-——- ‘5“— " v- . V t i- ‘ E - u- ' I-| c v‘ . .. . ' . . 3 . vw— ygjvjvfi' .wV w _ ‘ "_' ' ' . o .. . . 5......d-. - ..‘ u BEEMMMMM MEMEEMEMEMT m, THE YOUNG ' OFBENNETPSWAUABY -. .. WALLABIA MMEMMMMEA (MAMEMMMM momentum ' ThMEEE for. fine Degree of M.;s. MMMMMMSEAEE MMMEMSMM _ MMMMMREI‘ EELEM MMUMMMMM ‘ ‘ 3973. _' ' ' MmMWTWWWWI1 . may 3 1293 10716 116 . . deugan Stan ‘ University ABSTRACT BEHAVIORAL DEVELOPMENT IN THE YOUNG 0F BENNETT'S WALLABY, WALLABIA RUFOGRISEA (MARSUPIALIA: MACROPODIDAE) By Margaret Ellen Drummond The subjects of this study were two male and two female young Bennett's wallabies, Wallabia rufogrisea frutica, a Tasmanian subspecies. These were observed for ten weeks, for twenty minutes per day per young for five days a week. Each twenty minute observation period was divi- ded into five—second time bins and the behavior observed in each bin was recorded. Types and frequencies of behavior were determined from these data. The transition from the young's dependence on the mother to independence occurs in three stages: 1) the young is completely confined within the pouch; 2) the young emerges from the pouch for short periods but stays close to the female; 3) the young is always out of the pouch and is only with the female when nursing. The only sort of maternal behavior observed occurs during the second stage of independence; the female calls to her young to return to the pouch if it is out. After permanent pouch emergence the young engage in social interactions with other wallabies and generally exhibit adult-type behaviors. Sex roles are differentiated at pouch emergence. It is postulated that "beha- vioral birth" occurs at pouch emergence and makes the wallaby comparable to large eutherian grazing mammals in that wallaby young are precocial at pouch emergence and hence equivalent to ungulate young which are pre- cocial at birth. The long, intimate association between the wallaby mother and her young does not appear to entail much learning and Margaret Ellen Drummond behavioral interaction, as it does in a eutherian with protracted infancy, such as a primate. BEHAVIORAL DEVELOPMENT IN THE YOUNG OF BENNETT'S WALLABY, WALLABIA RUFOGRISEA (MARSUPIALIA: MACROPODIDAE) By Margaret Ellen Drummond A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Zoology 1971 In memory of the late Heine and Baby ii ACKNOWLEDGMENTS I wish to thank Dr. J. I. Johnson for his patient help and encou- ragement throughout this study. Also I appreciate the assistance in observing the animals of Michael Jaeger, Ripalda Krasnoborski, John Benson, and M. John Dwyer. The original colony animals were obtained through the kind coopera- tion of the Animals and Birds Protection Board of Tasmania. This research was supported by NIH Research Grant NS 05982, NIH Training Grant GM 01751, and NIH Facilities Grant IP06~FR0036. iii TABLE OF CONTENTS LIST OF TABLESOOOOOOOOO. OOOOOOOOOOOOOO .... OOOOOOOOOOOOOOO 0... LIST OF FIGURES ............... . .......................... ..... IntrOdUCtion ........... 0.00.0.0... ....... ......OOOOOOOOOOOO MethOdSOOOOOOOOOOOOOOO000......0.....0.........OOOOOOOOOOOOOOO subjeCtS O O O O O I I O O O O O O O O O I O O O O O C O O O O 0 O O O O O O O O O O 0 I O O O O O O EnViromnent O O ..... O O O O O O O O O O O O O O O I O O O O O O O O O O O O O O O O O O O 0 Observations O O O O O O O 000000000000 O O O O 0 O O O O ..... O O O O O I O O O Resu1tSoo ..... ......OOOOOOOOOOCOOOO OOOOOOOOOOOOOOOO 0.00.00... 1. The Transition from Dependence to Independence.... . Pouch emergence........................ 6 . Nursing and weaning.................... 13 . Mother—young interactions.............. 17 . Stages in the development of independence........................... 20 UOw> II. Social Interactions... ..... ........... ..... ....... III. The General Development of Adult Behaviors........ IV. Generalizability of Afternoon Observations........ DisCUSSionOOOOOOOOOO 000000000000 O ...... 0.00.0.0... ........ .0 Calling............................................... Pouch emergence........... ..... ....................... Ageing the young........ ...... ........................ Social interactions......... ..... ..................... BIBLIOGRAPHYOO ..... 0.00.00...0.0.0.........OOOOOOOOOOOOOOO... iv ... 3 450000 24 31 41 45 47 50 51 LIST OF TABLES Page Frequency of Social Interactions over Time for Bruce...... 28 Frequency of Social Interactions over Time for Esther..... 29 A Comparison of the Observed Frequencies of Selected Behaviors between the Afternoon Observations and the Twenty-four Hour ObservationSooooooo00000000000000...no... 42 Figure LIST OF FIGURES Frequency of Head In, Head Out, and Out g£_the Pouch over Time for EaCh Youngo.......OOOOOOOIIOOOOOOOOOOOOOOO.... Per Cent of Time Spent Out of the Pouch for Each YoungOOIOOOO......OOOOOOOO......OOOOOOOOOOOIIOOOOO ...... 0... Observed Probability of Grazing while in the Pouch, Grazing while out of the Pouch, and of Nursing for EaChYoungOOOOOOOOOOIOO00.0.0000.........OOOOOOOO0.0.0.0.... Frequency of Grazing over Time for Each Young Compared with Adult Females and with Adults of Both Sexes............ Frequency of Locomotion over Time for Each Young Compared WithAdUIt FemaleSOOOOOOOOOOOOOOO00.000.00.000...0.00.0.0... Frequency of Observing over Time for Each Young Compared With Adult FemaleSOOOOOOOO.........OOOOOOOOOOOOOOO00.0.00... Frequency of Lying Down over Time for Each Young Compared WithAdUIt FemaleSOOOOOO0......0.0......OOOOOOOOOOOOOOOOOOO. Frequency of Grooming over Time for Each Young Compared WithAdUIt FemaleSOOOOO...000............OOOOOOOOOOOOOOOI.I. Frequency of Standing over Time for Each Young Compared WithAdUIt FemaleSOOIOOOOOOOOO...OOOOOOOOOOOOOOOOOCOO ....... vi Page 12 16 33 35 36 37 39 INTRODUCTION The marsupial mechanism of reproduction enforces a different mother-infant relationship than that of eutherian mammals. The marsu— pial young is born in a highly embryonic state and must complete its de- velopment contained within the female's pouch. Thus the mother and her young have an extended period of close association before the young be— comes independent. Although much of the marsupial work in the literature has centered on reproduction, this being an area of most striking dif— ference between marsupials and placental mammals; very little work has been done on maternal behavior and the ontogeny of behavior in the young. Most behavioral information found in the literature is largely anecdo- tal and is incidental to studies on some other aspect of marsupial biology. Beach (1939) made some observations on a female Marmosa cinerea (a South American didelphid marsupial) with young. He tested the female for nest building behavior and retrieving of young; the female carried strips of paper in the tail or mouth to the nest box and pushed either her own young or new—born rat pups under her so they could attach to the nipple. The young were weaned and left the mother when their eyes Opened, although they returned to her if startled. There are several studies which deal with the development of marsu- pial young after birth, e.g. the quokka (Waring et. al.,1955), the short-nosed bandicoot (Mackerras and Smith, 1960), the marsupial mouse (Marlow, 1961), the red kangaroo (Sherman and Calaby, 1964), and the rat kangaroo (Tyndale-Biscoe, 1968). These give information on the age of 1 2 weaning and of emergence from the pouch but deal with any other behavior of the young only incidentally and do not consider the young once it leaves its mother. This literature does indicate that the MacrOpodidae, the kangaroo forms such as Bennett's wallaby, develop much more slowly than other marsupial groups. Macropod young go through a long period of transition from complete dependence on the female to complete independence, while other forms tend to be weaned and become independent as soon as they are fully furred and their eyes are Open. The lack of behavioral information is unfortunate, for Wallabia rufogrisea has considerable potential as a laboratory animal for corre- lative studies between neurophysiology and neuroanatomy and behavior in marsupials. It has a large brain for a marsupial, yet it is not an overly large animal to house. It is largely diurnal and apparently not averse to being observed, making it a good subject for behavioral studies. In addition, it reproduces readily in captivity. The purpose of this study is to explore the ontogeny of behavior in a species in which this has not been studied. This species is a repre- sentative of an entire order in which this area has not been investigated. An attempt will be made to find parallels and differences with the onto- genetic behavior patterns observed for eutherian mammals. METHODS Subjects The subjects were Bennett's wallaby, the Tasmanian race of the red— necked wallaby, with the subspecific name of Wallabia rufogrisea frutica. When this study was made, the Michigan State University population of these animals consisted of four adult males, four adult females, and four young. Two of the females — Hal (Bruce's mother) and Ida (Baby's mother) — arrived from Tasmania in October of 1968. Del (Esther's mo- ther) was born at Michigan State in the spring of 1967, and May (Heine's mother) was born here in the spring of 1969. The two females from Tas- mania are believed also to have been born and raised in captivity. The four young consisted of two males, Bruce and Baby, and two fe- males, Esther and Heine. Their precise ages are unknown. A pouch check on November 6, 1969, revealed all four adult females to have a young in the pouch. No further pouch checks were made, and the histories of the young are unknown until their size made their presence obvious when ob- serving the female. Thus it cannot be said for certain if the young seen on November 6 were the same ones later studied, or if any of these were lost and a new young subsequently born. Size and general behavior indi— cated that Bruce and Esther were the eldest and about the same age, with Baby being the youngest and Heine intermediate in age. Environment The wallabies are housed in a 59 foot by 109 foot outdoor enclosure with access to a covered outdoor shed and an indoor stall which is heated in winter. Except in winter the grass and other plants in the yard are available as food. The animals are also provided with a mineralized salt block, water, cold tea, lettuce, apples, raw vegetables, and vita- min paste on bread sandwiches. 