i z e and s p a t i a l arrangement  depend  of members o f a  t o some e x t e n t on the s o c i a l  that group. Knowing the s o c i a l o r g a n i z a t i o n of  then,  should  allow  one  to  predict  organization a  the type  of  members.  this  whose s o c i a l o r g a n i z a t i o n i s  for a  species  unknown should allow one t o make  inferences  turn,  spatial  o r g a n i z a t i o n o f home ranges of i t s arrangement  In  population  about  knowing  i t s social  system* I w i l l now t r y to do t h i s f o r snowshoe hares. If  t h e breeding season i s considered f i r s t ,  b a s i c types of s o c i a l 1977;  Jewell  1976 ) .  i n v o l v e d and monogamous  organization  can  be  systems  These  shown  by  a r e based  defined  as  mammals  ( Crook  on t h e mating  monogamy  and  systems  polygyny.  In  males mate with a s i n g l e female and u s u a l l y  p a r t i c i p a t e i n the r e a r i n g of young.  One would expect home range  s i z e s t o be s i m i l a r between sexes and the overlap  there a r e two  extensively.  Neither  ranges  of  pairs  to  of these occurred i n t h i s study.  Male home ranges were l a r g e r than females' which agrees with the f i n d i n g s o f Bider one  male  with  hares mated  ( 1961 ) . A l s o , there was one  with  female.. Severaid  more  than  one  no  association  of  ( 1942 ) found t h a t male  female.  It  seems  unlikely  t h e r e f o r e , that hares have a monogamous mating system. Polygynous  mating  systems  a r e those i n which males mate  with more than one female. The way i n which they to  additional  spatially  females  determines  how  their  arranged. The v a r i o u s methods can be  obtain  access  home ranges a r e grouped  i n the  78  f o l l o w i n g manner: ( 1 )  home  range  abandonment - Smith  ( 1968 ) found t h a t  male red s q u i r r e l s abandon t h e i r r e g u l a r home ranges d u r i n g the  b r e e d i n g season t o roam over r e l a t i v e l y  search  of  receptive  females.  would be extremely l a r g e d u r i n g probably  bear  no  relationship  l a r g e areas  in  In t h i s system  male ranges  the  season  breeding  to their i n i t i a l  and  position  p r i o r to breeding. ( 2 )  territorial  characterized to  polygyny  males or i n d i r e c t l y  by females would  This  mating  system  by breeding males o b t a i n i n g e x c l u s i v e  females e i t h e r d i r e c t l y  other  -  by  defending  females  larger  home  ranges  than  of  home  their  territorial territories  ).  and would  importantly,  home  p r e v e n t i n g other male access ranges.  A  variation  of  to  this  females type  system i s one i n which males defend very through which  T h i s i s found i n a 1974  males  range o v e r l a p would be minimal as a r e s u l t  males a c t i v e l y  in  against  case  females  o v e r l a p more than one female home range. More male-male  rights  by defending a resource r e q u i r e d  ( Emlen and Oring 1977 ) . I n e i t h e r  show  Home  is  number  ranges  of  of  small  females move i n search of mates. of  ungulate  species  ( Jarman  males i n t h i s s i t u a t i o n would be  s m a l l e r than those o f females. ( 3 ) dominance h e i r a r c h y polygyny - In t h i s gain  access  to  system  males  females by being b e h a v i o r a l l y dominant t o  other males i n the a r e a . A dominant male  would  then  have  access t o any females w i t h i n i t s home range. Home ranges of males  would  again  be  larger  than those of females. The  79  major d i f f e r e n c e from a t e r r i t o r i a l  polygynous system  would  be t h a t male home ranges would o v e r l a p both female and male ranges. Males would not e x h i b i t e x c l u s i v e a r e a s . . (  ) promiscuous polygyny - T h i s system would possess  same  spatial  system. In female's  organization  this  home  case  of home ranges as the p r e v i o u s  however,  range  the  any  male  overlapping  a  would have an egual chance o f mating  with t h a t female. There would  be  no  differential  access  according t o aggressive i n t e r a c t i o n s between males. The  spatial  arrangement  of  most s i m i l a r t o that p r e d i c t e d by promiscuous  snowshoe hare home ranges i s t h e dominance  hierarchy  polygyny system. Males show l a r g e r home ranges than  females and there i s high male-male o v e r l a p . The f a c t t h a t did  or  males  not maintain e x c l u s i v e areas r u l e s out the p o s s i b i l i t y of  territorial  polygynous  system e x i s t i n g . As w e l l , the f a c t  males remain i n t h e i r pre-breeding home breeding  season  makes  the  u n l i k e l y . I t i s impossible t o hierarchy range  home  ranges  range  throughout  abandonment  differentiate  between  a  that the  system  dominance  and promiscuous polygyny systems on the basis o f home  spatial  arrangements  alone.. Doing  so  would  require  b e h a v i o r a l or g e n e t i c d a t a . Observations i n the w i l d or i n l a r g e enclosures  would suggest whether c e r t a i n males were dominant t o  o t h e r s . G e n e t i c markers c o u l d be females  a  used  to  determine  how  many  male mates with. I n a promiscuous system t h i s should  be r e l a t i v e l y even among males while i n a  dominance  hierarchy  some males should do t h e majority of mating. The  various  spatial  systems  discussed  so f a r have been  r e l a t e d to how the male attempts to o b t a i n mates. Unlike  males,  80  female home range l o c a t i o n the  offspring  themselves rearing  should be dependent on the welfare o f  as well as mate s e l e c t i o n .  then, i n a manner t h a t  young  to  be  met.  Females should arrange  allows  One  of  the  requirements  these might  or  be a s u i t a b l e  p a r t u r i t i o n s i t e . B i d e r ( 1961 ) f e l t t h a t female snowshoe hares were t e r r i t o r i a l Tester  ( 1971 )  just prior  to  parturition  territorial  t h e i r home ranges should show l i t t l e case.  Percentage  p a r t u r i t i o n but s t i l l was  most  likely  by  and  overlap remained  during  this  d i d decrease d u r i n g p e r i o d s o f g r e a t e r than  35%.  The  due to t h e f a c t t h a t home range s i z e  chance  alone.  period  or no o v e r l a p . T h i s was not  and consequently, the amount o f o v e r l a p decrease  Eongstad  found t h a t females c o n t r a c t e d t h e i r home range  at t h i s time. I f females were  the  and  would  be  decrease decreased  expected  to  The decrease i n home range s i z e by  females may have been due t o decreased a c t i v i t y at t h i s time and not an attempt  to a v o i d  other  individuals.  However,  ( 1979 ) found t h a t female Richardson's ground defend  territories  core  area.  interactions exclusive  was  areas  s g u i r r e l s d i d not  but c o n t r a c t e d t h e r e range during  and were much more l i k e l y t o be dominant their  Michener  The  dependent were  not  to  degree  and  on  location  maintained*  other  animals  outcome. of then,  pregnancy  aggressive  even  Hares might  in  though  behave i n a  s i m i l a r manner. There i s a p o s s i b i l i t y t h a t females may maintain areas  during  parturition  but do so f o r only a s h o r t p e r i o d of  time. The weekly and biweekly p e r i o d s of a n a l y s i s study  may  exclusive  used  in  this  have been too long to d e t e c t t h i s type.of short term  s p a c i n g . Determining  whether or not t h i s was t r u e would  require  81  i n t e n s e r a d i o monitoring birth.  Enough  locations  accurate estimates The  could  then  be  obtained  the breeding  sex  attempted  season.  to  defend  remained  hares  manner.  resources  gain p r e f e r e n t i a l access  One  heirarchy  possibility  as  observed  Another e x p l a n a t i o n supply study.  