Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

The effects of social experience on play and agonistic behavior in the golden hamster and the Mongolian… Skirrow, Margaret Helen Wort 1965

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1965_A6_7 S57.pdf [ 3.24MB ]
Metadata
JSON: 831-1.0104778.json
JSON-LD: 831-1.0104778-ld.json
RDF/XML (Pretty): 831-1.0104778-rdf.xml
RDF/JSON: 831-1.0104778-rdf.json
Turtle: 831-1.0104778-turtle.txt
N-Triples: 831-1.0104778-rdf-ntriples.txt
Original Record: 831-1.0104778-source.json
Full Text
831-1.0104778-fulltext.txt
Citation
831-1.0104778.ris

Full Text

THE E F F E C T S OF SOCIAL. E X P E R I E N C E ON P L A Y AND A G O N I S T I C B E H A V I O U R I N T H E 1 G O L D E N H A M S T E R ' A N D THE M O N G O L I A N ^ G E R B I L b y M a r g a r e t H e l e n W o r t S k i r r o w B. S c . , 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 , 1 9 6 4 A t h e s i s s u b m i t t e d i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r t h e d e g r e e o f M a s t e r o f S c i e n c e i n t h e D e p a r t m e n t o f Z o o l o g y We a c c e p t t h i s t h e s i s a s c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE U N I V E R S I T Y OF B R I T I S H C O L U M B I A S e p t e m b e r , 1 9 6 5 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that per-mission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives,, It is understood that copying or publi-cation of this thesis for financial gain shall not be allowed without my written permission. Department of fi The University of British Columbia Vancouver 8, Canada Date H M Q l X i ABSTRACT To determine the effects of d i f f e r e n t s o c i a l conditions on play and agonistic behaviour, 25-day old golden hamsters and Mongolian g e r b i l s were divided Into four groups which d i f f e r e d with respect to s o c i a l experience aft e r weaning. Every day, from 26 to 6 l days of age, the young hamsters xvere observed f o r num-bers' and durations of fight-type interactions i n a l£-minute period. Every t h i r d or s i x t h day from 27 to 60 days of age, the ge r b l l s were s i m i l a r l y tested. Seven to i i i percent of play f i g h t s between hamsters i n -volved more than two animals simultaneously. Communally reared hamsters mixed with strangers played with strangers 71 percent of the time, while 90 percent of r e a l f i g h t s involved strangers. Neither of these measures involved the effects of e a r l y s o c i a l experience. I s o l a t i o n causes e a r l i e r cessation of play and e a r l i e r onset of r e a l f i g h t s i n golden hamsters. I s o l a t i o n also leads to a s i g n i f i c a n t increase i n the amount of play and r e a l f i g h t i n g i n these animals. Gerbils raised i n i s o l a t i o n with a toy show s i g n i f i -c a n tly more play than do gerb i l s reared under d i f f e r e n t s o c i a l conditions. Gerbils reared communally with the mother f i g h t s i g -n i f i c a n t l y more with strangers than they do with familar animals, and f i g h t s i g n i f i c a n t l y more than do animals reared communally with s i b l i n g s , or i n i s o l a t i o n with or without a ping pong b a l l . i i T A B L E OP CONTENTS Page I N T R O D U C T I O N 1 PROCEDURE k A. T h e E x p e r i m e n t a l A n i m a l s k B. E x p e r i m e n t a l C o n d i t i o n s 5 C. E x p e r i m e n t a l P r o c e d u r e 10 D. C r i t e r i a f o r D i s t i n g u i s h i n g P l a y a n d R e a l F i g h t s . 1!L R E S U L T S 16 A . P l a y F i g h t i n g V e r s u s R e a l F i g h t i n g l 6 1. T h e e f f e c t o f t h e m o t h e r l 6 2. A b s e n c e o f t h e m o t h e r 18 3. T h e e f f e c t o f t o y s 21 II. T h e e f f e c t o f t o t a l i s o l a t i o n 23 B. C r i t e r i a f o r D i f f e r e n t i a t i n g P l a y a n d R e a l F i g h t s . 25 1. L e n g t h s o f i n d i v i d u a l i n t e r a c t i o n s 25 2. L a t e n c i e s t o i n t e r a c t 26 3. N u m b e r o f a n i m a l s i n v o l v e d i n p l a y 27 4. S o u n d s u t t e r e d d u r i n g i n t e r a c t i o n s 28 0. C h o i c e o f P a r t n e r f o r I n t e r a c t i o n 28 1. P l a y f i g h t i n g 28 2. R e a l f i g h t i n g 28 D. L i t t e r S i z e s 29 D I S C U S S I O N 30 SUMMARY AND C O N C L U S I O N S I4.0 L I T E R A T U R E C I T E D ij.2 A P P E N D I X 4 5 i i i LIST OF APPENDICES Appendix No. Page 1. Analysis of variance f o r the determination of between treatment and between test s i t u a t i o n significance f o r hamsters and ge r b i l s k$ i v LIST OP TABLES Table Ho. Page 1. Ages of cessation of play and onset of r e a l f i g h t i n g f o r hamsters and g e r b i l s raised under d i f f e r e n t s o c i a l conditions and tested under d i f f e r e n t situations l\h 2. Differences between groups and test situations f o r play and r e a l f i g h t i n g i n hamsters I4.7 3. Differences between groups and test situations f o r play and r e a l f i g h t i n g i n g e r b i l s . . I4.8 V LIST OP FIGURES Figure No. Page 1. Arrangement of hamsters i n the experimental s o c i a l conditions i|9 2. Arrangement of ger b i l s i n the experimental s o c i a l conditions 5 ° 3. Play and r e a l f i g h t i n g between the mother and young hamsters 51 ]+. Average number of interactions between gerbil s raised with the mother 52 a. Between young i n the home cage. b. Between young i n the arena. c. Between strangers i n the arena. d. Between mother and young i n the home cage. 5. Number of interactions between ge r b i l s raised i n i s o l a t i o n 53 a. Between gerbi l s raised with toys. b. Between Kaspar Hauser g e r b i l s . 6. D i s t r i b u t i o n of durations of play fi g h t s i n infant hamsters 54 7- D i s t r i b u t i o n of durations of play and r e a l f i g h t s i n ge r b i l s 55 a. D i s t r i b u t i o n of r e a l f i g h t s i n juvenile g e r b i l s . b. D i s t r i b u t i o n of r e a l f i g h t s i n adult g e r b i l s . c. D i s t r i b u t i o n of play i n infant g e r b i l s . d. D i s t r i b u t i o n of play i n juvenile g e r b i l s . 8. Average number of play and r e a l f i g h t s following latency periods 56 a. Play i n hamsters. b. Real f i g h t s i n hamsters. c. Play i n g e r b i l s . d. Real f i g h t s i n g e r b i l s . ACKNOWLEDGEMENTS The author wishes to express her g r a t i t u d e to Dr. H F i s h e r f o r h i s valuable advice and encouragement, to Dr. J . P Eisenberg f o r h i s help i n i n i t i a t i n g the study, and to Dr. J . Be n d e l l f o r h i s c r i t i c a l reading of the manuscript. I am very g r a t e f u l to Susan Smith f o r her help i n gatheri n g the data. INTRODUCTION 1 A number of studies have shown that environmental factors may have profound e f f e c t s on the immature mammal, modi-fying the future behaviour and phy s i o l o g i c a l c a p a b i l i t i e s of that mammal (Bingham and G r i f f i t h s , 1952; Beach and Jaynes, 195^5 S e i t z , 195I4.; 1959; Melzack and Thompson, 1956; King, 1958; King and El e f t h e r i o u , 1959; Denenberg, 1962; Rosen and Hart, 1963). E a r l y s o c i a l experience affects many aspects of adult behaviour, including mating behaviour of the male rat and mouse (Beach, 1952; Kagan and Beach, 1953; King, 195&), learning (Luchins and Porgus, 1955) aricl aggression (Ginsburg and Allee, 194 2 ; H a l l and Kle i n , 19i|2; Seward, 19l}-5; Kahn, 195^; King and Gurney, 195^4-,* King, 1956; 1957; Levine, 1959; Denenberg, Hudgens and Zarrow, 196I4.). Certain investigators also have studied s t r a i n or sub-s p e c i f i c differences i n the effects of early experience on the behaviour of the adult organism (King, 1957; King and Eleftheriou, 1959; Rosen and Hart, 1963). These workers have attempted to choose strains which d i f f e r noticably i n aspects of t h e i r adult behaviour. Diet e r l e n (1959) stated that experience plays a role i n the development of f i g h t i n g behaviour i n the golden hamster, but he did not investigate the effects of early experience on adult behaviour. Wort (196^) went further by investigating the effects of d i f f e r e n t s o c i a l environments aft e r weaning on aggression i n these animals. She found that d i f f e r e n t types of s o c i a l environ-ment appear to influence the time of onset and amount of 2 aggression shown. Play behaviour has been studied by several workers (Meyer-Hoizapfel, 1956; Rowell, I 9 6 I ; Wort, I96J4.), and c e r t a i n c r i t e r i a f o r the d i f f e r e n t i a t i o n of play and r e a l f i g h t i n g i n the golden hamster have been suggested (Dieterlen, 1959; Rowell, I 9 6 I ; Wort, 196it). Wort (I96J4.) found that s o c i a l experience afte r weaning appeared to a f f e c t the age of cessation of play, and the amount of play indulged i n by young golden hamsters. Play f i g h t i n g i s a c h a r a c t e r i s t i c phenomenon i n both young golden hamsters and young g e r b i l s . A good account of the play f i g h t s of gerbi l s has been given by E i b l - E i b e s f e l d t (1951). Be-cause both these rodents show easily-distinguished play behaviour, and because the adult s o c i a l l i v e s of these animals are very d i f f e r e n t ( E i b l - E i b e s f e l d t , 1951; Dieterlen, 1959), i t was thought p r o f i t a b l e to compare the e f f e c t s of s i m i l a r early s o c i a l experience on the l a t e r adult behaviour of these species. The purpose of t h i s study was to determine whether di f f e r e n t s o c i a l environments after weaning have any effects on the age of cessation of play, and the amount of.play shown af t e r weaning by both young golden hamsters and young Mongolian g e r b i l s . It was hoped that both environmental and species differences might appear. The influence of d i f f e r e n t s o c i a l environments on the age of onset of r e a l f i g h t s and the actual amount of f i g h t i n g was also investigated f o r these species, i n the hope that both environmental and species differences might appear i n this type of behaviour also. The effects were tested by placing animals 3 from the d i f f e r e n t types of s o c i a l groups i n a n e u t r a l arena w i t h o t h e r animals r e a r e d under s