4 The enclosure is part of one of the Michigan State University vete- rinary barns, and there are personnel around during working hours going into the enclosure every day. The wallabies are a favorite with sight- seers, and there is constant passing highway traffic as well. Thus the wallabies are exposed to a considerable amount of disturbance. It is im- possible to say what effect this disturbance combined with confinement has on their normal behavior patterns. Observations All of the data in this study are taken from direct observations of the animals. No experimental manipulations were performed; the obser- vations were of the animals' day-to-day pursuits. The observational technique was as follows: each mother and young pair (or each young, af- ter independence from the mother) was observed for twenty minutes a day. Each twenty minute time period was divided into consecutive five-second time bins. The twenty minute time periods were timed with a stopwatch, and the animal's behavior during each five—second time bin was recorded in a notebook with apprOpriately marked spaces. The animals were obser- ved for five days every week, resulting in a total of 100 minutes of observation per animal (or per mother-young pair) per week. The data were examined with these 100 minutes per week as the time base. Obser- vations continued for ten weeks, from May 11 to July 21, 1970. The above technique is modified from that used by Bombardieri and Johnson (1969) for observing opossums. Before I began the actual timed, data-taking observations, I spent about a month observing the wallabies to get generally acquainted with the types of behavior they exhibit. Thus when actual data—taking began, I had a general, yet flexible, sort of code in mind for recording ob- served behaviors. However the categories of behavior described in the 5 results section were not firmly delineated until the data were analyzed. The observations were made in the afternoon, generally between 3:00 P.M. and 6:00 P.M. Generalizability of these afternoon observations to other times of the day was tested in the following manner. The day was divided into twelve two-hour time blocks. Over a two-week time period observations were made in each of the twelve time blocks, in randomly assorted order (modified from Bombardieri and Johnson, 1969). Regular afternoon observations were also made for six days a week for this two- week period to provide an equal time base for the comparison of the two sets of observations. Statistical analysis indicates that behaviors observed in the after— noon are representative of behaviors observed throughout the day with respect to the kinds of behaviors observed and the amount of time spent engaged in those behaviors. This comparison will be discussed more ful- ly in the results section. The scores of three "second observers", each observing for one day, yielded a 96.5 per cent agreement with those of the principal observer for those days. RESULTS The observations obtained on the behavioral development of the young wallabies can be divided into three categories: those concerned with the transition from dependence on the mother to independence from her, those concerned with social interactions, and those concerned with the general development of adult behavior patterns. I. The Transition from Dependence to Independence In this category will be discussed emergence from the mother's pouch, weaning, and mother-young interactions and maternal behavior. A. Pouch emergence In looking at pouch emergence, three measures were used: time spent in the pouch with the head in, time spent in the pouch with the head out of the pouch, and time spent out of the pouch. To explain these cate- gories more fully, the young while in the pouch may have various parts of the body out - the whole head, ear(s), tail, hindlimb(s), forelimb(s) - or it may be completely inside the pouch. The 2229.32 the pouch cate- gory includes the young being completely in the pouch or having any part of its body out except the whole head. Any time that the young has its whole head or its head and forearms out is recorded in the £339.325 cate- gory. This 2239.12 or head gg£_dichotomy gives a measure of the amount of time the young spends attending to its external environment while it is still confined to the pouch. Since the young can generally have its head in or out at its own volition, the young animal is in a position to regulate the amount of input it receives directly from the environ- ment. (Occasionally the female will be lying down in such a way as to occlude the pouch opening, although a really determined young could pro- bably squirm enough to make her roll over.) Time spent out of the pouch is self-explanatory and is probably the most accurate available measure of the development of the young's independence from the mother. (The time of weaning would be the ultimate criterion of independence, but this is very difficult to determine. The young, when out of the pouch, nurses with its head placed in the female's pouch. Once the head is in the pouch, the observer cannot determine if the young is nursing or not.) Figure 1 shows the above three measures for each young wallaby, plotted over time. Bruce (Figure la) was already spending part of the Figure 1. Frequency of Head In, Head Out, and Out of the Pouch over Time for Each Young ——-——- Head in ------ Head out ——————o0ut g: the pouch 1003\0EC. acuu com .11 w w w w m .... mww ‘ Esfhef Bruce C O 01m 0 WW1W5WWbJoI 3.3.6.1 603 333?»,35: 00 of Observation Week 5 2003 \VS...