i s the by  unchanged  There was no i n d i c a t i o n by  e x c l u s i v e home ranges. T h i s l a c k of t e r r i t o r i a l that  t o produce  o f heme range over s h o r t e r time p e r i o d s .  s p a t i a l arrangement o f home ranges  throughout either  during the time each female was to g i v e  maintaining  spacing  t o resources  formation  suggests  i n some other  of  a  dominance  L i n d l o f ( 1978 ) i n European  could be t h a t resources  are  that  not i n  hares. short  d u r i n g p e r i o d s of i n c r e a s i n g hare numbers such as i n t h i s As a r e s u l t ,  aggressive  spacing  would not n e c e s s a r i l y be  apparent. Hares may i n f a c t , s h i f t t h e i r s p a t i a l arrangement densities  increase  but only f u r t h e r monitoring  as  during peak and  d e c l i n e years would i n d i c a t e whether t h i s i s so. . Dispersal  was  throughout the study. in  primarily  by  juveniles  and  occurred  There d i d not appear t o be a s p e c i f i c time  which the m a j o r i t y of animals d i s p e r s e d . T h i s was s i m i l a r to  the f i n d i n g s o f Windberg and K e i t h factors time.  ( 1976 )  and  suggests  that  t r i g g e r i n g d i s p e r s a l do not a c t or change a t a s p e c i f i c Possible  factors  causing  juvenile  dispersal  will  be  discussed i n a l a t e r s e c t i o n . Lidicker  ( 1975 )  pointed out t h a t two types  can occur i n n a t u r a l p o p u l a t i o n s . The f i r s t , d i s p e r s a l , occurs emigrants  of  termed  of d i s p e r s a l saturation  when p o p u l a t i o n s a r e a t c a r r y i n g c a p a c i t y , and  t h i s type  p h y s i c a l c o n d i t i o n with  are u s u a l l y subordinate little  animals i n poor  chance o f s u r v i v i n g *  The  second  82  type,  pre-saturation  dispersal,  occurs  below c a r r y i n g c a p a c i t y , u s u a l l y during individuals  such  reproductive  potential.  describing  dispersal  population this  as  pregnant The  is  However,  dispersal  d i s p e r s a l was between  own  occurring. I t  these  dispersers  movements  two  types  To during  with  summarize,  method  no  data  or  did  suggesting seems of  male  on  by  t h a t some p r e - s a t u r a t i o n  that  the  dispersal  key  is  and  of  to  ( 1961  e x c l u s i v e areas during resources  deciding  knowing  t h e i r home area  dominance h i e r a r c h y  Bider  the  a number of pregnant females  evidence to suggest t h a t females suggested  of  concerning  whether  or l e f t  dispersers  on  their  and  non-  guestion. female  home range  the breeding season suggests t h a t snowshoe hares  promiscuous  high  and  to answer t h i s high  have  this  populations  Data on the s o c i a l s t a t u s  d i s p e r s e r s would help  which  include  S.C.C.,  were f o r c e d to leave  accord.  and  are  i n d e c i d i n g whether or not  hare  Telemetry were i n c r e a s i n g , and show  females  i s at c a r r y i n g c a p a c i t y . I have  question.  populations  increase,  problem  types  when  overlap have  mating system. There was  defend  parturition  sites  a no as  ). Hares did not attempt to maintain  the non-breeding season, suggesting  were d i v i d e d among i n d i v i d u a l s by some other  that  means.  83  6s_ FEMALE SPACING BEHAVIOR  Keith  ( 1974  )  s t a t e d t h a t lagomorphs, i n c l u d i n g  hares, are "...  incapable  of  determined  available  food  by  K e i t h and  his associates  relationship  between  ( Pease et a l . 1979;  has  self-regulation supplies." been  changes  in  aimed  in  at  Chitty  ( 1960  either  adapted, or prevent  from  l i m i t a t i o n was passed  from  ( Chitty  1971;  enemies so."  about  generation  be  numbers  linked  behavior  on  population  or  climatic  hare  been these  densities  accidents  by  aggressive  to  spacing  behavior  to the next by g e n e t i c mechanisms  in  complicated  ) . I t seems important  behavior,  are  He l a t e r pointed out t h a t t h i s  ways  ( M i l l e r and Watson 1978;  Gibb et a l . 1978  snowshoe  work has  ). F u r t h e r work by o t h e r s has shown t h a t both  and behavior can population  on  doing  brought one  1967  supply  d e s t r o y i n g the food resources t o which they  depending  them  ).,No  food  the  ) p o s t u l a t e d t h a t "... a l l  s p e c i e s are capable of l i m i t i n g t h e i r own without  elucidating  hare numbers and  K e i t h and Windberg 1978  numbers.  densities  Much of the work by  d i r e c t e d toward examining the importance of changes  below  snowshoe  particularly  food  that  limit  Watson and  Miller  then,  to  examine  aggressive  spacing  behavior, and i t s r e l a t i o n to p o p u l a t i o n dynamics.. When the behavior  of animals  cannot be observed  i n d i r e c t methods must be employed to o b t a i n of  this  hand,  understanding  f a c t o r . A number of s t u d i e s have shown t h a t removal o f  v a r i o u s types of i n d i v i d u a l s i s one has  some  first  proven  et a l . 1976  such  indirect  method  that  p a r t i c u l a r l y u s e f u l ( J e n k i n s et al..1963; R e d f i e l d ) . I used t h i s approach to answer the q u e s t i o n :  How  84  are  the  movements of i n d i v i d u a l female hares i n f l u e n c e d by the  presence o f o t h e r females? In other words does use of an area by one hare a f f e c t use of t h a t area by because  there  sensitive  to  another?  I  chose  i s some suggestion t h a t t h i s sex i s p a r t i c u l a r l y other  individuals  just  prior  to  ( Grange 1932 ) . T h i s may be s i m i l a r to t e r r i t o r i a l i n female v o l e s as suggested by Krebs increase,  females  spacing  at  this  time  parturition nest defence  ( 1978a ).,As hare numbers  may  become, more  and  more  important. To examine the i n f l u e n c e of hares on each o t h e r ' s movements I  removed a  group  of  monitored subseguent  females  the  Telemetry  area  and  movements o f the remaining i n d i v i d u a l s . The  b a s i c design of the experiment ( 1 )  from  was t o :  r a d i o - t a g a number o f adjacent females and determine  t h e i r home ranges* ( 2 ) create  a  vacant  area  surrounded  by  radio-tagged  i n d i v i d u a l s by removing the innermost members of the group. ( 3 ) monitor subsequent by  telemetry  and  movements o f the remaining females  compare these movements t o females on a  c o n t r o l area. One would movement  shown  predict by  no  control  difference  between  Conversely,  differences  occupied by other females one would p r e d i c t surrounding  of  the  on  each  other's  would suggest some e f f e c t .  More s p e c i f i c a l l y , i f females were prevented  1. females  types  and experimental females a f t e r the  removal i f females had l i t t l e o r no i n f l u e n c e movements.  the  removal  from  using  areas  that: area  would i n c r e a s e  t h e i r use of t h a t area by s h i f t i n g the boundaries o f  their  85  home range. 2. females  may immigrate from somewhere beyond the r i n g o f  r a d i o - t a g g e d females and come t o occupy the  removal  area.  I f females i n f l u e n c e the movements of other females within home  ranges  and  i n t e r a c t i o n one removal  area  do  would should  so  in  a  predict  manner  that  that  females  causes  their  minimal  surrounding  the  i n c r e a s e use of the p o r t i o n of t h e i r home  range nearest the removal.  6.1. Methods  In March 1979 a l l females on radio-tagged.  To  increase  S.C.C.  and  Telemetry  were  sample s i z e on Telemetry I began t o  trap the area surrounding the g r i d on a weekly b a s i s . Traps were initially  placed on a l l s i d e s of the g r i d a t d i s t a n c e s up to 350  meters away. However, a f t e r a number of that  no  animals  days  i t  became  clear  were present on the western edge of the g r i d .  Consequently, t r a p s i n t h i s area were moved t o p l a c e s of g r e a t e r hare a c t i v i t y .  