i m i l a r c o n d i t i o n s , and a l s o by ob-s e r v i n g animals from communal groups i n t h e i r home cages or the n e u t r a l arena. The number of p l a y and r e a l f i g h t s i n d u l g e d i n by these animals were reco r d e d i n o r d e r to determine the l e v e l s of p l a y and a g g r e s s i o n shown by the animals of d i f f e r e n t s p e c i e s or o f d i f f e r e n t s o c i a l environments. PROCEDURE A. The Experimental Animals The Syrian golden hamster, Mesocricetus auratus, i s a small rodent of the family Cricetidae, subfamily Cricetinae. Domestic golden hamsters are descended from a female and her l i t -t e r of twelve young which were captured i n Syria i n 1930 (Bruce and Hindle, 1931+; Bond, 1<})L\S). Their common name i s derived from the German verb "hamstem" - to hoard, due to t h e i r habit of storing food i n t h e i r burrows. The golden hamster i s s o l i t a r y except for the f i r s t few weeks of l i f e , at mating, and when the female i s nursing her young (Rowell, 1961). The gestation period i s l 6 days, and l i t -ters may vary from one to seventeen young, although the usual range i s from f i v e to nine. The pups, which are born blind, f i r s t open t h e i r eyes a f t e r about two weeks. They are weaned from 21 to 25 days of age. Once the eyes are open, the young p a r t i c i p a t e i n "mock" or play f i g h t i n g with one another u n t i l approximately the t h i r -t i e t h day, when f i g h t i n g becomes more serious (Dieterlen, 1958; Rowell, I 9 6 I ) . Dieterlen (1958) noted that tooth gnashing, f l i g h t , and c e r t a i n other aspects of adult " r e a l " f i g h t i n g were missing from play interactions. Play f i g h t i n g l a r g e l y occurs i n young animals, while r e a l f i g h t s are engaged i n generally by adults. The Mongolian g e r b i l , Meriones unguiculata. i s a small rodent s i m i l a r i n size to the golden hamster. I t i s also a mem-ber of the family Cricetidae, but i s c l a s s i f i e d i n the subfamily 5 G e r b i l l i n a e . The genus, Meriones, i s found i n Asia, eastern Europe, and northern A f r i c a (Simpson, 1945)• The s o c i a l behav-iour of most of the species of Meriones i s very s i m i l a r (Eisenberg, pers. comm.). In the wild, Meriones are highly s o c i a l . Male and female remain together compatibly, even when the young are born. It i s possible to keep these animals i n large groups when i n cap-t i v i t y , f o r they f i g h t very l i t t l e . However, a stranger i n t r o -duced to a p a i r or group may be attacked (E i b l - E i b e s f e l d t , 1951)• The gestation period of these animals i s twenty-two days, with l i t t e r s averaging four young. The pups are born b l i n d and open t h e i r eyes at about 17 days of age. They are weaned at approximately 25 days. E i b l - E i b e s f e l d t (195D reports that play f i g h t i n g be-gins at 26 days and continues u n t i l J4.5 days of age while r e a l f i g h t s are more c h a r a c t e r i s t i c of older animals. B. Experimental Conditions Two hundred sixteen young golden hamsters, descendents of departmental stock, were raised under conditions of reversed l i g h t cycles, twelve hours of l i g h t being followed by twelve hours of darkness. The animals are nocturnal, and to take advan-tage of t h i s , the dark period occurred from 8:30 a.m. to 8:30 p.m. Thus data could be taken during normal working hours. The adult females were mated by introducing simultan-eously a male and female i n a neutral arena. The females and t h e i r r e s u l t i n g l i t t e r s were housed i n galvanized cages 6 ( 7 x 1 0 x 7 inches) with sawdust f l o o r covering. The animals were fed Buckerfield's Ration p e l l e t s every day, and fresh l e t -tuce every two days. Ample water was supplied i n glass water bottles with glass or metal nipples. The females were checked every day f o r the b i r t h of pups, and the young were said to be one day old on the day following p a r t u r i t i o n . When the young were 2 5 days old, they were assigned to one of four experimental groups, each group then l i v i n g under one of four d i f f e r e n t s o c i a l conditions. These conditions were: Group A: Mother plus l i t t e r . When the pups were 2 5 days old, two mothers and t h e i r l i t t e r s of four young were housed separately i n two large wire mesh cages ( 2 2 x 2 0 x 1 3 inches). The pups were kept past weaning with the mother because Dieterlen ( 1 9 5 9 ) believes that, i n the wild, the young would nor-mally remain with the mother u n t i l a l a t e r time. Shredded paper towels were provided f o r bedding material. Each set of two mothers and t h e i r l i t t e r s was designated a 'subgroup'. There were nine of these subgroups as i l l u s t r a t e d i n Figure 1 . Group B: L i t t e r minus mother. Two l i t t e r s consisting of four young were housed separately i n large wire mesh cages ( 2 8 x 1 3 x 9 inches). The mother was removed from each l i t t e r when the young were 2 5 days old. This condition was chosen because Rowell ( 1 9 6 1 ) believes that, i n the wild, the mother would leave the young at weaning to es t a b l i s h a nest else-where. Bedding was shredded paper towels. The arrangement of subgroups i s shown i n Figure 1 . 7 Group G: One pup plus a toy. T h i r t y - s i x young hamsters were housed separately i n galvanized cages (7 x 10 x 7 inches) with wire mesh tops. A table tennis b a l l was included i n each cage, while sawdust l i t t e r was provided. Pour of these animals were tested together per te s t day. Animals were i s o l a t e d with manipulable objects i n order to test the effects that s o c i a l play with an inanimate object has on adult s o c i a l behaviour. Group D: Kaspar Hauser animals ( t o t a l i s o -l a t e s ) . T h i r t y - s i x hamsters were housed separately i n cages l i k e those used i n condition C, but no toys were included. Pour of the Kaspar Hausers were tested together on each test day. A con-d i t i o n of t o t a l i s o l a t i o n was chosen to test the effects of a lack of s o c i a l i n t e r a c t i o n after weaning on post-weaning play and aggression. This condition might exist i n the wild i f , as Rowell (1961) believes, the mother l e f t the young at weaning, and i f the young i n turn dispersed. Figure 1 shows the arrangement of ham-sters i n Groups C and D. Cages were cleaned at l e a s t once every two weeks. The animals were handled only at these times, and care was taken that the animals were disturbed as l i t t l e as possible. Hamsters were fur clipped f o r i d e n t i f i c a t i o n purposes. Wherever possible, the sex r a t i o was kept constant (2 females : 2 males) i n each subgroup. Eighteen young Mongolian g e r b i l s , descendents of depart-mental stock, were raised under conditions s i m i l a r to those of the 8 hamsters, although fourteen hours of l i g h t were followed by ten hours of darkness i n an e f f o r t to induce the adults to breed. The dark period occurred from 8:30 a.m. to 6:30 p.m. as these animals also are nocturnal. The adult females were extremely d i f f i c u l t to breed, possibly because the stock was well over one year old. Some suc-cess was achieved by setting up pairs of ge r b i l s i n large wood and glass cages (36 x 2\+ inches) with sloping roofs. Floor cover-ing was a mixture of sawdust and very fi n e aquarium sand (Delmonte E i - 3 0 ) . The sand was necessary i n order that the animals could sand bathe. Sand bathing i s c h a r a c t e r i s t i c of Meriones. The animals coats become o i l y , and i t i s thought that sand bathing helps keep t h e i r coats clean. Nest material of non-absorbent cot-ton batting was provided. When l i t t e r s were born, the mother and her l i t t e r were removed from the large cage and were placed i n smaller, glass-sided cages (10 x l6 x 7 i inches) with wire mesh roofs. Food and water was provided as f o r the hamsters, but a supplement of sun-flower seeds and m i l l e t was given once per week. When the young were twenty-five days old, they were assigned to one of four experimental groups l i k e those of the ham-sters. These groups were: Group A: Mother plus l i t t e r . When the pups were 25 days of age, two mothers and t h e i r l i t t e r s of two pups each were housed separately i n large wood and glass cages (36 x 2i|. inches) with sloping roofs. The substrate used consisted of a 9 h a l f sand, h a l f sawdust mixture with cotton batting as nesting material. There was only one subgroup i n this condition as only two mothers had l i t t e r s born on the same day. The smaller l i t t e r consisted of two pups; the larger, of three. Thus two was chosen as the number of pups to be used per mother i n th i s group and i n other groups. Figure 2 shows the arrangement of animals i n this and following groups. Although i t i s possible that the father remains with the mother and l i t t e r i n the wild, he was removed and the mother alone was allowed to rear the young i n order to approximate as c l o s e l y as possible the hamster s o c i a l s i t u a t i o n . A l l four experi-mental conditions were chosen to s i m i l a r l y approximate the experi-mental situations used f o r the hamsters. Group B: L i t t e r minus mother. Conditions i n thi s group were s i m i l a r to those i n Group A, except mothers were not included. Only one subgroup was used. Group 0: One young g e r b i l plus a toy. Six young animals were housed separately i n i n d i v i d u a l glass cages (10 x l 6 x 1% inches) with wire mesh tops. The young were v i s -u a l l y i s o l a t e d by pasting paper towels to the outside of the cage walls. A table tennis b a l l was included i n each cage. Two of these animals were tested together per test day. Group D: Kaspar Hauser animals (tot a l i s o -l a t e s ) . Four g e r b i l s were housed i d e n t i c a l l y to those i n Group C, but no toys were included. Two Kaspar Hausers were tested together per test day. 10 Cages were cleaned once per month, and the animals were handled only at these times. The young g e r b i l s were fur clipped f o r i d e n t i f i c a t i o n . The sex r a t i o was one female : one male wherever possible. C. Experimental Procedure A neutral arena measuring 36 x 2l\. x 36 inches was used to test the numbers of play and re a l f i g h t s engaged i n by the animals raised under a l l four experimental conditions. The arena was constructed of heavy plywood with a glass front. The f l o o r was covered with dry garden s o i l , and a few food p e l l e t s were scattered on the substrate. Each day from 26 to 6 l days of age, four hamsters from the group with toys, and the Kaspar Hausers were observed f o r 15 minutes i n the arena. A 'subgroup' of the hamsters kept with t h e i r mothers and those of si b l i n g s only consisted of two cages of experimental animals (Figure 1 ) . The pups from one cage were observed f o r 15 minutes i n the arena, 15 minutes i n the home cage, and i n mixed groups consisting of two animals from each cage. This l a s t set of observations was made f o r 15 minutes i n the neu-t r a l arena. The observations made on the animals of one cage were repeated on those of the second cage. Thus data were ob-tained during one and one-half hours actual recording time. A 'subgroup' of hamsters was tested only every ninth day. It was hoped that by so doing the animals from the group with toys and the Kaspar Hausers would not learn to associate the testi n g arena with periods of "companionship" (King, 1958) . 