~ ncvu sum 9 wuwwwmwumw \ w \“ // \\\s s I s s v r \ X. II IoJ Heme 9 u w u u w. n u w AUZQJnom 003 1.00%.; autism: 0 IO IO 80 Minnie} 05‘ Observntmn Weeks Figure 1 9 time out of the pouch when observations were begun. During Week 1 Bruce was out of the pouch 35 minutes of a possible 100 minutes. He was out for 48 minutes in Week 2 and from Week 3 on was never again observed to be in the pouch. The hgad_i2_and he§g_92£_measures for Weeks 1 and 2 are Egad in, 30 minutes and 24 minutes, respectively, and Egadnggt, 35 minutes and 28 minutes. These measures of course decline as a function of the increasing amount of time spent out of the pouch and drop out al- together when the young is finally out of the pouch all of the time. Esther (Figure lb) was not observed to be out of the pouch at all during Week 1, but was out for 80 minutes in Week 2, and was completely out from Week 3 on. This transition from always being in the pouch during Week 1 to always being out by Week 3 is even more abrupt than the graph indicates. The data point for Week 2 shows that she was out of the pouch for 80 minutes out of 100; actually she spent all 20 minutes in the pouch on day 1 and all 20 minutes out of the pouch for each of the next four days. Thus Esther's complete pouch emergence appears to have actually occurred overnight, but since it occurred in the midst of a five-day ob- servational unit, it does not show as such on the graph. The hgad'in_measure for Esther was 20 minutes in Week 1 and 6 mi- nutes in Week 2. The hg§d_22£_times were 80 minutes in Week 1 and 14 minutes in Week 2. These measures have both dropped out by Week 3. Heine (Figure 1c) was out of the pouch for very little time (0 to 4 minutes per week) for the first seven weeks of observation. During Week 8 she was out for 58 minutes and by Week 9 was observed to be out of the pouch all of the time. The hg§d_in_and Egad 225 measures vary over the eight weeks for which they are applicable. No pattern in this variation is observable; however the hgaduin_measure is consistently higher over the first seven weeks but drOps below the range of the head 10 gu£_measure in Week 8. The hgadugg£_measure for Week 8 is well within the range of the hgag_22£_measures for Weeks 1 through 7. Of course, by Week 8, time spent out of the pouch has increased considerably, affecting the head in and hgad.gg£_measures. Times for hggd_in,‘hggg.gu£, and gut_gf_£hg 22225 are shown for Baby in Figure 1d. Baby was found dead on the ground in the wallaby yard on day 5 of Week 8, so his record is incomplete. Figure 1d, for this rea- son, shows per cent of time per week a behavior was observed, rather than the absolute amount of time, to allow for there only being 80 minutes of observation in Week 8 for Baby. These data are still comparable directly to those for the other three animals, since absolute amounts of time based on 100 minutes per week is equivalent to per cent of time. Baby had not completely emerged from the pouch at the time of death. The cause of his death is unknown; a reasonable guess is that there was some difficulty with weaning. The possibility that this animal's beha- vior was not normal due to some changed condition before it died plus the fact that it died before pouch emergence make these data less infor- mative than those for the other three young. Baby was out of the pouch for some period of time in each of Weeks 3 through 8. Weeks 3 through 6 show a fairly constant but small amount of time spent out of the pouch (0.4 per cent to 3.2 per cent). During Weeks 7 and 8 he spent considerably more time out (26.3 per cent and 21.7 per cent). This may indicate that he was almost ready to emerge altogether from the pouch, but due to illness or general weakness did not show the rapid rise to complete emergence shown by the other young. The head in and head 925 measures vary over time in no particular ob— servable pattern. The hgad ig_measure is, however, consistently higher than the head out measure. 11 Figure 2 shows the per cent of time spent out of the pouch for each of the four young. Heine and Esther show the transition the most cleanly. They both changed from 0.0 per cent of the time observed out of the pouch to 100 per cent of the time observed out over a two week period. The whole transition for Bruce was not observed and Baby's death cut short his record. Behaviorally, of course, there is more to pouch emergence than the change in the amount of time spent in the pouch. -The behavior of the young during the transition period will be discussed in the sec- tions on nursing and weaning, mother—young interactions, and the stages in the development of independence. HOpefully, the amounts of time spent with the head in or the head out would have shown some consistent directional changes over time, in— dicating that as the animal grew older, it spent more time with its head out of the pouch, in contact with the external environment, even before it actually emerged from the pouch. Heine and Baby are the only two animals for which the h33d_i§_and hgad out measures are recorded over a number of weeks (Figures 1c and 1d). While a greater amount of time is spent with the head in the pouch than with the head out of the pouch while the animal is still in the pouch most of the time, the variation in the two measures show no observable pattern from one week to the next. There is no indication of an increase in the amount of time spent with the head out as the time of pouch emergence approaches for either Heine or Baby. During Week 1, the only week she was altogether in the pouch, Esther's head was out for 80 minutes and in for 20 minutes, a much higher .h£§§.22£ time than any shown by the other three animals (Figure 1). However, nothing can be inferred from this without a record of the head ‘13 and head out measures for the preceding weeks. Likewise, as Bruce was 12 wcoow somm How zooom man mo uso uaoam mEHH mo uamo uwm .N ouswfim Comvd>euu40 +6 3.003 0‘ h a s a h r m .4 . 