Any females caught i n p e r i p h e r a l t r a p s or on  actual  were r a d i o - t a g g e d and monitored. Each was l o c a t e d  grids  up t o four times d a i l y ; p r i o r t o 1000 h, 1100-1700 h, h,  and  after  the  1800-2100  2200 h. In most cases animals were a c t i v e d u r i n g  three of these f o u r p e r i o d s . Every week t r a p s were s e t on S.C.C. and Telemetry f c r two days. During t h i s time radio  located  only  once  individuals  each afternoon* T h i s system  roughly 20 l o c a t i o n s per animal between  trapping  were  produced  sessions  and  was followed throughout the experiment. Four  females  were removed from Telemetry on May 12, 1979.  86  Movements o f the remaining 5. C.C.  which  removal,  the home ranges  11 females locating  served  on S.C.C. and  as  animals were compared t o  females  on  as an experimental c o n t r o l . P r i o r t o the of 19 females on the Telemetry  were known from up t o  many  as  18  days  area and of  radio  35 a c t u a l l o c a t i o n s per animal. The  r e l a t i v e l o c a t i o n s of the f o u r i n d i v i d u a l s that were removed can be seen  i n F i g . 20. These s p e c i f i c animals were chosen  following  reasons.  Firstly,  they  were  l o c a t e d on the a c t u a l  g r i d , t h e area i n which 1 was most c o n f i d e n t had  f o r the  that  a l l females  been captured and radio-tagged. As w e l l , t r a p p i n g i n t e n s i t y  was g r e a t e s t i n t h i s area and thus a f f o r d e d the best chances catching  any  new  animals immigrating.  supported  f o u r a d u l t breeding females i n 1978. I t seemed  then, t h a t i t was capable The  animals  Secondly,  t h i s area had likely  of doing so i n 1979.  were removed 10 days before the f i r s t  were born. Remaining i n d i v i d u a l s were monitored at  of  which time the experiment  was repeated*  until  litters  June  20,  R e s u l t s of the f i r s t  removal w i l l be given before d e t a i l s of the second  are o u t l i n e d .  6. 2. R e s u l t s  6.2-1. Removal Number One  6.2-1-1. Use of the Removal Area  To t e s t i f females i n c r e a s e d t h e i r use of the removal I  compared  the  proportion  of  radio  vacated area before t h e removal with t h a t  locations  area  found i n the  afterwards.  Table  5  87  F i g u r e 20. R e l a t i v e l o c a t i o n s of female home ranges on Telemetry before the removal. The dark polygon r e p r e s e n t s the area occupied by the f o u r females (R1, R2, R3, R4) which were removed.  CO oO  PRE - REMOVAL  TABLE 5 Changes i n the p r o p o r t i o n of l o c a t i o n s found i n the removal area f o l l o w i n g the f i r s t removal. HARE NO. T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T1 1 T12 T13 *T14 *T15 *T16 no. animals showing increase  MAY  12-21  +0.45 + 0.10 -0.0 2 -0. 10 + 0.15 + 0.37 + 0.09 + 0.08 -0.06 i 0.0 0.0 0.0 0.66 0.0 6/11  MAY 22-31 -0.30 + 0.03 -0.07 PREDATOR -0.04 +0.06 +0. 13 +0.09 0.0 -0.06 l 0.0 0.0 0.06 0.60 0.11 4/11  KILL  JONE 1-8  JUNE 9-20  -0.01 -0.23 -0.07  +0.05 -0.14 -0.07  -0. 10 0.0 + 0.23 -0. 15 -0.06 -0.06 +0. 29 0.0 0.0 0.09 0.39 0.05  -0. 10 -0.02 + 0.27 -0.01 -0.06 -0.06 + 0.50 0.0 0.0 0.04 0. 86 0. 13  2/12  3/12  • P r o p o r t i o n s f o r these animals r e p r e s e n t the a c t u a l p r o p o r t i o n of l o c a t i o n s found i n the removal a r e a . No l o c a t i o n s were obtained before the removal. - Lost Radio Contact 1  90  shows the changes o c c u r r i n g i n f o u r s u c c e s s i v e p e r i o d s f o l l o w i n g the  removal. I f a l l females a r e c o n s i d e r e d together, use o f the  vacated  area was never s i g n i f i c a n t l y  ( Wilcoxon's individuals increases  signed-ranks ( Hares  test,  T7,T11,  and  greater a f t e r P>.05 ) .  T15 )  the  removal  However,  d i d show  i n t h e i r use of the area. A f o u r t h ,  three  substantial  hare T1, d i d so  f o r one week. Hare  T15 spent the m a j o r i t y o f i t s time a f t e r the  removal  i n the vacated area. U n f o r t u n a t e l y , i t s home range was not known before  the  manipulation. However, i t was never captured i n the  removal area females  prior  that  had  to  the  removal.. A l l  other  radio-tagged  g r e a t e r than 25% of t h e i r r a d i o - l o c a t i o n s i n  the vacated area were  captured  removal. T h i s would i n d i c a t e t h a t  at  least  once  prior  to t h e  hare T15 spent l i t t l e  time i n  t h i s zone before the removal. Hare  T11  was  found  to  have  increased  i t s use o f the  vacated area a f t e r the removal* I t may have done so its  home  range  could  not be determined  sooner  immediately  but  a f t e r the  removal because of a m a l f u n c t i o n i n g r a d i o . F i g . 21 shows occurred  after  that  no  noticable  shift  i n home  t h e removal. Any i n c r e a s e i n use was r e s t r i c t e d  to the outer edges o f the vacated area while the unused. . No area  bulk  remained  animal s h i f t e d i t s home range t o occupy the removal  exclusively. To summarize, although  a few animals  i n use of the area vacated by t h e removal, was  ranges  not  remained  significant unoccupied.  and  the  majority  showed major i n c r e a s e s the of  overall  the  change  removal area  91  F i g u r e 21. Relative locations of female home ranges b e f o r e and a f t e r the f i r s t removal. Dotted l i n e s indicate home ranges o f animals newly tagged after the removal. N o t i c e that t h e removal area remained unoccupied.  PRE-REMOVAL  T9 T8  T5  T6  T3  -K75m  POST-REMOVAL  -EL >T5 T12  ,4-75m  93  6.2-1-2. Home Range age  Females d i d not s h i f t t h e i r home ranges a f t e r but  they  the  removal  may have responded by a l t e r i n g movements w i t h i n  their  home range. I f females avoid each other one would expect them t o use t h e i r home ranges i n a manner t h a t minimized i n t e r a c t i o n . I f so and some i n d i v i d u a l s were removed, females would to i n c r e a s e t h e i r  be  expected  use of the p o r t i o n of t h e i r home range n e a r e s t  the removal area. To  test  analysis.  i f this  The  90%  occurred  pre-removal  I  performed  home  ranges  the of  following  a l l females  surrounding the removal area were determined. I then l o c a t e d the centre  of  the removal area and drew a l i n e from i t through the  a r i t h m e t i c c e n t r e of each female's home range. P e r p e n d i c u l a r each  of  these  l i n e s another l i n e  to  was drawn through the median  p o i n t of each home range. T h i s b i s e c t o r  served  to  divide  the  r a d i o l o c a t i o n s of each female's home range i n t o h a l v e s , l e a v i n g 50%  of  the  locations  on the s i d e of the b i s e c t o r nearest the  removal area. F i n a l l y , these b i s e c t o r s were superimposed on each a p p r o p r i a t e female's home range d u r i n g f o u r c o n s e c u t i v e nine day time p e r i o d s f o l l o w i n g the removal., The locations  on  the  proportion  of  radio-  removal s i d e of the l i n e s were determined i n  each case. Table 6 shows locations  found  t h e changes on  the  Females spent s i g n i f i c a n t l y  in  removal  the  side  more time on  proportion  of  radio  of the b i s e c t i n g  line.  the  removal  side  of  t h e i r home range i n a l l time p e r i o d s except May 22-31 ( Wilcoxon matched  pairs  test  P<.005 ) ,  and the response i n c r e a s e d with  TABLE 6 Home range use by Telemetry females f o l l o w i n g the f i r s t removal. Values r e p r e s e n t the p r o p o r t i o n of l o c a t i o n s f o r each animal i n the h a l f of i t s home range n e a r e s t the removal area* Pre-removal v a l u e s were equal t o 0.50. HARE NO.  