11 There i s nothing i n the data that would f i t a hypothesis that the animals did associate the arena with "companionship". Every s i x t h day from 21 to 57 days of age, gerbi l s from both the group raised communally with the mother and the group raised communally with sibs were tested by the same method as that used to test the communally raised hamsters. Because there was only one subgroup i n both these conditions, testing was done every s i x t h day i n order to obtain as much data as possible without allowing the animals to become f a m i l i a r with the testing method (King, 1958). The animals from the group kept with toys were tested every t h i r d day from 27 to 60 days by observing two animals i n the arena f o r 15 minutes. Because there were s i x animals reared under th i s condition, an animal was exposed to t e s t i n g every nine days. Kaspar Hauser animals were observed on days 27, 30, 36, 39, h£>, k&> Sk-> a^d 57* Two animals were tested every nine days, but as only four animals were reared as Kaspar Hausers, there are gaps i n the s e r i e s . During testing, the c e l l i n g l i g h t was turned o f f . A low i n t e n s i t y red l i g h t near the arena or home cage supplied the only i l l u m i n a t i o n . Observations were made under red l i g h t to reduce the p o s s i b i l i t y of the animals being aware of the observer (Eisenberg, 1962). The te s t animals were introduced nearly simul-taneously into the arena by depositing the animals i n opposite corners v i a a trough-shaped cardboard box. As soon as a l l animals 12 were i n the arena, data were taken f o r 15 minutes on a P h i l i p s tape recorder. Home cage data were taken f o r 15 minutes when the animals were active i n the cage. The number and durations of i n d i v i d u a l play and r e a l f i g h t s were recorded during the te s t period. In mixed groups, the p a r t i c i p a t i o n by litter-mates or strangers i n play and f i g h t -ing was noted. Other items of i n t e r e s t were also noted. When the data were transcribed, the durations of single interactions were timed to o n e - f i f t h of a second by use of a stop-watch. However, 'interactions' lengths were rounded to the near-est second f o r the purpose of ca l c u l a t i o n . The latency to i n t e r -act, which i s the time from introduction to the beginning of the f i r s t i n t e r a c t i o n , was also recorded, and was rounded to the near-est minute f o r calcul a t i o n s . Analyses of variance were performed on the number of play and r e a l f i g h t s from cessation of play and onset of r e a l f i g h t i n g f o r both hamsters and g e r b i l s . A l l four experimental conditions were compared, as were the three d i f f e r e n t test s i t u a -tions (home cage, arena, mixed) f o r the communally raised hamsters and g e r b i l s . Analysis of variance V (Appendix 1) was performed using a s-quare root transformation because of the misleadingly large amount of variance shown by the ge r b i l s reared with toys. If an analysis of variance showed s i g n i f i c a n t difference due to treatment, further tests were made to determine the p a r t i c u l a r treatments causing this e f f e c t . A Tukey's test f o r d i f f e r e n t sam-ple sizes was performed and significance between treatments was 13 determined. Thus i t was determined i f the average number of play or f i g h t interactions per 15 minute period f o r a p a r t i c u l a r ex-perimental group or testing s i t u a t i o n was s i g n i f i c a n t l y d i f f e r e n t from that shown by any other group or test s i t u a t i o n . In order to determine the average length of play f i g h t s p r i o r to weaning, young hamsters and gerbils between the ages of l6 and 2i|. days were observed i n th e i r home cages. This was done so that a comparison between the average length of play f i g h t s i n weaned and infant g e r b i l s could be made, and a d i s t r i b u t i o n of the lengths of play f i g h t s i n infant hamsters could be determined. In order to compare the average length of a r e a l f i g h t i n juvenile (the experimental) gerbils and f u l l y adult animals, encounters were staged between adults of the breeding stock. The animals were over one year old at the time. The animals were introduced into the te s t i n g arena and were observed f o r 15 minutes. Dieterlen (1959) states that during play f i g h t i n g , only two hamsters are engaged i n any one in t e r a c t i o n . As the infant pups were being observed, i t became evident that three pups often play fought together. Therefore the number of play f i g h t s i n which more than two animals were engaged at any one time were recorded f o r both infant and juvenile hamsters. Attempts were made to record any sounds uttered by In-fant g e r b i l s as they played. A P h i l i p s tape recorder coupled to a t r a n s i s t o r i z e d amplifier was used, and recordings were made while the pups were engaged i n play f i g h t i n g . Spot checks were made to determine whether the animals raised with a toy were playing with the table tennis b a l l . When l i t t e r s were bom, the number of pups was recorded to determine the average l i t t e r size of both hamsters and g e r b i l s . D. C r i t e r i a f o r Distinguishing Play and Real Fights Wort (196!|J chose three c r i t e r i a and suggested a fourth f o r d i f f e r e n t i a t i n g play and r e a l f i g h t s i n hamsters. These four c r i t e r i a were used i n t h i s experiment. They were: 1. Position: In play f i g h t i n g , the animals wrestle b e l l y to b e l l y , while i n r e a l f i g h t s , other positions such as b e l l y to back or side are used often. 2. Role r e v e r s a l : In play f i g h t i n g , there i s continual role reversal. One animal plays "aggressor", then "victim", then "aggressor", etc. In r e a l f i g h t s , role reversal does not occur. 3. B i t i n g : Bites do not occur i n play f i g h t -ing, whereas they occur i n nearly every r e a l f i g h t . if. The post-fight chase: Wort (1961|.) found that 7 0 percent of r e a l f i g h t s were followed by an immediate chase. No play f i g h t s were concluded with a chase. E i b l - E i b e s f e l d t (1951) has described i n d e t a i l both r e a l and play f i g h t i n g i n a species of g e r b i l much l i k e the Mongolian g e r b i l . A number of c r i t e r i a may be used to d i s t i n g u i s h play and r e a l f i g h t i n g i n these animals. The most useful of these are: 1. Prologue: A play f i g h t i s preceded by a short s o c i a l period of leaping against one another and nibbling the f u r . This i s absent from r e a l f i g h t s . 15 2. Position: The animals wrestle together i n a b e l l y to b e l l y position, drumming at one another with t h e i r hind feet. In r e a l f i g h t s , numerous other positions are used. 3. B i t i n g : B i t i n g i s confined to s o c i a l nibbling of the fur i n play f i g h t i n g . Severe nips and bites often occur i n r e a l f i g h t i n g . Ii. Missing elements: Certain elements com-mon i n r e a l f i g h t s are missing from play f i g h t s . These are: high pitched squealing, drumming the hindfeet on the substrate, and t a i l - r a t t l i n g . RESULTS 1 6 A. Play Fighting Versus Real Fighting 1 . The e f f e c t of the mother. Hamsters - a) duration of play - Play f i g h t i n g among hamster s i b l i n g s r a i s e d with the mother ceased at approxi-mately the same time regardless of the testing s i t u a t i o n . Table 1 shows that play f i g h t i n g stops at age I4J4. days i n the arena, and J4.6 days i n the home cage and i n the arena when pups from both cages are mixed. However, play f i g h t i n g with the mother ceases when the young are 3J4. days old, which i s approximately the time when the mother would once again resume her estrus cycle (Dieterlen, 1 9 5 9 ) . b) i n t e n s i t y of play - An analysis of variance showed that there was no s i g n i f i c a n t difference between the average number of play f i g h t s per 1 5 minute period during the age period when play f i g h t i n g occurred (Table 2c) i n the d i f f e r e n t situations. Thus i t would appear that i n t e n s i t y of playing does not depend upon the s i t u a t i o n i n which i t i s tested. c) onset of f i g h t i n g - The onset of f i g h t i n g between mother and young occurred at 33 days of age, one day p r i o r to the observed cessation of play f i g h t i n g between mother and young (Figure 3, Table l c ) . Real f i g h t i n g involving the mother was somewhat sporadic from i t s onset u n t i l 5 5 days, when i t became more frequent (Figure 3 ) . Shortly af t e r the mother and pups were separated at 6 l days, a l l the mothers ob-served f i g h t i n g with the young from 5 5 days onward gave b i r t h to l i t t e r s . As gestation i s 1 6 days, the mothers were pregnant at 1 7 the time of