1.1... :3 Inn]I| ”(~01 11111111 va+ww vuzbm e .2 3 a .9 .9. a 2 o >1==m / Wu. mm ”a . '- 13 already out of the pouch a good part of the time by Week 1 (Figure la), his Eggd in and head gg£_measures dr0p out rapidly and provide little in- formation. B. Nursing and weaning Another measure of the independence of the young from the mother is the time of weaning. As mentioned above, this is difficult to determine in these animals. When the young animal is inside of the pouch, the ob- server cannot determine if the animal is nursing or not. Even when the animal is out of the pouch with the head inside, one cannot state posi— tively that it is actually nursing. The following measures were used to provide some indication of the transition from nursing to grazing: time spent grazing while in the pouch, time spent grazing while out of the pouch, and time spent nursing while out of the pouch. To elaborate, grazing consists of eating any food item in the yard - grass and the various provided foods such as oats, bread, and raw vegetables. The young wallaby can graze when it has its head out of the pouch. When it is small, its grazing is somewhat con- trolled by its mother; she must be standing with her forepaws on the ground for the young to be able to reach the grass from the pouch. As the young grows, he is able to stretch out far enough to reach the grass with his mouth while in the pouch even if the mother is sitting on her hindlegs, which is the more frequent stance. (The mean time spent sit- ting on the hindlegs is 9.67 minutes per twenty minute observation and the mean time for standing on all fours is 5.21 minutes, based on seven- ty observation periods of adult females.) Young animals in the pouch were only seen to eat grass; that they were never seen eating any of the provided food is probably due more to never observing a mother with a pouch young who wanted to eat near enough 14 to any of the provided food for the young to reach it, rather than a lack of interest in such food by the young. Young animals out of the pouch seem to investigate anything that might be edible; various young were ob- served chewing on sticks, rags, paper, and a plastic ink pen, as well as eating the provided food items. The nursing measure is actually the amount of time the young animal was observed to have its head in the pouch while the rest of the body was out of the pouch. The animal may or may not actually be suckling in this position; thus the measure may be inflated. Figure 3 shows the time spent grazing while in the pouch, grazing while out of the pouch, and nursing, expressed as the observed probabili— ty of the behavior occuring during the amount of time per week the young animal spent in the appropriate position for it to occur. Each of the four young shows one major peak in the time spent nur- sing. This peak comes in the week before pouch emergence for Bruce, in the week of emergence for Esther, and two weeks before emergence for Heine. There is a peak for Baby in the week before his death, again hinting that he was about ready to emerge from the pouch altogether at the time of his death. It is possible that both this peak in nursing and the time of per— manent pouch emergence can be used as relative age determinants for the young. The nursing peaks, from Figure 3, would indicate that Bruce is one week older than Esther, and six weeks older than Heine and Baby, who are the same age. The times of permanent pouch emergence, also marked on Figure 3, would indicate that Bruce and Esther are the same age and that both are six weeks older than Heine. These determinants agree quite well with the aforementioned subjective impression that Bruce and Esther were the eldest and about the same age and that Baby was the 15 Figure 3. Observed Probability of Grazing while in the Pouch, Grazing while out of the Pouch, and of Nursing for Each Young Nursing while out of the pouch (4» indicates no time out of the pouch for that week). """ Grazing while in the pouch. ----- Grazing while out of the pouch. O-b 0.5 9.1+ 0.3 0.1 DJ 6.0 0.5 ox 0.3 0.1 0.0 0.5 9.9 o. 3 0. 3. 0.1 0.5 DJ! 03 O. 1 0.! 00° 16 " Nuroimfi Peak Brute Esfiner .-——-—-'\ I/ \\ / $Nur5'1n5 \’_,—-“~\- \ I Peak \\ / \ l :- HCinc ‘1» Nursing Peek l 1 3 H 5' b 7 9 ‘1 lo 1‘ Out Babw Jr Nut-91% Peak week: Of Observatlon Figure 3 l7 youngest. That Heine looked to be older than Baby may have been due to Baby being weaker and not develOping as fast as Heine. The other two measures, grazing in and grazing out, are quite va- riable among the four animals and do not present any recognizable pattern, except that the grazing ig_measure drOps out when the young emerges from the pouch. The decrease in the amount of grazing done by Esther in Weeks 8 through 10 (P = 0.0 for Weeks 8 and 10 and P = 0.06 for Week 9) does not necessarily indicate that she was not eating. The comparison of these data with the data for a twenty—four hour day during Weeks 7 and 8 (Table 3, page 42) showed that Esther grazed significantly more often during the twenty-four hour observations than during the regular afternoon observations. This indicates that for some reason Esther has a pattern of eating different from that of Bruce at least. Rather than nibbling throughout the day, she may concentrate her eating at one time of day. C. Mother-young interactions A third way to approach the develoPment of independence in the young wallaby is to look at the interactions between the mother and her young and at her maternal behavior, such as it is. Due to the long and intimate physical relationship which exists between a marsupial mother and her young after birth, especially among the macrOpods, one might ex- pect more behavioral interaction between mother and young than one ac- tually finds. Before the young emerges from the pouch at all and after it is out of the pouch all of the time, the mother generally ignores her offspring. While the young is in the pouch with its head out, the female may lick it on the head while she is grooming herself around the pouch