MAY 12-21*  T1 T2 T3 T5 T6 T7 T8 T9 T10 T1 1 T12 T13  0.92 0.63 1.00 0.60 0.89 0.76 0.83 0.50 0.14  0.05 0.55 0.87 0.84 1.00 0.25 0.81 0.67 0.?4  0.50 0.81 8/11  no. animals showing increase  l  NS - not * P < ** P < l -• l o s t  MAY 22-31(NS)  JUNE 1-8**  JUNE 9-20** 0.42 0.81 1.00 0.78 1.00 0,88 0.95 0.89  0.67 0.42  0.43 0.64 1.00 0.88 1.00 0.78 0.69 0.82 0.78 1.00 0.69 1.00  8/11  11/12  10/11  l  significant . 025 . 005 radio contact  I  1.00 0.60 0.83  95  time. One  week a f t e r  the  removal,  animals  were  spending  an  average of 2055 more time on the removal s i d e of t h e i r home range and  8 of 11 animals showed p o s i t i v e  increases..By June 1-8  this  had i n c r e a s e d to 30% and 11 of 12 animals. To t e s t i f s i m i l a r occurred  for  S.C.C.  these i n d i v i d u a l s .  d i r e c t i o n a l changes i n  the  range.  The same r e l a t i v e g r i d l o c a t i o n  Table  range  of  was used as a each  the  female's  7 shows the changes i n home range use  removal on Telemetry. Use was never s i g n i f i c a n t l y  from  use  females I performed the.same a n a l y s i s on  midpoint and l i n e s were drawn t o the c e n t r e s home  home  pre-removal  period  after  different  ( Wilcoxon's matched p a i r s  test,  P>.05 ) . I t should be noted however, that animals on S.C.C.  did  show l a r g e s h i f t s i n use of t h e i r home range, but never  any  consistent To  direction.  summarize,  females d i d not respond to the manipulation  by i n c r e a s i n g t h e i r use of the vacated a r e a . However, spend  a  in  significantly  greater  amount  did  of time on the h a l f of  t h e i r range nearest the removal a r e a . S.C.C. show s i m i l a r  they  females  did  not  changes.  6.2-1-3. Number of Immigrants  Another  possible  response by females t o the removal  be long range immigration. In other words, those the  immediately  females  might  other  than  surrounding the removal area might s e t t l e i n  vacated space. I t e s t e d t h i s by measuring the number of  adult  females  being  caught on S.C.C.  and Telemetry a f t e r  removal. The number of immigrants were s i m i l a r  on  both  new the  grids:  96  TABLE 7 Home range use by S.C.C. females a f t e r the f i r s t removal.. Values r e p r e s e n t the p r o p o r t i o n o f l o c a t i o n s f o r each animal i n the h a l f of i t s home range n e a r e s t the removal area. Pre-removal v a l u e s were equal t o 0.50. HARE NO.  MAY  S1 S2 S3 S4 S5 S6 S7 no. animals showinq increase  12-21 (NS) MAY 22-31 (NS) JONE 1-8(NS) JUNE 9~20(NS) l 0.93 0. 08 1.00 0. 53 0. 25 0. 21  0. 11 1 .00 0.00 1.00 0.89 0.50 0.17  3/6  3/7  0.00 0.94 0.00 0.95 0.00 0.00 0. 23  i 0;84 0.00 0.55 0.00 0.07 0.00  2/7  2/6  NS - not s i g n i f i c a n t P > .05 - l o s t radio contact 1  97  four two  females  and four males on Telemetry and t h r e e females  males on S.C.C. T h i s suggests t h a t the removal  influence  on  t h a t the new centre  of  the  Telemetry  did  not  occupy  removal area but e x i s t e d along i t s edges.  p o s s i b l e t h a t these residents  had  no  number of animals immigrating. F i g . 21 shows  animals caught on the  area  and  animals  occupying  the  were  edge  not  immigrants  but  the It i s  rather  of the g r i d . Because they spent  l i t t l e time on the g r i d , they avoided being trapped p r e v i o u s l y .  6.2-2. R e s u l t s of the Second Removal  On June 20, Telemetry  1979,  area.  As  s i x more females were shown  in  F i g . 22,  removed  the  from  the  removal of these  animals served to enlarge the area vacated by removal  one.  remaining  a fashion  animals  were  s i m i l a r to the f i r s t slightly  fewer  bi-weekly  followed  experiment.  until  Aug..1  in  The  The only d i f f e r e n c e s were  that  l o c a t i o n s were taken each week and t r a p s were s e t  rather  than  weekly.  Pre-removal home ranges o f the  remaining i n d i v i d u a l s were determined  from r a d i o l o c a t i o n s taken  during the 20 days p r i o r t o the second  removal.  Table 8 shows the changes i n the p r o p o r t i o n of  time  spent  on the removal area f o l l o w i n g the manipulation. Changes were not significantly removal the  different  ( Wilcoxon's  in  any  of  the periods f o l l o w i n g  matched p a i r s t e s t P>.05 ). Hare  T20  the was  only animal t h a t showed a n o t i c e a b l e i n c r e a s e i n the use of  the area. As w e l l , no new removal  adult females  were  captured  in  the  zone f o l l o w i n g the m a n i p u l a t i o n . . F i g . 23 shows that the  vacated area remained  unused, a r e s u l t i n agreement with t h a t of  98  F i g u r e 22. R e l a t i v e l o c a t i o n s o f f e m a l e home r a n g e s on T e l e m e t r y p r i o r t o t h e s e c o n d r e m o v a l . The r e m o v a l a r e a c r e a t e d by removal of animals (T1, T6, T7, T10, T 1 1 , T15) i s o u t l i n e d w i t h heavy l i n e s .  TABLE 8  Changes i n the p r o p o r t i o n of l o c a t i o n s found i n the removal area a f t e r the second removal.  HAEE NO. T2 T3 T5 T8 T9 T13 T12 T16 T14 T1 8 T20 *T21 *T19 no. animals showing +ve increase  JUNE 20-31  JULY 1-15  JULY 16-31  + 0. 11 -0.06 + 0. 04 + 0.43 + 0.04 -0. 03 + 0.05 -0.09 -0.06 +0.02 + 0.04 0.24 0.0  + 0.04 + 0.03 + 0.33 -0. 03 + 0.08 + 0. 14 + 0.09  • 0.05  7/11  1  0. 0 " 0.0 + 0,19 0. 17 0. 11 7/10  -0.06 I  + 0.06 +0. 13 -0.03 + 0.05 i -0.0 1 + 0.03 + 0.39 0. 17 0.04 6/9  • F i g u r e s f o r these animals represent the a c t u a l p r o p o r t i o n of l o c a t i o n s found i n the removal area. No l o c a t i o n s were obtained before the removal. * - l o s t radio contact  101  Figure 23. R e l a t i v e l o c a t i o n s of female home ranges before and after the second removal. Notice that the majority o f the removal area remained unoccupied.  POST-REMOVAL  103  the  first  removal.  Table 9 shows changes i n home range use removal.  As  with  the  first  removal,  after  the  individuals  i n c r e a s e i n use of the p o r t i o n o f t h e i r home range removal  area  July  and  was  less  nearest the  pronounced  was s i g n i f i c a n t only d u r i n g the l a s t  ( Wilcoxon's matched p a i r s t e s t , P<.05 ) .  that  showed an  and, i n a d d i t i o n , the change i n c r e a s e d with time.  However, t h e o v e r a l l d i f f e r e n c e instance  S.C.C.  females  showed  no  in  Table  similar shifts  shifted  10  pronounced  6.3.  f o l l o w i n g t h e second  shows  i n home range Females  use of t h e i r home range i n a s i m l a r f a s h i o n  each o f the the two removals, although  this  two weeks o f  during the p e r i o d a f t e r the second removal on Telemtry* then,  second  the response  after  was  less  removal.  Discussicn  In  this  experiment  I  tried  to  spacing behavior on female movements monitoring utility  subseguent  created  of these assumptions  i n each  by  removing  into  the  and  manipulation  on a number of assumptions. i s that  were  t h e . vacated  completely  females. Animals missed may have prevented moving  females  movements of the surrounding animals. The  of t h i s design i s dependent  The f i r s t  assess the i n f l u e n c e o f  other  areas  f r e e of a d u l t females  a r e a . To reduce t h e chances o f t h i s  happening  the  removals were done i n areas o f highest  No  new animals were ever captured i n the middle of these a r e a s .  All  were caught on the outer edge and subsequent  telemetry  showed  that  they  spent  little  trapping  from  intensity.  monitoring  by  time i n the a c t u a l  TABLE 9 Home range use by Telemetry females f o l l o w i n g the second removal. Values represent the p r o p o r t i o n of l o c a t i o n s f o r each animal i n the h a l f of i t s home range nearest the removal a r e a . Pre-removal values were equal t o 0.50.  HARE NO. T2 T3 T5 T8 T9 T12 T13 T1 4 T16 T18 T2 0 T22 T23 no. animals showing increase  JUNE 20-31 (NS)  JULY 1-15(NS)  JULY 16-AUG 1*  0. 75 0.36 0. 42 0.71 0.39 0.75 0. 08 0.29 0. 50 0.33 0. 87 0.00 l  1. 00 0.90 0. 50 0. 70 0. 46 0. 54 0. 50 0.27 t 0. 60 0.57 0. 