increased aggression. Fighting between s i b l i n g s began at age 1+0 days i n the arena, both when s i b l i n g s were together and when strangers from another cage were mixed i n . Fighting i n the home cage was de-layed u n t i l lj.9 days, although f i g h t i n g i n the cage began ear-l i e r with the mother (Table I c ) . When one set of young was ij.6 days old, i t was noted that the mother slept i n the o r i g i n a l nest while a l l four young slept i n another, sparser nest i n a d i f f e r e n t corner of the cage. When the young approached within approximately three inches of the mother's nest, the mother would dart at the young and chase them away. The older female continued t h i s defense of the nest u n t i l the end of the experiment at 55 days. She gave b i r t h to a l i t t e r ten days l a t e r . As the gestation period f o r these animals i s l 6 days, she was not pregnant at the onset of the observed nest defense. d) i n t e n s i t y of f i g h t i n g - There was no s i g n i f i c a n t difference between the average number of f i g h t s from the onset of f i g h t i n g u n t i l the end of the experiment under the d i f f e r e n t testing situations (Table 2d). Real f i g h t i n g does not seem to depend upon the test s i t u a t i o n f o r i t s i n t e n s i t y . Gerbils - a) duration of play - Play f i g h t i n g between g e r b i l s raised with the mother does not cease i n the home cage (Table l b , Figure i^a and lid) either between young or mother and young. In both cases, a drop i n play occurs at 1|5 days, but play resumes i n an unchanged form shortly thereafter. 18 In the arena s i t u a t i o n , t h i s drop i s permanent (Figure lj.b). When strange g e r b i l s are mixed i n the arena, play i s l a s t seen at ij.5 days. The drop i n play corresponds to the observation of E i b l - E i b e s f e l d t (1951) that play ceases at 1^ 5 days of age. Young ge r b i l s f i r s t showed sexual behaviour at Ij.5 days i n the present study. This behaviour consisted of grooming and s n i f -f i n g at the genitals, followed by attempted mounting of the fe-male by the male. b) i n t e n s i t y of play - There was no s i g n i f i c a n t difference between the average number of play f i g h t s under the three testing situations (Table 3c). Thus the te s t i n g s i t u a t i o n does not appear to affe c t the i n t e n s i t y of play. c) onset of f i g h t i n g - Real f i g h t i n g was not observed between g e r b i l s i b l i n g s i n any s i t u a t i o n or between the mother and young. Real f i g h t s between g e r b i l s of di f f e r e n t l i t t e r s began i n the arena at age 51 days. Real f i g h t s did not begin u n t i l after the age of cessation of play between strange g e r b i l s . d) i n t e n s i t y of f i g h t i n g - It was found that there was a s i g n i f i c a n t difference between the average num-ber of r e a l f i g h t s that occurred between strangers i n the arena and the average f o r s i b l i n g s both i n the home cage and arena (Table 3d). Thus, young g e r b i l s f i g h t s i g n i f i c a n t l y more with strangers than they do with f a m i l i a r animals. 2. Absence of the mother. Hamsters - a) duration of play - Among hamsters 19 kept communally without the mother, play f i g h t i n g ceased at approximately the same time between sibs and between strangers, regardless of the type of tes t i n g s i t u a t i o n . Table l a shows that play f i g h t i n g stopped at \\$ days i n the arena, both when the young were mixed and when only s i b l i n g s were present. Ces-sation occurred at li3 days i n the home cage. Table l a shows that there i s very l i t t l e difference between groups raised com-munally with or without the mother i n the time of cessation of play. Thus presence or absence of the mother has no apparent ef f e c t on the age of cessation of play f i g h t i n g between young hamsters. b) i n t e n s i t y of play - An analysis of variance (Table 2c) showed no s i g n i f i c a n t difference i n the av-erage number of play interactions per lj? minute period between a l l three t e s t s i t u a t i o n s . The same analysis showed no d i f f e r -ence between the average number of plays i n any test s i t u a t i o n f o r both hamsters raised communally with or without the mother. Thus presence or absence of the mother does not appear to a f f e c t the amount of play engaged i n by young hamsters. c) onset of f i g h t i n g - Among strangers i n the arena, f i g h t i n g began at 38 days. Between s i b l i n g s In both the arena and home cage, f i g h t s began at i i2 days of age (Table l c ) . Prom th i s data, i t would appear that the type of test i n g s i t u a t i o n has l i t t l e e f f e c t on the onset of f i g h t i n g . I t seems that absence of the mother does not change the time of onset of f i g h t i n g between young hamsters raised communally 20 (Table l c ) , but p o s s i b l y the presence of the mother may i n h i b i t somewhat the onset of aggression between the young i n the home cage. d) i n t e n s i t y of f i g h t i n g - There was no s i g n i f i c a n t difference among a l l test situations f o r the com-munally reared hamsters with or without the mother's presence (Table 2d) i n the average amount of r e a l f i g h t i n g per 15 minute test period. Thus, whether or not the mother i s present during the post-weaning period appears not to a f f e c t the amount of ag-gression among communally reared hamsters. Gerbils - a) duration of play - Gerbils of the communally raised group of s i b l i n g s showed no play behaviour (Table l b ) . b) Intensity of play - The lack of play shown by t h i s group i n a l l situations was not s i g n i f i c a n t l y d i f -ferent from the small amount of play shown i n a l l situations by g e r b i l s reared with t h e i r mothers. Thus presence or absence of the mother does not appear to a f f e c t the i n t e n s i t y of play f i g h t -ing among communally raised g e r b i l s . c) onset of f i g h t i n g - Gerbils raised communally without the mother showed no f i g h t i n g behaviour i n any s i t u a t i o n (Table Id). d) i n t e n s i t y of f i g h t i n g - The lack of r e a l f i g h t i n g between animals raised together without the mother was s i g n i f i c a n t l y lower at the .05 l e v e l of p r o b a b i l i t y from the amount shown between strangers who had been communally raised 21 (Table 3 d ) , although i t was not s i g n i f i c a n t l y d i f f e r e n t from any other communal s i t u a t i o n (Table 3 d ) . Thus the presence of the mother past the age of weaning serves to increase the ag-gressiveness of the young toward strangers. 3 . The e f f e c t of toys. Hamsters - a) duration of play - None of the ham-sters who were raised i n i s o l a t i o n with a b a l l was observed playing with the b a l l i n the home cage. This d i f f e r s from the observations of Wort (I96I4.) wherein a l l animals were observed manipulating the b a l l . Play f i g h t s ceased at age 35 days (Table l a ) . This i s much e a r l i e r than the time of cessation of play between com-munally reared hamsters. Thus i t would appear that communal rearing prolongs the cessation of play. b) i n t e n s i t y of play - Analysis of variance shows the average number of play f i g h t s between the i s o l a t e s with toys to be s i g n i f i c a n t l y higher than the averages f o r the communally reared hamsters mixed with strangers i n the arena (Table 2a). This p a r t i c u l a r comparison was chosen i n order to make the test s i t u a t i o n of the communally reared groups be as s i m i l a r as possible as the s i t u a t i o n i n the arena faced by the i s o l a t e s . Each time an i s o l a t e i s placed i n the arena, he i s faced by strangers. By choosing to compare this with the 'mixed' communal groups wherein a communally raised hamster meets two t o t a l strangers and only one f a m i l i a r animal, the situations were kept f a i r l y comparable. 22 c) onset of f i g h t i n g - Real f i g h t s be-tween i s o l a t e s began at 29 days (Table l c ) . This i s much ear-l i e r than the age of onset of f i g h t s between communally raised hamsters. Thus, communal rearing delays the onset of f i g h t i n g between young hamsters. d) i n t e n s i t y of f i g h t i n g - Analysis of variance shows the average number of r e a l f i g h t s per 15 min-ute period to be s i g n i f i c a n t l y higher than the averages f o r both types of communally reared groups (Table 2 b ) . Thus, i s o l a t i o n s i g n i f i c a n t l y increases the i n t e n s i t y of both play and r e a l f i g h t i n g shown by the is o l a t e s over the l e v e l s shown by commun-a l l y reared hamsters. Gerbils - a) cessation of play - A l l the g e r b i l s reared i n i s o l a t i o n with a toy were observed engaged In play with the b a l l . B a l l manipulation occurred from the age of 27 days u n t i l the end of the experiment. Social play with the b a l l took the form of wrestling with the b a l l under the b e l l y , or pushing and kicking the b a l l around the cage with either fore or hind paws. Play f i g h t s between ge r b i l s who had been reared with a toy were not observed to cease (Table l b , Figure 5 a ) . However, a 'dip' i s indicated that i s somewhat si m i l a r to that shown by animals reared communally with t h e i r mothers (Figure l i ) . This took the form of a drop to one play i n t e r a c t i o n at 1+2 days. This i s preceded and followed by observations of a large number of play f i g h t s on days 39 and J4.5 (Figure 5 a ) . A second dip 23 around 5I4. days i s also indicated i n Figure 5a, but f i g h t i n g be-haviour occurs here and i s followed by play at a l a t e r age of 60 days. b) i n t e n s i t y of play - Table 3a shows that the average number of play interactions per 15 minute period f o r g e r b i l s raised with a toy i s s i g n i f i c a n t l y higher than f o r any other group. Thus, rearing with a toy i n i s o l a t i o n increases the amount of play between young g e r b i l s . c) onset of f i g h t i n g - Fighting begins at 5I4. days of age, but i s followed by some play. Thus the