area. This relationship in time between grooming herself and licking her young 18 suggests that she may be grooming the young as an extension of her own body. Occasionally the female may lick the young while it is near her while out of the pouch. The wallabies also scratch themselves as a grooming activity, but no female was ever observed to scratch her young. After the young is permanently out of the pouch and no longer with the mother, the mother and her young may sniff and paw at one another when they happen to meet. Sniffing and pawing are characteristic pat- terns of interaction between any two adult and/or independent juvenile wallabies. The female and her offspring appear to be interacting as two unrelated animals; there is no special mother-young character to this behavior. One very interesting pattern of maternal behavior and mother-young interaction does occur during the transition period, when the young is coming out of the pouch for short periods of time and generally stays quite close to the mother. Occasionally during this period, when the young is out of the pouch, the female will emit a characteristic call and the young will return to the female and climb back into the pouch. The call is a double clucking sort of noise, sounding as if the female were clicking her tongue against the roof of her mouth rapidly twice in suc— cession. To my ears, I can imitate her sound by doing just that, and once got Bruce to attend to my clucking at him. (This was after he had been completely out of the pouch for some weeks.) The female wallaby's cluck is, however, much louder than mine. This behavior on the part of the mother is variable among the four females. In the two weeks Bruce was out of the pouch part of the time, his mother called to him six times while he was out. Five times he re- turned to the pouch and the sixth time he approached his mother and put his head in the pouch without getting in. Once he returned to the pouch 19 without a detectable signal from the female. Once Esther was first seen out of the pouch, she was not again ob- served to be in the pouch. Her mother was never heard to call to her, and Esther was not seen to try to re-enter the pouch. Whether the fe- male's never calling Esther was due to Esther's rapid transition from being in the pouch to being out, or her rapid transition was due to her mother's never calling to her to return is a moot point. Anyway, among the four mother-young pairs, Esther's transition to independence is un- usual, as is her mother's not calling to her. Heine was in and out of the pouch for eight weeks before she came out permanently. During this time, her mother was heard to call twice to her. Once Heine was out and returned to the pouch. This instance was unusual in that the female clucked repeatedly for about 15 seconds be— fore Heine re-entered the pouch and continued to cluck for 5 seconds af- ter the young was in. Usually a female gives only one double cluck. In the second instance of her mother's calling, Heine was in the pouch with her head out and pulled her head into the pouch in a response to the fe— male's call. This time the female gave only the usual one call. Heine was also observed to re-enter the pouch twice without a call from the mother. Baby had been coming out of the pouch for short periods of time for six weeks before he died in the eighth week of observation. During this time he re—entered the pouch nine times in response to calls from his mother and eleven times without an observable signal from her. These high figures in comparison with those for Heine, who spent a comparable number of weeks in the pouch during observation, are perhaps due to the fact that Baby came out of the pouch more times during the transition period. Compared with Heine (Figure 2) over the first six weeks of 20 observation, for instance, Baby spent comparable amounts of time out of the pouch; however the amount of time per incident of being out was gene- rally shorter for Baby. Baby averaged 0.4 minutes duration for each time out while Heine averaged 4.4 minutes duration. Baby was out thirteen times while Heine was out four times over the first six weeks of observa— tion. Baby's mother also showed one instance of repeated clucking in cal- ling her young. She clucked for about 10 seconds before Baby regained the pouch, at which point she st0pped clucking. Baby had immediately attended to the female's call but ran about for some time before he mana- ged to find the female and the pouch. Presumably the female's call is an alarm signal serving to bring the young back to the safety of the pouch when the mother has cause for alarm or sees a potential danger. However it was rarely apparent to the obser- ver what stimulus caused the female to call to the young. Out of seven— teen instances of the female calling, only three followed some sort of disturbance obvious to me. Bruce's mother called to him once as a air— plane flew overhead, once as a motorcycle went by, and once as several sheep rapidly approached the fence between the wallaby yard and an ad- joining pasture. If the female is lying down, standing or grazing with the forefeet on the ground, or sitting with the tail between the legs in a resting po- sition, and is aroused to call to her youngster, she will rise to stand on the hind legs in a more alert, attentive position. Also this posture allows the young best access to the pouch. D. Stages in the develOpment of independence From the data presented on pouch emergence, weaning, and mother— young interactions, it appears that there are three periods associated 21 