22 0.83  0.87 1.00 i 0.69 0.39 0.53 0.43 0. 50  4/12  7/12  7/11  NS - not s i g n i f i c a n t P > .05 * P < .025 * - l o s t radio c o n t a c t  I  0. 50 0. 65 0.70 1.00  105  TABLE  JO  Home range use by S.C.C. females f o l l o w i n g the second removal. Values represent the p r o p o r t i o n of l o c a t i o n s f o r each animal i n the h a l f of i t s home range nearest the removal area. Pre-removal v a l u e s were equal t o 0.50. HARE NO. S2 S3 S4 S5 S6 S7 S8 S9 no. animals showinq increase  JUNE 20-31 (NS)  JULY 1-15(NS)  JULY 10-AUG 1 (NS)  0.46 0.77 0.78 0.8 3 0.11 0.73 0.50 0.20  0. 50 0. 82 0.93 0. 42 0. 00 0.70 1. 00 0. 50  0.37 0.89 0. 38 0.63 0.75 i 1.00 0.45  4/8  4/8  4/7  NS - not s i q n i f i c a n t P > .05 i - l o s t radio contact  106  removal area. I t seems u n l i k e l y  then, that t r a p p a b l e females  at  l e a s t , were missed on the removal areas. However, t h e r e i s s t i l l the  p o s s i b i l i t y t h a t trap-shy animals remained. To determine i f  t h i s was t r u e a hare d r i v e s i m i l a r t o t h a t d e s c r i b e d by K e i t h e t a l . ( 1968 ) was conducted moved net.  p r i o r to  the  first  removal.  People  through the removal area attempting t o d r i v e hares i n t o a The d r i v e was conducted twice and no animals were captured.  F u r t h e r support f o r the c o n t e n t i o n t h a t no t r a p - s h y present  in  hares  were  the area ccmes from o b s e r v a t i o n s made while s e t t i n g  and checking the t r a p p i n g g r i d s . No unradio-tagged animals ever  sighted  on  S.CC.  where  a l l animals  received  c o l l a r s . U n f o r t u n a t e l y , some males on Telemetry were not and  so  one  radiotagged  c o u l d not be sure t h a t any animals without c o l l a r s  s i g h t e d t h e r e were females. The f a c t that none were S.C.C.  were  would  sighted  on  suggest t h a t a l l animals present on the t r a p p i n g  g r i d f o r any l e n g t h of time were captured. The second  assumption  i s t h a t the removal was done  at  the  a p p r o p r i a t e time. The e f f e c t of s p a c i n g behavior on movement may be more important at c e r t a i n times of the year. I chose the time period  just  p r i o r to b i r t h of the f i r s t  appear t o be most a g g r e s s i v e observed  that  at  this  l i t t e r because females  time.  Grange  ( 1932 )  females would not allow males near them p r i o r t o  p a r t u r i t i o n . Rongstad and T e s t e r ( 1971 ) suggested that snowshoe  hares  contract  female  the s i z e of t h e i r home range p r i o r t o  g i v i n g b i r t h . T h i s may be an attempt t o avoid other i n d i v i d u a l s . Haugen females  ( 1942 ) f e l t  that c o t t o n t a i l  were t e r r i t o r i a l  and H o l l e r  ( Sylyilagus  floridanus  )  during the breeding season and Harsden  ( 1964 ) obvserved some defence of nest s i t e s .  Hence  107  the  time  prior  experiment.  to  parturition  appeared  appropriate f o r t h i s  Spacing may a l s o be important a t other times o f year  and f u r t h e r experiments  will  be  necessary  to  examine  these  periods. The  third  assumption  i s t h a t the i n d i v i d u a l s removed were  representative,  in  of  population.  f o r example,  dominance  If  terms  hierarchy  social  status,  females  ( Lindlof  1978 )  were and  of  the  entire  organized only  into a  subordinate  animals were removed, r e s u l t s c o u l d be very d i f f e r e n t from  those  obtained i f dominant animals were removed. There i s no e f f e c t i v e way  of  determining i f t h i s d i d a c t u a l l y occur. However, a l l of  the females  removed  were  pregnant  and  showed  no  noticable  differences  i n body weight, c o n d i t i o n , or home range s i z e  from  other females i n the area. I f s o c i a l d i f f e r e n c e s d i d e x i s t ,  they  were not i n d i c a t e d by these f a c t o r s . The f i n a l assumption  i s that  telemetry  locations  give  a  reasonable estimate of home range l o c a t i o n and use. The accuracy of  the l o c a t i o n s has already been d i s c u s s e d . The d a i l y  schedule  of l o c a t i o n times was designed t o l o c a t e animals d u r i n g  periods  of  activity  and  resting,  thus  e l i m i n a t i n g any b i a s e s due t o  d i f f e r e n t i a l use of home range d u r i n g each behavior. locating  schedule  b i a s e s would  be  the  was not changed d u r i n g the study any unknown similar  before  and  conseguently would not have a f f e c t e d Females could have responded 1.  Since  after  t h e . removal  and  the r e s u l t s .  to the removal by:  I n c r e a s i n g t h e i r use of the vacated area by s h i f t i n g the  boundaries o f t h e i r home range. 2.  Immigrating  to  the removal  area from long d i s t a n c e s  108  (beyond the group of radio-tagged females) 3. S h i f t i n g use of t h e i r home range but  not  changing  the  a c t u a l boundaries. 4.  Showing no change i n t h e i r movements a f t e r the removal.  Females as a whole, d i d not i n c r e a s e t h e i r use area  following  each  of  the  of the two removals. Some i n d i v i d u a l s d i d  spend more time i n the area but none showed a major their  o l d home range t o the area l e f t  w e l l , no long d i s t a n c e immigrants came area. the  Females  shift  from  vacant by the removal. As to  occupy  the  removal  appear u n w i l l i n g t o s h i f t t h e i r home range d u r i n g  breeding season, a f i n d i n g s i m i l a r t o t h a t o f  Keith  removal  ( 1976 ) .  These  authors  reduced  Windberg  and  female d e n s i t y a t the  beginning of the breeding season i n two s u c c e s s i v e years. In the first,  a year o f i n c r e a s e , there was no replacement  breeding  season.  During  females  may  habitats.  This  suggests  be more mobile d u r i n g high numbers, p o s s i b l y  because of i n c r e a s e d s o c i a l i n t e r a c t i o n . I t appears though, the  the  the second, a peak year, females were  r e p l a c e d by i n d i v i d u a l s from adjacent that  during  normal i n t e r a c t i o n s between breeding females during  years a t l e a s t , a r e not s u f f i c i e n t t o  force  animals  that  increase to  shift  t h e i r home range t o unoccupied areas. T h i s r e s u l t i s important i n terms of answering the q u e s t i o n of  whether  behavior  can l i m i t hare breeding d e n s i t i e s . Watson  and Moss ( 1970 ) o u t l i n e four c r i t e r i a that must for  be  satisfied  t h i s to be t r u e . The most p e r t i n e n t t o t h i s study i s t h a t a  s u b s t a n t i a l p o r t i o n of  the p o p u l a t i o n  criterion  considered  i s usually  to  does be  not  breed.. T h i s  true i f vacant areas  c r e a t e d by e x p e r i m e n t a l removal o f breeding animals  are  filled  109  by  other  individuals  red  grouse  ( J e n k i n s e t a l . 1963  ( Krebs  et a l . 1976  Hares  which i n t u r n breed. T h i s i s the case i n ) and  in  Microtus  townsendii  ).  did not r e f i l l  vacated areas c r e a t e d by experimental  removal of females. T h i s suggests t h a t t h e r e were no  individuals  around t h a t c o u l d i n c r e a s e t h e i r f i t n e s s by  into  moving  those  areas. In other words, t h e r e were no i n d i v i d u a l s present but not breeding because is  negative  they d i d not have space t o do so. However, t h i s  evidence and as such i s open to a v a r i e t y of other  p o s s i b l e e x p l a n a t i o n s . The most obvious of removal  of  breeding  females  B e h a v i o r a l i n t e r a c t i o n s may going  to  breed  at  was  done  these at  is  the  wrong  have sorted out which  an e a r l i e r time. L o s e r s may  time. were  have died  soon  area. I f  one would expect t o see an abrupt drop i n  s u r v i v a l when t h i s b e h a v i o r a l o r g a n i z a t i o n occurred. T h i s detected  no  such  the  animals  a f t e r and so were not a v a i l a b l e to c o l o n i z e the removal t h i s were t r u e though,  that  drop.  