onset of f i g h t i n g behaviour does not exclude further play i n animals of t h i s group. d) i n t e n s i t y of f i g h t i n g - The average number of f i g h t s per 15 minute period i s not s i g n i f i c a n t l y d i f -ferent from the amount shown by Kaspar Hausers and s i b l i n g s raised communally without the mother (Table 3^)« Thus only the presence of the mother a f t e r weaning affects the i n t e n s i t y of f i g h t s between strangers i n the arena. I I . The e f f e c t of t o t a l i s o l a t i o n . Hamsters - a) cessation of play - Play f i g h t s among Kaspar Hauser hamsters ceased at 36 days, the time of ces-sation being very si m i l a r to that of hamsters raised with toys (Table l a ) . I s o l a t i o n from others r i g h t a f t e r weaning causes play f i g h t i n g to cease e a r l i e r than among communally raised ham-sters. b) i n t e n s i t y of play - an analysis of 2k variance shows that the average number of play f i g h t s per 15 minute period among Kaspar Hausers i s not s i g n i f i c a n t l y d i f f e r -ent from that of i s o l a t e s with toys, although the averages of the two i s o l a t e groups are s i g n i f i c a n t l y greater than those of both types of communally raised groups. Thus the two communal groups d i f f e r s i g n i f i c a n t l y from the two i s o l a t e groups i n the average number of play f i g h t s per 15 minutes, the communal groups playing l e s s . c) onset of f i g h t i n g - The onset of r e a l f i g h t i n g occurred at 28 days among Kaspar Hausers. This was very close to the age of onset of f i g h t i n g i n i s o l a t e s with toys (Table l c ) . Thus f i g h t i n g begins e a r l i e r i n i s o l a t e s than i n communally raised hamsters. d) i n t e n s i t y of f i g h t i n g - The average frequency of f i g h t s per 15 minutes i s not s i g n i f i c a n t l y d i f f e r -ent from that of i s o l a t e s with toys, but again the averages of both i s o l a t e groups are- s i g n i f i c a n t l y greater than those of both communal groups (Table 2b). Therefore, i s o l a t i o n leads to an i n -creased amount of aggression toward strange hamsters. Gerbils - a) cessation of play - Figure 5b shows the d i s t r i b u t i o n of play f i g h t s between Kaspar Hauser g e r b i l s . Play f i g h t s appear to cease after 30 days of age, but resume at ii8 days of age. However, they do not reappear afte r t h i s (Table l b ) . Again, there i s a 'dip' at 1±5 days, f o r at that age, no interactions occur. This i s not very clear, because of a lack of data f o r days 33, 1+2, and 51 • 25 b) i n t e n s i t y of play - The average amount of play shown i s not s i g n i f i c a n t l y d i f f e r e n t from the averages of both communally reared groups, although the average f o r i s o l a t e s with toys i s s i g n i f i c a n t l y higher (Table 3 a ) . Thus, the presence of a toy with an i s o l a t e d animal leads to an i n -creased amount of play with strangers. c) onset of f i g h t i n g - No r e a l f i g h t s were observed between Kaspar Hauser ge r b i l s (Table Id, Figure 5b). d) i n t e n s i t y of f i g h t i n g - The lack of f i g h t s i n t h i s group does not d i f f e r s i g n i f i c a n t l y from the averages of i s o l a t e s with toys or the s i b l i n g s reared communally without the mother (Table 3 b ) , but the amount shown by communals reared with the mother i s s i g n i f i c a n t l y higher than a l l other groups. Thus i n g e r b i l s , i s o l a t e s raised with toys show s i g n i -f i c a n t l y more play that the other groups which do not d i f f e r among themselves. When young g e r b i l s which have been reared communally with the mother are put i n a neutral arena with a stranger, they show s i g n i f i c a n t l y more f i g h t i n g than a l l other groups, which do not d i f f e r among themselves. B. C r i t e r i a f o r D i f f e r e n t i a t i n g Play and Real Fights 1. Lengths of i n d i v i d u a l interactions. Hamsters - Wort (196J4.) showed that there was a d e f i n i t e difference between the d i s t r i b u t i o n s of play and r e a l f i g h t durations i n weaned hamsters. I t was also shown that there 26 were no marked peaks i n the d i s t r i b u t i o n of play durations i n pups p r i o r to weaning. As the sample f o r determination of t h i s was small, t h i s i n v e s t i g a t i o n was repeated using a larger sam-ple size of li|-3 interactions compared to i\l i n the previous study. The results (Figure 6) support the previous conclusion that there are no d e f i n i t e peaks i n the d i s t r i b u t i o n of these durations i n infant animals, although very few occur that are longer than 35 seconds duration. Gerbils - To determine the d i s t r i b u t i o n s of pre-and post-weaning play and of r e a l f i g h t s i n g e r b i l s , s i m i l a r graphs were made p l o t t i n g t o t a l numbers of interactions against duration i n seconds (Figure j). Real f i g h t s were d i s t r i b u t e d such that there was a peak at one second f o r both juveniles and adults of the breed-ing stock (Figure 7a,b) although sample sizes were small. Like-wise, play f i g h t s i n animals p r i o r to weaning showed a peak at one second (Figure 7 c ) . Juvenile g e r b i l s showed a large peak at between one and two seconds (Figure 7 d ) . Thus there Is very l i t t l e difference i n d i s t r i b u t i o n of the lengths of play and r e a l f i g h t s at any age. 2. Latencies to i n t e r a c t . A number of workers (Seward, 19^5; King, 195&, 1957) have used the length of latency from introduction to time of the f i r s t f i g h t as a measure of aggressiveness i n rodents. In order to determine i f latency was a good measure of aggres-siveness i n hamsters and g e r b i l s , latencies to i n t e r a c t were 27 measured to the nearest 0 .2 second. Figure 8a i s a graph showing the average number of play interactions following a p a r t i c u l a r latency. Here, latencies are rounded to the nearest minute. Figure 8b shows the average number of r e a l f i g h t s following par-t i c u l a r l atencies. Figure 8a shows that there i s a general ten-dency f o r fewer play f i g h t s to follow a long latency. However, this i s very general, and i s to be expected because the longer the latency, the less time i s l e f t i n which interactions can occur. Figure 8b shows even less c o r r e l a t i o n between latency and number of f i g h t s . Figure 8c shows the average number of play interactions following latencies i n g e r b i l s , while Figure 8d shows the average number of r e a l f i g h t s following a p a r t i c u l a r latency. In neither case i s there a d i s t i n c t c o r r e l a t i o n between latency and the num-ber of following interactions. 3* Number of animals involved i n play. Although Dieterlen (1959) states that only two ham-ster pups are involved i n any one play interaction, i t became ap-parent i n the course of thi s study that f a i r l y often three animals were involved simultaneously i n one play f i g h t . Data were taken to ascertain the frequency of t h i s type of occurrence. Of 568 play f i g h t s i n weaned animals, I4.O were observed i n which three animals were involved. This i s 7 .0$ of the int e r a c t i o n s . Of 139 play f i g h t s i n infant animals, 19 or 13.7$ involved three animals. Nine hundred thirty-seven r e a l f i g h t s were observed. None of these involved more than two animals. 28 As only two animals constituted an experimental sub-group of g e r b i l s , i t was impossible to ascertain i f more than two would have been involved i n play af t e r weaning. However, $6 play f i g h t s i n infant animals were observed. In a l l cases, three or more young were present i n the home cage. In no instance were more than two animals involved i n an i n t e r a c t i o n . ij.. Sounds uttered during interactions. Wort (196I1J showed that hamsters can and do u t t e r sounds during both play and r e a l f i g h t i n g . E i b l - E i b e s f e l d t (1951) states that although f i g h t i n g g e r b i l s squeak, play f i g h t i n g ones do not. To check t h i s , tape recordings were made during play f i g h t s of these animals. I t was found that none of the animals uttered sounds during this time. C. Choice of Partner f o r Interaction 1. Play f i g h t i n g . When hamsters reared communally with or without the mother were mixed (intragroup mixing) each hamster was then i n the presence of one sib and two strangers. During the course of ob-servations, i t was noted i f the hamsters engaged i n playing were playing with the member of h i s own l i t t e r or with a 'stranger'. It was noted that only 29$ of play f i g h t s involved mem-bers of the same l i t t e r . The remaining 71% involved members of d i f f e r e n t l i t t e r s . 