with the development of independence in the young wallaby. There is the time period during which the young does not emerge at all from the pouch, the time period when the young is out of the pouch part of the time, and the final time period in which the young is no longer in the pouch at all. There are different behavior patterns associated with each of these sta— ges, and a description of how the young actually behaves during each stage is in order. While the young is still in the pouch all of the time, it is presu- maby incapable of surviving apart from the mother, and is much more a part of her than a separate entity. Nevertheless the young is more than a passive passenger. When the young is completely within the pouch, it sometimes moves around, often quite actively, as evidenced by motions in the pouch region of the female. The movements are sometimes quite irregular, as if the young were shifting its position in the pouch; at other times they are more regular, as if the animal were scratching. Especially as the young grows larger, various parts of the body be- sides the head may be out of the pouch. The tail may be hanging out, or the tail and a hind foot. Sometimes an entire hind leg is extended out of the pouch in an outstretched position. In these positions the animal must be oriented upside down in the pouch. When the young has the head out it is generally awake, although oc— casionally it will be asleep or resting, with the head drooping and the eyes closed. The young can graze with the head out, cr0pping off the grass with its teeth. Young were not observed to manipulate food items with the forepaws while in the pouch, as adults and independent juveniles may be observed to do. The young often investigates the ground with its nose, although when the mother is on all fours grazing, it is difficult to distinguish ground—nosing from grazing in the young. 22 The young may have the forepaws as well as the head out of the pouch. In warm weather the wallabies often lick their forearms; these become damp with saliva and presumably help to cool the animals by evapo— ration. The young wallaby in the pouch will do this on a warm day; in such weather it must be especially warm inside the pouch. The young may have the head either in or out for a considerable time, on the order of minutes, or one may pop its head in and out quite frequently. The mean duration of having the head in the pouch is 2.09 minutes and the mean duration of the hgadflgug position is 2.41 minutes, for all four young combined. The range for the hgad lg measure is 5 se- conds to 20 minutes and that for the hgad.ggg_measure is 5 seconds to 16 minutes 10 seconds. It is usually impossible to recognize any event which may cause the young to withdraw the head into the pouch. One notable exception is Heine's pulling her head in as a response to her mother's cluck, as men- tioned above. If the mother starts to hop while the young's head is out, the young will generally leave the head out. Sometimes the young will pull its head in as the female hops, often emerging again when the female stops. For all of the young, heads remained out 154 times as the female began to hOp and were pulled in 33 times at the onset of locomotion. If the young has the head in, it will remain thus during locomotion by the female. When the young wallaby begins to emerge from the pouch, it, of course, can exhibit a greater range of behaviors. During the period in which the young is only out of the pouch part of the time, it stays quite close to the mother. If the female moves more than a few feet, the young will follow. Very rarely during this period would one member of the mother-young pair be out of the observer's range of vision while if \Il' 23 watching the other member of the pair. The one instance of this occu- ring was that Heine was not with her mother for about 4 minutes one day in Week 7, the week before she was permanently out of the pouch. During these 4 minutes Heine was inside the barn, the mother having gone into the yard. Heine was nosed and pawed by a large male; the mother then re- turned tO the barn and Heine re-entered the pouch. The female was not heard to call to Heine, and it is indeterminable if she returned to the barn in search of her youngster. When the young is out of the pouch, it is generally active: hOpping in the vicinity of the mother on two or four feet, sniffing objects on the ground, scratching, putting its head in the pouch for brief moments. Comparisons of activity between young animals and adults will be dis- cussed in Section III. The young seems to fall out of the pouch rather than to climb out. The pouch Opening or the pouch wall is under muscular control by the fe- male. As she relaxes these muscles, the pouch opening enlarges and the young spills out onto the ground. The young generally gets up almost immediately from where it landed on the ground. One exception to being dumped is Bruce who was once observed to back out of the pouch by him- self while his mother was lying down on her side. The young re—enters the pouch by climbing in head first. Actually it must sort of somersault in, as it often appears right side up with the head out very soon after it climbs into the pouch. There is no ob- servable evidence that the female wallaby either helps or hinders the young when it tries to re-enter the pouch. After the young is permanently out of the pouch, it spends progres- sively less time in the proximity of its mother. For instance, Bruce, during his first week altogether out of the pouch (Week 3), was with his 24 mother the first and fourth