Further  removal experiments  study  at other  times w i l l be the only method of determining i f t h e r e i s a breeding  non-  s u r p l u s of animals at some time during the year or the  c y c l e . The f a c t t h a t Windberg and K e i t h  ( 1976 ) d i d get animals  moving i n t o vacated areas i n a peak year suggests s u r p l u s may  that  such  e x i s t at t h i s time.  Although females d i d not respond  to the removal by  shifting  the l o c a t i o n o f t h e i r heme range they d i d a l t e r t h e i r a c t u a l of  of  use  t h a t range. I f females avoid c o n s p e c i f i c s , they would be  expected t o spend nearest  a  the  more time i n the p o r t i o n of t h e i r  removal  home  range  area and away from other females* T h i s i s  what a c t u a l l y o c c u r r e d . The f a c t t h a t S.C.C.  females showed no  110  s i m i l a r s h i f t s suggests that Telemetry females to the removal and not to some other unknown The  shift  pronounced  were  factor.  i n home range use by Telemetry  a f t e r the second removal.  responding  females was l e s s had  already  s h i f t e d a l a r g e p o r t i o n of t h e i r a c t i v i t y t o the removal  side of  t h e i r home ranges a f t e r t h e f i r s t then,  f o r the  actually  animals  moving  the  to  Many o f these  removal. I t would be d i f f i c u l t  shift  boundaries  activity of  their  even more without home  ranges.  As  p r e v i o u s l y p o i n t e d o u t , females were u n w i l l i n g t o do t h i s . To  conclude,  female  spacing behavior d u r i n g the breeding  season does not i n f l u e n c e the a c t u a l home  range.  and subseguent females  This  to  in  density  have  no  the removal experiment  suggests they u t i l i z e t h e i r home range interaction.  of  an  animal's  seems to be s e t p r i o r t o the breeding season  changes  responded  location  in a  effect.  However,  i n a manner which way  that  avoids  111  Is. EFFECT OF ft DOLT FEMALES ON  One  of  the  few  JUVENILE MOVEMENTS AND  common agreements among people working  s m a l l mammal p o p u l a t i o n  dynamics i s the  juvenile  changes i n p o p u l a t i o n  survival  Myers 1974;  survival  are  l a r g e l y unknown. K e i t h  social  from  summer  Survival of  As  a  and  1974  ),  in  first  they  feel,  which step  winter.  ground  ( R e d f i e l d et a l . 1978 I removed adult breeding  juvenile  is  season and  in  exist  by  the  has  not  been  t h i s d i r e c t i o n I examined movements  the  and  survival  Females have been shown t o  influence  squirrels  species  (Sherman  including 1977  )  and  pikas voles  ). females  from  an  area  durinq  the  late  monitored j u v e n i l e s on t h i s area as w e l l a  number  from s p e c i f i c hypotheses to be t e s t e d . They Females  and  survival,  determined  juveniles  on a c o n t r o l . T h i s experiment a l l o w s  1.  factors  to midwinter, on changes i n snowshoe  d i s p e r s a l of j u v e n i l e s i n a number of (Smith  of  the  woody browse i n winter. However, the e f f e c t o f  milieu  fall  However,  ) point to the i n f l u e n c e  i n f l u e n c e of a d u l t females on j u v e n i l e during  and  juvenile  numbers.  examined.  numbers (Krebs  ).  availability the  of  1978  (1978  on  influence  Windberg  particularly hare  on  important  K e i t h and  controlling Windberg  SURVIVAL  predictions  include:  f o r c e j u v e n i l e s to d i s p e r s e  a d u l t s . I f so t h i s would be  of  as  i n t o areas f r e e of  r e f l e c t e d by the  removal  area  having: (a ) fewer j u v e n i l e s (b ) g r e a t e r  r a t e s of  2.  affect  Females  dispersing ingress juvenile  survival  r a t e s . Rates then,  112  should d i f f e r between c o n t r o l and manipulation 3. Females i n f l u e n c e use of would  be  reflected  by  No d i f f e r e n c e s between  the  indicate  either  females  juvenile  survival  detected by my  and  area  juveniles  s h i f t i n g t h e i r home ranges  that  an  on  a f t e r the  removal  by  and  juveniles.. the  or  This  removal  area  manipulation. control  were unimportant  movements  areas.  that  areas  would  i n determining  changes  were  not  methods.  7. 1. Methods  Juveniles and  were  trapped  on the two  S.C.C. Animals having a weight  greater  r a d i o - t a g g e d and l o c a t e d twice d a i l y . Oct..  1st, 1978  study areas, than  500  g  were  Monitoring continued  until  a f t e r which animals were f o l l o w e d i n t e r m i t t e n t l y  with i n t e n s i v e l o c a t i n g p e r i o d s i n l a t e November 1978 February-March to Oct.  1,  1979.  1978.  l a t e November and On  August  Telemetry rates  and  Telemetry  G r i d s were trapped weekly from  and May  Traps were a l s o set once i n October,  1,  twice  late 1978 in  weekly i n March. 14,  1978  the  four  were removed by t r a p p i n g movements  of  or  adult  females present on  shooting.  a l l j u v e n i l e s caught  The  at l e a s t once on  e i t h e r g r i d before the removal were monitored  by  t e l e m e t r y . S.C.C.  control.  was  used as an experimental  survival  trapping  and  113  7.2.  Results  7,2-1. S u r v i v a l and  A The  total  Dispersl  of 32  j u v e n i l e s were equipped with r a d i o - c o l l a r s .  f a t e s of these animals a f t e r the  Table  11.  were no still  Sexes  were  removal  combined to i n c r e a s e  can  number  dying  on the  grids in  the  ( X ,P  > .05  2  animals  removal  were  ) . There was  not  different  higher  number  at  least  once  between g r i d s e i t h e r  some s u g g e s t i o n  l e a v i n g Telemetry was  in  g r i d , or number d i s p e r s i n g .  Also s u r v i v a l r a t e s of a l l animals l i v e - t r a p p e d before  seen  sample s i z e . There  s i g n i f i c a n t d i f f e r e n c e s between the two alive,  be  that  the  (6 vs 3 ) but  number small  of  sample  s i z e s prevented meaningful comparisons. The  number of new  removal  was  used  show t h a t the different and  animals caught on  two  of  ingressors  grids  ( X ,P 2  the s u r v i v a l r a t e or long to  distance  was  > .05  12 then, provide no evidence t h a t  early f a l l  grids  after  as a measure of i n g r e s s . R e s u l t s  number  on the  the  never  ). Results  adult  the  i n Table  12  significantly i n Tables  females  11  influence  movements of j u v e n i l e s  during  spring.  7.2-2. Changes i n Home Range  The  home  ranges,  j u v e n i l e s on  S.C.C.  before  after  and  and  as  determined  by  telemetry,  of  four j u v e n i l e s on Telemetry were  the removal. F i g s . 24 and  25 show that  five known there  TABLE 11  Fates of r a d i o - t a g g e d j u v e n i l e s caught on S.C.C. and Telemetry a t l e a s t once before removal of a d u l t females. F i g u r e s cover time p e r i o d from Aug 14-Mar 31 1979.  S.C.C..  TELEMETRY  NO. ALIVE ON GRID  6  5  NO. DISPERSING  3  6  NO. DYING ON GRID  7  5  16  16  TOTAL  TABLE 1 2  Number o f untagged animals captured on each g r i d a f t e r removal of adult females on Telemetry.  AUG14-OCT1/78  0CT1-DEC1/78  M  F  M  S.C.C.  12  11  4  TEL.  15  10  9  ______________—_______________  F  DEC1/78-MAR31/79 W  F  4  4  0  5  1  1  _______  __________________  116  Figure 24. Home ranges o f j u v e n i l e snowshoe hares on Telemetry showing no change i n l o c a t i o n before ( ) versus a f t e r (- - -) the removal o f a d u l t females. Home ranges of i n d i v i d u a l animals are not i n r e l a t i o n t o each other.  117  o5m  118  Figure 25. Home ranges of j u v e n i l e hares on S.C.C. showing no change i n l o c a t i o n before ( ) versus a f t e r (- - -) the removal of adult females on Telemetry. Home ranges o f i n d i v i d u a l animals are not i n r e l a t i o n t o each other.  