2. Real f i g h t i n g . During intragroup mixing of communally reared ham-sters, i t was found that only 10$ of r e a l f i g h t s involve members 29 of the same l i t t e r , ^0% involve members of d i f f e r e n t l i t t e r s . D. L i t t e r Sizes During the course of t h i s study the average l i t t e r size f o r hamsters was 5*4 while i n Wort's study (196J4.) average l i t t e r size was 9«0- The average g e r b i l l i t t e r size during t h i s study was 3.7. DISCUSSION 30 Play i s a c h a r a c t e r i s t i c phenomenon of mammals, espe-c i a l l y of young ones. Play may be divided into s o c i a l and s o l i -tary a c t i v i t i e s . S o c i a l play usually involves a companion, and so c i a l r e s t r a i n t s are maintained during the bout. Meyer-Hoizapfel (1956) describes the t r a n s i t i o n from play to r e a l a c t i v i t i e s by the assumption that the play a c t i v i t y can produce an urge toward r e a l behaviour and, with the i n t e n s i f i c a t i o n of excitement, pro-duces a drive toward the r e a l a c t i v i t y . Play occurs with respect to an object which does not always have to take part i n the action. According to Meyer-Holzapfel (1956), a companion of the same species i s the optimum play partner, probably because i t plays back. She states that the more an object approaches t h i s c h a r a c t e r i s t i c , not having to be continually moved but a c t u a l l y or apparently carrying out i t s own movement, the more r e a d i l y w i l l i t be accepted as a playmate. Mobility might be the most important c h a r a c t e r i s t i c of a play ob-ject, she postulates. Wort (1961L) found that t h i s possibly i s correct, f o r hamsters played with a b a l l less than they played with one another. However, i n the present study, young hamsters were not observed to play with a b a l l , and a l l young gerbils that had a b a l l i n the cage were observed to play with i t . Some young ge r b i l s were not observed to play with one another at a l l . As another g e r b i l i s supposedly more mobile than a b a l l , the mobil-i t y of a play object seems to matter less to ger b i l s than i t does to hamsters. Hamsters, when they play with a b a l l , play less than 31 they would with another hamster. Thus Meyer-Holzapfel «s postu-l a t i o n concerning the importance of mobility of a play object to animals i n general should be amended as there are exceptions to her r u l e . One p a r t i c u l a r type of play behaviour i s "mock" or "play' 1 f i g h t i n g which d i f f e r s from r e a l f i g h t i n g In various ways (Ei b l - E i b e s f e l d t , 1951; Dieterlen, 1959; Rowell, 196I; Wort, 1 9 % ) . Real f i g h t i n g has been studied i n rats and mice by many workers (Ginsburg and Al l e e , 19k2; H a l l and Kl e i n , 19^2; Seward, 19^5; Kahn, 1951].; King and Gurney, ±%k', King, 195&; 1957; Levine, 1959; Denenberg, Hudgens, and Zarrow, 19614.), and the t r a n s i t i o n between play and r e a l f i g h t i n g has been observed i n the golden hamster (Meyer-Holzapfel, 1 9 5 ° ; Dieterlen, 1959; Rowell, I 9 6 I ; Wort, I96I4.) and the Persian g e r b i l ( E i b l - E i b e s f e l d t , 1951). Meyer-Holzapfel (195&) states that i n f i g h t i n g games, a companion merely assumes the role of the enemy, and c e r t a i n "emotional" conditions characterizing serious intent are lacking. Because i t i s impossible to state how the animal i t s e l f perceives the si t u a t i o n , i t i s e n t i r e l y useless to describe the differences between r e a l and mock behaviour i n such subjective terms. The outside observer cannot measure the "emotions" of the p a r t i c i -pants, but may state only observable differences i n the behaviour of the animals during such interactions and can measure these d i f -ferences i n behaviour quantitatively. It i s misleading to d i f f e r -entiate play and r e a l f i g h t s on the basis of indescribable and i m -measurable emotions. 32 That s o c i a l r e s t r a i n t s are maintained during play-f i g h t i n g can be shown by the checking of b i t i n g which occurs dur-ing such games. Serious b i t i n g i s supposedly restrained due to role reversal by the p a r t i c i p a n t s . In r e a l f i g h t i n g , role rever-s a l does not occur. Meyer-Holzapfel (195&) states that sham f i g h t s can become genuine when too much of a s p e c i f i c urge to f i g h t i s mixed i n . Once more, she attempts to describe aspects of behaviour i n subjective terms which again makes the hypothesis untestable. Scott and Fredericson (1951) believe that the cause of most f i g h t i n g i s pain from b i t e s and scratches, rather than a " s p e c i f i c urge to f i g h t " . Their hypothesis seems more reasonable, f o r many observed f i g h t s began by one animal b i t i n g another. In the very few interactions observed wherein a play f i g h t changed into a r e a l f i g h t , a b i t e occurred immediately before the change-over. One of the statements made by Dieterlen (1959) has been shown to be incorrect, i n that more than two hamsters may be i n -volved simultaneously i n a play f i g h t . Almost li}. percent of play Interactions p r i o r to weaning involve three animals, although this percentage i s halved af t e r weaning. Wort (196ii) found that the duration of an i n t e r a c t i o n i s a basic difference between play and r e a l f i g h t s i n hamsters. This does not hold f o r the Mongolian g e r b i l . Both r e a l and play f i g h t s f o r a l l ages of gerbil s are d i s t r i b u t e d with a peak at ap-proximately one second. Wort (196ii) also found that play f i g h t s i n infant 33 hamsters assumed a s t r a i g h t - l i n e d i s t r i b u t i o n . The present study repeated t h i s i n v e s t i g a t i o n using a much larger sample si z e . The results corroborated the previous f i n d i n g . Rowell (1961) thinks that i n the wild the mother ham-ster would normally leave the young when they were weaned, but Dieterlen (1959) believes t h i s would not occur u n t i l the pups were about 35 days old, when they begin to show t e r r i t o r i a l i t y . Wort (19614.) gave support to Dieterlen's ideas, f o r during the time of increased aggressiveness of the mother, the mother showed no tendency to nest i n another corner as she probably would have had Rowell's idea of the mother's departure been correct. In the present study, the mother hamster began f i g h t i n g with the young when they were 33 days old. Much chasing was seen at this time. When the pups were I4.5 days old, they were observed to nest i n a di f f e r e n t corner from the female. When they approached her nest, the nonpregnant female would chase the young away. These r e s u l t s indicate that probably Dieterlen and Wort are correct i n assuming that the young would be driven o f f by the female's increasing ag-gressiveness . A l l of the ge r b i l s reared with toys were observed par-t i c i p a t i n g i n s o c i a l play with a table tennis b a l l . These animals not only wrestled with the b a l l i n the same manner that other ex-perimental g e r b i l s wrestled with one another when engaged i n play f i g h t i n g , but also pushed i t round and round the cage. It would appear that the Mongolian g e r b i l has the a b i l i t y to use an i n a n i -mate object as a play substitute when companions of i t s own 3k species are not present. Wort (I96J4.) found that hamsters would play with the b a l l also. However, none of the hamsters i n the present study were observed playing with the b a l l . This i s pos-s i b l y due to the differences i n average l i t t e r size between the two studies. The average l i t t e r size i n the present study was f i v e , compared to nine i n Wort's investigation. S e i t z (1954) has shown that l i t t e r size greatly affects s o c i a l behaviour i n adult ra t s . Rats from large l i t t e r s exhibited much more s o c i a l and sexual behaviour than rats from small l i t t e r s . They were also more successful i n competition f o r food than those from small l i t t e r s . I t i s reasonable, then, that hamsters from small l i t -ters would exhibit less s o c i a l behaviour than those from large l i t t e r s . In t h i s p a r t i c u l a r case, s o c i a l behaviour was s o c i a l play with a b a l l . It i s possible, also, that a hamster pup needs a c e r t a i n amount of experience i n playing before i t w i l l use an inanimate object as a s o c i a l substitute. I f this experience i s not provided i n a small l i t t e r , the weaned pup w i l l not play with the b a l l . I f the hamster does not play s o c i a l l y with the b a l l , there i s then no difference i n s o c i a l experience a f t e r weaning between i s o l a t e s with or without a b a l l . The r e s u l t s bear t h i s out, f o r there i s a difference of only one day i n the age of ces-sation of play f i g h t i n g and age of onset of r e a l f i g h t i n g i n these groups, and there i s no s i g n i f i c a n t difference i n the amounts of play and r e a l f i g h t i n g per f i f t e e n minute period shown by the two groups. Among hamsters reared communally with the mother, 35 f i g h t i n g with the mother began at age 33 days, but f i g h t s between si b l i n g s i n the home cage did not s t a r t u n t i l the fort y - f o u r t h day. Fights between young reared communally without the mother did not begin i n the home cage u n t i l the forty-second day. The two groups were very s i m i l a r i n the time of onset of r e a l f i g h t -ing i n the arena and i n mixed groups, as they were i n time of ces-sation of play i n a l l three test s i t u a t i o n s . There was also no s i g n i f i c a n t difference i n the average number of interactions per f i f t e e n minutes among any of the test situations of the two com-munally reared groups. Thus the only r e a l difference between com-munally reared hamsters i s that young hamsters raised with the mother a c t u a l l y f i g h t e a r l i e r than do those raised with s i b l i n g s only because they engage i n f i g h t s with the mother at an early age. The young hamsters of both i s o l a t e groups began f i g h t i n g at 2 9 and 2 8 days. Cessation of play occurred at 35 and 36 days. There was no s i g n i f i c a n t difference between these two groups i n the number of interactions per f i f t e e n minutes, although t h e i r numbers were s i g n i f i c a n t l y greater than the numbers shown by both types of communal groups. It would appear that s o c i a l controls were not well developed i n these animals due to t h e i r lack of s o c i a l experience. The Isolated animals appeared to be more sensitive to s o c i a l situations than those reared communally. Denenberg et a l (196i|) found that mice reared i n i s o l a t i o n were more active than those reared communally, while Ginsburg and Allee (19U-2) and Kahn (1951+) found that f i g h t i n g tendencies i n communally reared mice 36 are less than i f they were reared from weaning on i n i s o l a t i o n . This i s true also f o r the golden hamster. As well as beginning to f i g h t e a r l i e r , those raised i n i s o l a t i o n had a higher frequency of f i g h t i n g and playing than those reared together. The i s o l a t e d animals appeared much more sensitive to the presence of other ani-mals than did those 'used' to i n t e r a c t i n g with other animals. Beach (19I4.2) says that segregated animals show "greater excita-b i l i t y r e s u l t i n g from the novelty of contact with a second ani-mal". Wort (196)4.) found