119  85m  120  were  no  shifts  in  any  of  these  ranges  following  the  manipulation. A d d i t i o n a l l y , some knowledge of the whereabouts o f juveniles  caught  b e f o r e the removal but not r a d i o - t a g g e d c o u l d  be determined  by t r a p p i n g  radio-tagged  and  results.  subsequent  These  animals  were  monitoring showed t h a t t h e i r pre-  removal p o i n t s of capture were never o u t s i d e t h e i r home ranges. The  later  post-removal  above suggests that removal of a d u l t females on  Telemetry had no e f f e c t on movements of j u v e n i l e s i n t h a t area. However, changes i n the amount of o v e r l a p between j u v e n i l e s and may  a d u l t home ranges on S.C.C. have been o c c u r r i n g . F i g s .  locations  of  the  suggests that some i n t e r a c t i o n 26  and  t r a p p i n g g r i d s and  27  show  the  j u v e n i l e and adult  home ranges i n both study areas p r i o r to the removal. overlapped  adults  differences in relative  to  considerably  the the  located d i r e c t l y  location trapping  female  Juveniles  i n each case. There were major  of  adult  grids.  on the g r i d  relative  females'  Females  on  home  ranges  Telemetry were  while those on S.C.C.  spent  much  more time i n the surrounding area. T h i s s i t u a t i o n was  consistent  throughout  F i g . . 28  shows that  decreased s t e a d i l y  throughout  the  entire  breeding  j u v e n i l e - a d u l t o v e r l a p on S.C.C. late  August  and  September*  radio-tagged on  the  avoiding  occupied  areas  grid  it by  season.  As  more  appeared adult  and more j u v e n i l e s were as  females.  showed no s h i f t  i n home ranges to cause the  Juveniles  already  had  chosen  though  they  were  Again, t e l e m e t r y  decreased  overlap.  the unoccupied areas by the time  they were f i r s t r a d i o - t a g g e d . To summarize, survival  rates  or  there  were  movements  no  detectable  differences  between j u v e n i l e s on S.C.C.  in and  121  F i g u r e 26. R e l a t i v e l o c a t i o n s o f 5 a d u l t female ( ) and 5 juvenile ( - - - ) heme ranges on S.C.C.. The t r a p p i n g g r i d i s represented by the dark l i n e s . Notice the small proportion of adult ranges en the g r i d .  100  m  123  F i g u r e 2 7 . . R e l a t i v e l o c a t i o n s of a d u l t female ( ) and j u v e n i l e ( - - - j home ranges on Telemetry. The trapping grid i s represented cy the dark l i n e s . Notice the c e n t r a l l o c a t i o n o f a d u l t ranges r e l a t i v e t o the t r a p p i n g g r i d .  125  F i g u r e 28. Home ranges of 5 adult females ( ) and 10 (- - -) j u v e n i l e hares on S.C.C. showing low overlap throughout l a t e August and September. The t r a p p i n g g r i d i s represented by the dark l i n e s .  126  AUG 15-31  SEPT. 1 5 - 0 C T . 1  100 m  197o  1978  127  Telemetry a f t e r the removal of a d u l t females on Telemetry. suggests  that  adult  females  had  little  parameters. The s m a l l amount of o v e r l a p adults  on  S.C.C.  however,  influence  between  indicates  that  j u v e n i l e s might be determined by females  at  This  on these  juveniles the  a  and  l o c a t i o n of  time  prior  to  radio-tagging.  ,7» 3. . D i s c u s s i o n  Results  of  no d e t e c t a b l e during  the above experiment i n d i c a t e t h a t females had  e f f e c t on the s u r v i v a l and movements of  t h e l a t e breeding season. The p o s s i b l e reasons f o r t h i s  outcome w i l l now be d i s c u s s e d . above and  juveniles  conclusion  The f i r s t  of course, i s t h a t  i n c o r r e c t . Other f a c t o r s such as food  Windberg 1978 ) o r a d u l t male behavior  more important a t t h i s time. I t i s a l s o effects  may  become  more  important  the  (Keith  (Healey 1967 ) may be possible  during  p o r t i o n s o f the c y c l e . Removal experiments a t  that  female  peak  and d e c l i n e  this  time  would  i n d i c a t e whether t h i s i s so. Females times other  may  i n f l u e n c e j u v e n i l e movements each year but a t  than the  late  breeding  season.  In  many  mammals  weaning i s o f t e n a time when j u v e n i l e s are f o r c e d t o leave parents'  home  range  (Smith 1974 ) . In t h i s study the above i s  suggested by the f a c t that  j u v e n i l e s and a d u l t  S.C.C..  little.  overlapped  which i n i t i a l l y since  very  must have been  radio-telemetry  home range.  As  their  well,  these  ranges  Movements t o reduce  100%,  revealed  home  were  done  by  overlap, juveniles  that adults did not s h i f t  movements  had  to  on  occur  their before  128  juveniles  were radio-tagged as no tagged animals showed s h i f t s .  The p e c u l i a r S.C.C.  arrangement  of  adult  females  their  the  mothers' home range before they c o u l d be captured.  L a t e r monitoring by telemetry then, merely  revealed  that  they  not r e t u r n once they had l e f t . The  fact  that  home  ranges  of  the  two groups  d i s t i n c t suggests t h a t some i n t e r a c t i o n was late  fall.  Why  then,  did  occurring  j u v e n i l e movements?  juveniles  It  and  was  assumed  adults  had  that  prior  overlapping  then,  would  create  a  were  not.  j u v e n i l e s occupied removal,  However,  areas  juveniles  on  free both  a d u l t s . Therefore n e i t h e r group females were  in  the  important,  same  of  the on  both  where  interaction in  of  adult  females.  of  on  S.C.C,  F i g . 26, S.C.C.  in  was e x p e r i e n c i n g  prediction  the  Telemetry  but  shown  existed  removal,  females  as  grids  answer  After  differences  the  areas f r e e of pressure  area. As a r e s u l t , even i f adult  the  in  involved i n  adult  situation  j u v e n i l e s were f r e e frcm a d u l t female juveniles  to  ranges  experimental and c o n t r o l areas.. Removal Telemetry  even  The  be r e l a t e d t o one of the u n d e r l y i n g assumptions  the experiment.  remained  the e x p e r i m e n t a l r e s u l t s show t h a t  a d u l t females d i d not i n f l u e n c e may  to  t r a p p i n g g r i d c r e a t e d a s i t u a t i o n where j u v e n i l e s had t o  leave  did  relative  in  from  females juvenile  movements between the two g r i d s would not be born out. It  appears  then,  that  t h e q u e s t i o n of the importance o f  a d u l t females on j u v e n i l e s u r v i v a l and movement d u r i n q the and  winter  remains  unresolved.  mother's home ranqe a t weiqhts l e s s occupy  Some than  areas f r e e of adult females.,These  juveniles 500  g  leave and  fall their  come  to  two groups continue t o  129  exist  in  distinct  i n v o l v i n g removal season  of  areas  throughout  adult  females  the  earlier  fall. in  Experiments the  would provide answers as to whether j u v e n i l e s a r e f o r c e d  by females i n t o these vacant areas o r move on t h e i r own S i m i l a r l y , r e p l i c a t i o n of the experiment a  control  area  where  accord.  i n t h i s study, but with  the j u v e n i l e s overlapped a d u l t  would provide more c o n c l u s i v e evidence as t o the adult  breeding  females on j u v e n i l e s u r v i v a l and movement.  females,  importance  of  130  8.. SPACING BEHAVIOR AND  This  study  was  SNOWSHOE HARE POPULATION DYNAMICS  designed t o examine snowshoe hare s p a c i n g  behavior, an aspect of the animal's ecology which little  attention  and  has  received  c o u l d be important i n understanding  p o p u l a t i o n dynamics..Three guestions were posed  hare  at the o u t s e t o f  the study. They were:  1. What i s the s p a t i a l arrangement of  snowshoe  hare  home  ranges? Home  ranges  throughout  overlapped  extensively  between  and w i t h i n sexes  the year. Neither sex showed any type of  organization.  It  is  possible  that  a  territorial  dominance h e i r a r c h y i s  i n v o l v e d i n mate s e l e c t i o n and resource a l l o c a t i o n .  2. Is female spacing behavior d u r i n g important  in  determining  the  the  breeding  location  and  season use  of  location  of  n e i g h b o r i n g animal's home ranges? Changes i n d e n s i t y d i d not a f f e c t the adult  females.  home  range  Animals were u n w i l l i n g to s h i f t  from areas of high  overlap  to  areas  t h e i r home range  vacated  by  removal  of  breeding females. However, females d i d use t h e i r home range i n a manner t h a t seemed t o reduce i n t e r a c t i o n  3.  with neighbors.  Do a d u l t females i n f l u e n c e the movement and  survival of  juveniles? The answer to t h i s q u e s t i o n i s not c l e a r . results  suggested  that  adult  females'  Experimental had  no  removal  influence  on  131  j u v e n i l e s . However, t h e l a c k of adult  female  home  ranges  overlap  during  between  the f a l l  juvenile  suggests t h a t some  j u v e n i l e s leave t h e i r parent's home range t o occupy of  and  areas  free  a d u l t s . T h i s movement may occur p r i o r t o the time animals can  be r a d i o - t a g g e d . How do the above r e s u l t s r e l a t e t o snowshoe hare p o p u l a t i o n dynamics?  This  that attempt most  question  i s best examined i n l i g h t of t h e o r i e s  t o e x p l a i n the snowshoe hare cycle..The  prominent  o f these i s t h a t proposed snowshoe  hare  cycles  first  by K e i t h ( 1974 ) . He  hypothesized  that  interrelated  predator-prey i n t e r a c t i o n s . F i r s t l y ,  are caused  by  as hares  peak numbers they begin t o overbrowse t h e i r winter food This  overbrowsing  reduced  causes  damage  initiate  the hare  which have b u i l t up with r i s i n g point  t o speed  f o r the hares  results  hare  in  These  d e c l i n e . Predator p o p u l a t i o n s , hare  densities,  act at  this  up and extend t h e d e c l i n e phase. T h i s allows the  v e g e t a t i o n t o recover but predator numbers, which decrease lower  near  supply.  lower r a t e s of r e p r o d u c t i o n , a d u l t , and j u v e n i l e s u r v i v a l . to  two  t o the p l a n t s and r e s u l t s i n  p l a n t growth. Food shortage  combine  and  numbers  soon reach a p o i n t at which hare  with  densities  are allowed t o i n c r e a s e once more. The  key  interaction. possibly  to  Spacing  having  competition  Keith's  a  hypothesis  behavior  minor  f o r food.  If  during i n c r e a s i n g numbers )  role food  i s the  i s considered in  terms  In  other  words,  of  unimportant, intraspecific  s u p p l i e s were abundant  Keith's  hypothesis  t h a t s p a c i n g behavior should have l i t t l e location.  hare-vegetation  would  ( eg. predict  i n f l u e n c e on home range  i f i n d i v i d u a l s were removed, as i n  132  t h i s study,  there  should  i n d i v i d u a l s . R e s u l t s from  be  no  replacement  by  surrounding  t h i s study are i n accordance  with  this  prediction. An which  alternative incorporates  snowshoe  hare  hypothesis behavior  population  to  as  t h a t of K e i t h would be  an  important  dynamics.  Watson  o u t l i n e a h y p o t h e s i s whereby spacing densities  by  preventing  seme  component  and  behavior  limits  ( 1970  that  numbers  breeding  considered  in  limited  this  at  a  time  other  d e c l i n e phases of the  ( 1967  Watson still  than  and  exists  the  one  study. Perhaps t h i s occurs during a season  other than t h a t s t u d i e d here or p o s s i b l y  Another  should  with animals t h a t otherwise would not  ) h y p o t h e s i s . However, the p o s s i b i l i t y were  )  i n d i v i d u a l s from breeding. T h i s  have bred. R e s u l t s of t h i s study do not support the Moss  in  Moss ( 1970  hypothesis would p r e d i c t t h a t removal of breeding females be f o l l o w e d by replacement  one  only  during  peak  or  cycle.  behavior  hypothesis  ) which a l s o contends  is  that  proposed  by  Chitty  t h a t numbers are l i m i t e d by s p a c i n g  behavior. C h i t t y goes on to p o i n t  out  that  this  behavior  is  under g e n e t i c c o n t r o l and s u b j e c t to r a p i d s e l e c t i o n . T h i s means that  during  increasing  numbers  l e s s a g g r e s s i v e genotypes are  f a v o r e d while i n d e c l i n e phases a g g r e s s i v e advantage.  One  of  indivduals  gain  the p r e d i c t i o n s of the C h i t t y hypothesis i s  t h a t spacing behavior w i l l be l e s s i n t e n s e during i n c r e a s i n g compared  to  declining  p o s s i b l y e x p l a i n why created  by  the  an  as  p o p u l a t i o n s ( Krebs 1978b ). T h i s could  females  experimental  were  not  removals  forced  into  the  i n t h i s study.  area  Similar  removals d u r i n g peak and d e c l i n e phases of the c y c l e are needed.  133  Work has shown t h a t j u v e n i l e important  to  the  population  K e i t h hypothesis contends brought  survival  dynamics  that  changes  and  movements  of snowshoe hares. in  these  suggest  that  remains  unresolved.  Results  The  factors  about by changes i n food a v a i l a b i l i t y . The  spacing behavior  are  are  i n f l u e n c e of  in  this  study  seme j u v e n i l e s l e a v e t h e i r parent's home range to  occupy areas f r e e of a d u l t s . Questions s t i l l remain mechanism  that  causes  these  experience  survival rates similar  as  to  the  movements and whether d i s p e r s e r s to  those  individuals  which  remain i n t h e i r parent's home range..Windberg and K e i t h ( 1976 postulated  that  juveniles  dispersing  during peak and d e c l i n e  years were f o r c e d to l e a v e t h e i r i n i t i a l home range intraspecific  because  increase  supplies  by L i d i c k e r  adeguate.  As  d i s p e r s a l might be a matter during  increase  pointed of  out  choice  rather  than  when  Deciding thorough lifetime.  food  by C h i t t y  ( 1967  )  necessity  years. A l t e r n a t i v e l y , juvenile d i s p e r s a l  the c y c l e i n a manner proposed  to  ( 1975  be a f u n c t i o n of a d u l t aggressiveness which changes with of  of  c o m p e t i t i o n f o r food. However, i t i s d i f f i c u l t  b e l i e v e t h a t t h i s occurs during p e r i o d s of are  )  might phases  ).  between these a l t e r n a t i v e e x p l a n a t i o n s r e q u i r e s a  knowledge of an i n d i v i d u a l ' s movements  throughout  S t u d i e s of d i s p e r s a l to date have been hindered by  its the  f a c t t h a t the whereabouts of an i n d i v i d u a l are unknown f o r l a r g e portions is of  of i t s l i f e t i m e . In the case of snowshoe hares n o t h i n g  known about i n d i v i d u a l movements between b i r t h and first  trapping.  movements may technigues,  As  suggested  occur during t h i s  time  by  this and  the  study,  because  time  important of  present  go unnoticed. These, as w e l l as l a t e r long d i s t a n c e  134  movements must be taken i n t o  account  if  the  d i s p e r s a l t o p o p u l a t i o n dynamics i s to be To  behavior  and  its  need  relation  of the s p a t i a l o r g a n i z a t i o n of hares  for  relationship  continued of  work,  behavior  to  especially  in  during the study f i t the  the  hypothesis  Keith  ( 1974  a l t e r n a t e hypotheses l i m i t s numbers  )  more  the  terms  of  survival.  predictions  closely  than  they  ( Watson and  Moss 1970  ).  However,  it  must  t h a t t h i s work examined behavior during only one  spacing  behavior  d e c l i n e years and  the  of do  i n c o r p o r a t i n g behavior as a mechanism which  (increase) of the snowshoe hare c y c l e . that  to  and p o i n t s t o  j u v e n i l e movements and  R e s u l t s of experiments  stressed  investigation  p o p u l a t i o n dynamics. 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