that hamsters raised i n i s o l a t i o n with a toy showed much higher aggression than those of any other group. That was not so i n the present study, f o r the pups did not play with the b a l l s . Wort (196I4.) explained the increased aggression of those reared with toys i n that the animals were unused to nega-tive input from other animals but were used to being able to con-t r o l the movements of other objects. Their i n a b i l i t y to i n h i b i t agression through s o c i a l controls, t h e i r h y p e r s e n s i t i v i t y to s o c i a l contacts, and t h e i r f a m i l i a r i t y with a s i t u a t i o n i n which they alone manipulated movable objects within t h e i r reach would lead to an increase i n aggression. However, I f the hamsters did not play with the b a l l , the l a s t f a c t o r of f a m i l i a r i t y of mani-pulation would not come into play, and the 'toy' pups should re-act l i k e Kaspar Hausers. This has been shown to be true. The communal groups had been receiving constant stimulus input i n the form of other animals, while the i s o l a t e groups had no stimulus input i n the form of other animals since weaning. Thus, they had 37 no opportunity to learn any s o c i a l controls which serve to i n -h i b i t f i g h t i n g and were unused to the presence of moving objects. Thus, they were more sensitive to the movements of the other ani-mals and were less able to i n h i b i t t h e i r own reactions i n the form of aggression to these other animals. Gerbils reared communally with the mother and Kaspar Hausers show a ce r t a i n small amount of play after weaning, and although g e r b i l s reared communally without the mother were not seen to play, the three groups do not d i f f e r s i g n i f i c a n t l y i n the average amount of play shown per 15 minute period In any test s i t u a t i o n . However, those with toys show s i g n i f i c a n t l y more play than do the pups of any other group. I s o l a t i o n without the pres-ence of a b a l l appears to have l i t t l e e f f e c t on the amount of play shown, but i s o l a t i o n i n the presence of a b a l l appears to increase the amount of play engaged i n when two such animals meet. These p a r t i c u l a r animals were seen to indulge i n much play with the b a l l . The b a l l would not r e s i s t any play movements and would i n f l i c t no pain on the pup, and might serve to reduce the amount of play shown by communally-reared pups, which would have met resistance and perhaps some pain. The Kaspar Hauser gerbil s showed no more play than did those reared communally. They would be unused to moving objects and would less r e a d i l y ap-proach something moving. Indications of this can be seen i n some of the behaviour exhibited by these animals. Very often, two pups would approach one another h e s i t a t i n g l y and might even touch, but they would then spring apart and dash a short distance apart. 38 The approach would then be repeated, but would r a r e l y go beyond tentative touching and s n i f f i n g . On the other hand, communally-reared g e r b i l s paid very l i t t l e attention to one another. With the exception of g e r b i l s communally raised with the mother mixed i n the arena so that they met only strangers, a l l g e r b i l s showed l i t t l e or no aggression. However, communals with the mother mixed showed s i g n i f i c a n t l y more figh t s per 15 minute period than any other group. This i s quite sensible i f one considers the s o c i a l l i v e s of the animals. The s i t u a t i o n wherein young are reared with the mother after weaning i s clos-est to the wild situation, f o r the animals l i v e i n groups and have a well developed system of communication. The young read-i l y remain with the parents, but as E i b l - E i b e s f e l d t (1951) states, a stranger may be attacked and driven o f f . The 'communal with mother-! ge r b i l s should show l i t t l e or no f i g h t i n g when with f a m i l i a r animals i n the home cage or arena, f o r t h i s would be disrupting to the l i f e of the colony. However, i t i s not sur-p r i s i n g that aggression i s shown toward strangers i n the arena, f o r t h i s s i t u a t i o n would be analogous to that of r e p e l l i n g an intruder from the colony. Both types of i s o l a t e s would be expected to f i g h t very l i t t l e f o r the animals are not established colony members and would be expected to attempt f r i e n d l y s o c i a l contacts with an-other animal or group. It i s true that these animals f i g h t very l i t t l e and continue play behaviour past the onset of sexual be-haviour. Animals reared with the mother play past t h i s point 39 only with f a m i l i a r animals. After i|5 days of age, which E i b l -E i b e s f e l d t (1951) noted as the time of cessation of play and which appears to be the onset of sexual a c t i v i t y , animals reared with the mother f i g h t with strangers. Animals reared communally without the mother do not f i g h t at a l l , perhaps because the pres-ence of a parent or older animal promotes colony establishment, or perhaps the presence of more than two animals promotes colony establishment. The l a t t e r i s possible, because i n the course of the experiment, a set of two pairs kept communally bred more ra p i d l y than did pairs kept alone. There appears to be a dip or change i n behaviour at. approximately l\$ days of age. E i b l - E i b e s f e l d t (1951) noted that play disappeared from Persian gerbi l s at this time. Some g e r b i l s i n t h i s study showed awakening sexual behaviour at t h i s age. However, the type of behaviour appearing a f t e r this point appears to depend on the s o c i a l environment i n which the animals are l i v -ing. Animals i n established colonies (reared with the mother) show aggression toward strangers only, while animals from a non-c o l o n i a l s i t u a t i o n ( a l l other groups) generally show contact-promoting play behaviour. SUMMARY AND CONCLUSIONS In an attempt to discover some of the effects of post-weaning s o c i a l experience on play and agonistic behaviour, 25-day old golden hamsters and Mongolian g e r b i l s were divided into four groups which d i f f e r e d with respect to s o c i a l environment. Prom 4 the ages of 26 to 6 l days, these animals were tested f o r the num-ber of play and f i g h t interactions i n a 15-minute i n t e r v a l . I t was found that play and r e a l f i g h t s between g e r b i l s do not d i f f e r i n duration, both averaging one second i n length. It was noted that the latency before i n t e r a c t i o n i s not a h e l p f u l tool to measure aggression i n either hamsters or g e r b i l s . Before weaning, lit percent of play interactions i n ham-sters involve more than two animals, while a f t e r weaning the per-centage i s halved. Gerbils do not u t t e r sounds while engaged i n play f i g h t i n g . Communally reared hamsters play f i g h t with strangers 71 percent of the time, while 90 percent of r e a l f i g h t s involve strangers. Communally raised hamsters cease playing at J4.3 to J4.6 days of age, and begin f i g h t i n g at 38 to J4.2 days of age, unless f i g h t i n g i s observed i n the home cage i n the presence of the mother. If this i s the case, the young begin f i g h t i n g with the mother at approximately 33 days, while f i g h t i n g among the young i s delayed u n t i l approximately 49 days. Isolated hamsters cease playing at 35 to 36 days of age, and begin f i g h t i n g at 28 to 29 days of age. Thus i s o l a t i o n leads to an early cessation of play and an ea r l y onset of f i g h t i n g . Isolated animals also play and f i g h t s i g n i f i c a n t l y more than do communally raised hamsters, as they are more sensitive to s o c i a l situations. Young hamsters raised with a ping pong b a l l as a toy were not observed playing with the b a l l and did not d i f f e r s i g n i f i c a n t l y from Kaspar Hausers i n any aspect of play or r e a l f i g h t i n g . Gerbils raised communally with the mother f i g h t with strangers s i g n i f i c a n t l y more than they do with f a m i l i a r animals. In t h i s one type of test s i t u a t i o n , they also f i g h t s i g n i f i c a n t l y more than do g e r b i l s reared under a l l other types of s o c i a l en-vironment. This can be explained as an attempt to drive out strangers from an established colony, while s o c i a l interactions between animals from other types of s o c i a l environment are con-tact rpromoting, or an attempt to e s t a b l i s h or j o i n a colony. Gerbils reared i n i s o l a t i o n with a toy showed s i g n i f i -cantly more play than did animals from any other group. They were used to an object that moved but i n f l i c t e d no pain, so were not i n h i b i t e d about engaging i n play with another moving object, i n t h i s case another gerbil." There i s a l u l l or dip i n play behaviour of ge r b i l s at about Ij.5 days of age. The behaviour appearing afte r this point de-pends upon the type of s o c i a l environment the animal Is l i v i n g i n . Thus, s o c i a l experience a f t e r weaning affects the amount and time of cessation of play and the onset and amount of r e a l f i g h t s among s i b l i n g golden hamsters. The same types of s o c i a l experience a f t e r weaning af f e c t the amount of both play and r e a l f i g h t i n g between young Mongolian g e r b i l s . k2 LITERATURE CITED Alle e , W. C , 1 9 5 8• The Social L i f e of Animals. Beacon Press, Boston. Beach, P. A., 19J4.2. Comparison of copulatory behavior of male rats raised i n i s o l a t i o n , cohabitation, and segrega-tion.* J. Genet. Psychol. 60: 121 - 1 3 6 . Beach, P. A., and J. Jaynes, 1951+' E f f e c t s of early experience upon the behavior of animals. Psychol. B u l l . 5 1 : 2 3 9 - 2 6 3 . Bingham, W; E., and W. J. G r i f f i t h s , 1 9 5 2 . The e f f e c t of d i f f e r -ent environments during infancy on adult behavior i n the r a t . J. Comp. Physiol. Psychol, 3 0 7 - 3 1 2 . Bond, C. R., 19l|5« The golden hamster (Cricetus auratus) - care, breeding and growth. Physiol. Zool. 1 8 : 5 2 - 5 9 * Bruce, H. M., and E. Hindle, 193^4-« The golden hamster (Cricetus  [Me so cricetus] auratus Waterhouse ): care, breeding and growth. Proc. Zool. Soc. London. 2 : 3 6 1 - 3 6 6 . C o l l i a s , N., 19^J-' Aggressive behavior among vertebrate animals. Physiol. Zool. 1 7 : 8 3 - 1 2 3 . Denenberg, V. H., 1 9 6 2 . "The effects of early experience" i n The Behaviour of Domestic Animals, ed. by E. S. E. Hafez. B a l l i e r e , T i n d a l l , and Cox, London. Denenberg, V. H., Hudgens, G. A., and M. X. Zarrow, I96J4.. Mice reared with r a t s : modification of behavior by early experience with another species. Science llj - 3 : 3 8 O - 3 8 I . Dieterlen, P., 19^9• Das Verhalten des syrischen Goldhamsters. Z e i t . f u r . Tierpsychol. l 6 : I4.7-IO3. E i b l - E i b e s f e l d t , I., 1951* Gefangenschaftsbeobachtungen an der persischen Wustenmaus (Meriones persicus persicus Blanford): E i n Betrag zur vergleichenden Ethologie der Nager. Zei t . f u r Tierpsychol. 8 : I4.OO-J4.23. Eisenberg, J. P., 1 9 6 2 . Studies on the behavior of Peromyscus  maniculatus gambelii and Peromyscus c a l i f o r n i c u s  p a r a s i t i c u s . Beh. 1 9 : 1 7 7 - 2 0 7 . Ginsburg, B. G., and W. C. Allee, I9I4.2. Some effects of condi-tioning on s o c i a l dominance and subordination i n inbred strains of mice. Physiol. Zool. 1 5 : I4.85-506. 43 H a l l , C. S., and S. J. Klei n , 1942- Individual differences i n aggressiveness i n r a t s . J. Comp. Psychol. 33: 371-383-Kagan, J., and P. A. Beach, 1953- E f f e c t s of ear l y experience on mating behavior i n male r a t s . J. Comp. Psychol. 4 6 : 204-208. Kahn, M. V., 1954' I n f a n t i l e experience and the mature aggres-sive behavior of mice: some maternal influences. J. Genet. Psychol. 84: 65-75. King, J. A., 1956. Sexual behavior of C57BL/10 mice and i t s re-l a t i o n to early s o c i a l experience. J. Genet. Psychol. 88: 223-229. King, J . A., 1957. Relationships between early s o c i a l experience and adult aggressive behavior i n Inbred mice. J. Genet. Psychol. 90: 151-166. King, J . A., 1958. Parameters relevant to determining the e f f e c t of early experience upon the adult behavior of animals. Psychol. B u l l . 55: 4 6 - 5 8 . King, J. A., and B. E. Ele f t h e r i o u , 1959- E f f e c t s of early hand-l i n g upon adult behavior i n two subspecies of deermice, Peromyscus maniculatus. J. Comp. Physiol. Psychol. 52: 8 2 - 8 8 . King, J. A., and N. L. Gurney, 1954« E f f e c t of early s o c i a l ex-perience on adult aggressive behavior i n C57BL/10 mice. J. Comp. Physiol. Psychol. 4 7 : 326-330. Levine, S., 1959- Emotionality and aggressive behavior i n the mouse as a function of i n f a n t i l e experience. J. Genet. Psychol. 9I4.: 77-83. Littman, R. A., 1956. I n f a n t i l e experience and adult behavior i n the white r a t . J. Genet. Psychol. 88: 11-24-Luchins, A. S., and R. H. Porgus, 1955* The ef f e c t of d i f f e r e n -t i a l post-weaning environment on the r i g i d i t y of an animal's behavior. J. Genet. Psychol. 86: 51-58. Melzack, R., and W. R. Thompson, 1956. E f f e c t s of early exper-ience on s o c i a l behaviour. Canad. J . Psychol. 10: 82-90 . ~ Meyer-Holzapfel, M., 1956. S p i e l der Saugetiere. Hdbch. der Zobl. Vol. 8, Fas s i d e 2 . Rosen, J., and P. M. Hart, 1963. E f f e c t s of early s o c i a l i s o l a -l a t i o n upon adult t i m i d i t y and dominance i n Peromyscus. Psych. Reports 13: 47-50. 104-Rowell, T. E., i 9 6 0 . On r e t r i e v i n g of young and other behaviour i n l a c t a t i n g golden hamsters. Proc. Zool. Soc. London. 135: 265-282. Rowell, T. E., 1961. The family group i n golden hamsters: Its formation and break-up. Beh. 17: 81-9)+. Scott, J. P., and E. Fredericson, 1951' The causes of f i g h t i n g i n mice and rats . Physiol. Zool. 2it: 273-309. i Seitz, P., 1954' The effects of i n f a n t i l e experience upon adult behavior i n animal subjects: I Eff e c t s of l i t t e r size during infancy upon adult behavior i n the rat . Amer. J. Psychiat. 110: 916-927. Seitz, P. F. D., 1959« I n f a n t i l e experience and adult behavior In animal subjects. II Age of separation from the mother and adult behavior i n the cat. Psychosom. Med. 21: 353-378. Seward, J. P., 191+5. Aggressive behavior i n the r a t . 1. General c h a r a c t e r i s t i c s ; age and sex differences. J. Comp. Psychol. 38: 175-197. Simpson, G. G., 1945' The p r i n c i p l e s of c l a s s i f i c a t i o n and a c l a s s i f i c a t i o n of mammals. B u l l . Am. Mus. Nat. Hist. 85: 1-350. Wort, M. H., 196i|.. The effects of s o c i a l experience after wean-ing on the onset and amount of agonistic behaviour between s i b l i n g golden hamsters. Unpubl. B. Sc. thesis, University of B r i t i s h Columbia. Appendix 1. Analyses of variance f o r the determina-t i o n of between treatment and between test s i t u a t i o n s i g n i f i -cance f o r hamsters and g e r b i l s . I Between treatment play i n hamsters. II Between treatment f i g h t s i n hamsters. I l l Between test s i t u a t i o n play i n hamsters. IV Between test s i t u a t i o n f i g h t s i n hamsters. V Between treatment play i n g e r b i l s . VI Between treatment f i g h t s i n g e r b i l s . VII Between test s i t u a t i o n play i n g e r b i l s . VIII Between test s i t u a t i o n f i g h t s i n g e r b i l s . Appendix 1 Number I II I I I IV V VI VII VIII Analyses Source of Variance Treatment (between) Error (within) Total Treatment Error Tre atment Error Treatment Error Treatment Error Treatment Error Treatment Error Treatment Error Total Total Total Total Total Total Total of Variance S.S. f 372.14-5 3 1254.18 99 1626.63 1440.28 6057.83 7498.11 72.08 2238.84 2310.92 117.97 3578.95 3696.92 43.10 3 3 - 5 4 76.64 7.5 3-7 11.2 15.60 90.87 106.47 8.44 3*00 1 1 . 4 4 3 155 5 232 236 3 34 3 23 5 58 M.S. 124.15 12.67 480.09 4 8 . 3 7 14.41 9.96 23.59 15.17 14.37 0.99 2 .5 0.2 3-12 1.62 I . 6 9 0.05 P 9.8 tt* 9.9 1.4 N.S. 1.6 N.S. 14.5 * * 12.5 1.9 N.S. 33.8 * * "Square root transformation used to treat data. Table 1. Ages of cessation of play and onset of r e a l f i g h t i n g f o r hamsters and ge r b i l s raised under d i f f e r e n t s o c i a l conditions and tested under d i f f e r e n t situations. Table 1 Flay Fighting Condition Age of Cessation a) Hamsters A with strangers I p days A £u*©n8. i 11\ A home cage 5© ( 3 I 4 . with mother) B with strangers 4-5 B arena B home cage 4 3 C 3 5 D 3 0 b) Gerbils A with strangers 1 + 5 A . arena 3 9 A home cage n i l B with strangers B arena B home cage C n i l D 1+8 Real Fighting Condition Age of Onset c) Hamsters A with strangers A arena A home c age B with strangers B arena B home cage C D 1+0 days l+o 1 + 9 ( 3 3 with mother) ? 1 + 2 2 9 2 8 d) Gerbils A with strangers A arena A home c age B with strangers B arena B home cage C D 5 1 n i l n i l n i l n i l n i l $k n i l Table 2. Differences between groups and test situa< tions f o r play and r e a l f i g h t i n g i n hamsters. Table 2 Hamsters Type of Condition No. Total No. Avg. No. Signi-Inter- Repli- Inter- per 15 ficance action cates actions minutes a. Play A 1x2 91 2 .2 1 N S D B 1x0 1x2 1.1 J } o 10 69 6 .9 i U S D J D 11 59 5-4 J B arena 4O 46 1.2 B home cage 3 ° 79 2.2 b. Real A 4k 95 2 .2 N S D -\ Fighting B 40 71 l . g . ; 7 * C 33 290 8.8 1 N S D J D 34 227 6 .7 J c. Play A with strangers 1x2 91 2.2 j r . A arena 38 i+0 1.1 A home cage I(.2 92 2.2 s . B with strangers 4O 1x2 1.1 D , Real A with strangers Ixlx. 95 2 .2 N > Fighting A arena 4k 73 1.7 A home cage 2o 9 0 .3 3 . B with strangers 1x8 71 1*5 B arena 4O 12 0.3 D. B home cage 4O 7^ 1-9 Table 3. Differences between groups and test s i t u a -tions f o r play and r e a l f i g h t i n g i n g e r b i l s . Table 3 Gerbils Type of Condition No. Total No. Avg. No. Signi-Inter- Repli- Inter- per 15 ficance action cates actions minutes Play A 8 11.2]+ l . i | l 1 B 12 12.00 1.00 \ • NSD -D 6 8.1J.7 l . k l J \ V* C 12 4 1 . 8 4 3 ^ 9 j b. Real Fighting A B C D 4 12 1 6 o l 0 1.2 0.0 0 .3 0.0 -V NSD •K-Play A with strangers 8 11 l . i i JJ_ A arena 6 2 0 .3 A home cage 12 10 0.8 g_ B with strangers 12 0 0.0 B arena 12 0 0 .0 D > B home cage 12 0 0.0 Real A with strangers 4 6 1.2 Fighting A arena 12 0 0.0 ^ v •» A home cage 12 0 0 .0 B with strangers 12 0 0.0 -) NSD B arena 12 0 0 .0 B home cage 12 0 0 .0 Figure 1. Arrangement of hamsters i n the experimental s o c i a l conditions. Figure 1 Exper imenta1 Condition Subgroups Cages Subgroup Hamsters Cage 1 mother, 4 young A etc. (9) 4 young B etc. (9) etc. (9) D etc. (9) 1 young + b a l l -1 young Figure 2. s o c i a l conditions. Arrangement of gerbi l s i n the experimental Figure 2 Experimental Condition Subgroups Cages Subgroup Gerbils Cage D 1 mother, 2 young 2 young B 1 1 young -T- b a l l 1 young Figure 3. Play and r e a l f i g h t i n g between the mother and young hamsters. Figure li. Average number of interactions between ger b i l s raised with the mother. a. Between young i n the home cage. b. Between young i n the arena. c. Between strangers i n the arena. d. Between mother and young i n home cage. I five. AV I t jrj 3t> 4S SI 57 Q L . f W a . I 1 -1_ 47 33 3? -9S SI O f t X S CP Pitt 57 5 J -3 -/ - / A » I 27 33 39 4-f SI Si OPiYS Of P U f c 6 5 ftv&. 4 3 ^7 33 39 45" 47 t t . Pl.tW Figure 5* Number of interactions between gerbils raised i n i s o l a t i o n . a) Between g e r b i l s raised with toys. b) Between Kaspar Hauser g e r b i l s . <0 X j i j , J o Cr- C O To / 4 * a a 7-<£ o aJ U. d Figure 6. D i s t r i b u t i o n of durations, of play f i g h t s i n infant hamsters. 6s Figure 7. D i s t r i b u t i o n of durations of play and r e a l f i g h t s i n g e r b i l s . a. D i s t r i b u t i o n of r e a l f i g h t s i n juvenile g e r b i l s . b. D i s t r i b u t i o n of r e a l f i g h t s i n adult g e r b i l s . c. D i s t r i b u t i o n of play i n infant g e r b i l s . d. D i s t r i b u t i o n of play i n juvenile g e r b i l s . Figure 8. Average number of play and r e a l f i g h t s following latency periods. a. Play i n hamsters. b. Real f i g h t s i n hamsters. c. Play i n g e r b i l s . d. Real f i g h t s In g e r b i l s . 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
https://iiif.library.ubc.ca/presentation/dsp.831.1-0104778/manifest

Comment

Related Items