days of the week, but not the other three days. After that, except for the time spent nursing, he was not near his mother except for seemingly chance encounters. Esther, who was in the pouch the first day of Week 2 and out the other four days, was not with her mother on days 2, 3, or 5 and was not with her mother except to nurse after Week 2. Heine likewise was not with her mother except to nurse after emerging altogether from the pouch. The behavior of the young af- ter permanent pouch emergence will be further discussed in Section III on the general develOpment of adult behavior patterns. II. Social Interactions An important part of the develOpment of a young mammal is his in- tegration into the group. Although wallabies do form dominance hierar- chies (LaFollette, 1968,1971), their social organization does not seem highly complex and the animals spend very little time interacting with one another. Even so, a developing wallaby would be expected to begin to interact with adults other than its mother, as well as with other young, at some point in its development. Three types of social interactions among wallabies can be distin— guished: aggressive, sexual, and neutral. Aggressive behavior is gene- rally initiated by a male toward another male or toward a female. The aggressor paws the second animal about the head and shoulders and growls. The second animal generally retreats, ending the encounter. Although actual fighting does occur (LaFollette, 1968, 1971), it was not observed during this study. In sexual interactions, the male is again the initiator, approaching adult females and the young of both sexes. Sexual interactions are cha- racterized by several behaviors in the male, any or all of which may be present during an interaction. The male snakes his tail back and forth 25 on the ground and noses the female's vaginal opening (or the anal region in a young male). The male may nose the female from behind at the base of her tail or may nose her from the front. For this reason it is often difficult to determine if the male is nosing the pouch region or the va- ginal area of the female. The male may clasp the second animal from behind around the shoulders or the rump, in an attempt to mount. The male has the penis everted. COpulation was never observed. Male advances were vigorously re— buffed: adult females growled and pawed (an aggressive pattern) at males who approached them sexually. Sometimes the male retreated; sometimes he persisted and it was the female who left. In general, young wallabies simply retreated from the male. Males were more persistent in sexual in— teractions than in aggressive ones. A male often pursued a female or a young for several encounter-retreat sequences. The estrous cycle for Wallabia rufogrisea is given as 30 to 31 days in length (Sharman, Calaby, and Poole, 1965). No attempts were made to determine estrous cycles in the present group of animals. However one incident is noteworthy here: just two days before Esther was permanently out of the pouch, three of the adult males spent almost an entire obser- vation period in pursuit of the mother (with Esther remaining in the pouch). The female was not at all interested and kept running from the males. Perhaps she was coming into estrus at this time; although she was behaviorally unreceptive, the males were definitely attracted to her. There is evidence that in some macrOpods, at least, the time of pouch emergence by the young is related to the reproductive cycle of the fe- male. The exact nature of this relationship has not yet been determined for W. rufogrisea. Neutral interactions are a nose-to-nose type of encounter, or some 26 variation of this. The basic encounter consists of two animals putting their noses together in sort of an Eskimo kiss. This may serve a similar function - identification and recognition - as the kiss described by King (1955) for the black-tailed prairie dog, Cynomys ludovicianus, and by Rood (1970) for the desert cavy, Microcavia australis. In the wallaby, this is often a mutual behavior; it cannot be observed which animal ini— tiates the contact. Sometimes one animal definitely noses toward another; the other may respond by nosing back or may not react at all. Sometimes two animals nose toward one another without making nasal contact; they may be up to two feet apart and do this. This does appear to be a gree- ting or recognition interaction; it is termed neutral because it generally arouses no aggressive or retreat response as do the other two categories of interaction described. Not all instances of contact between animals can be termed social interactions. The animals may graze, lie, or stand in very close proxi- mity without seeming aware of one another's presence. A moving animal may brush or bump another in passing, with no response from the animal being touched. Despite the fact that three categories of interaction can be defined, it is often difficult to determine precisely into which category an ob- served interaction should be placed. Therefore some of the interactions observed may have been misclassified, but hOpefully any trends and con- clusions are still valid. Including social-type interactions with his mother, Bruce was in- volved in 20 aggressive encounters, 6 of which he initiated, 13 of which were initiated by others, and l in which no aggressor could be determined. Out of 8 sexual interactions, Bruce initiated 7 and was ap— proached once. He was also involved in 27 neutral encounters. Table l 27 shows the frequencies of these three types of encounters over the ten weeks of observation. No change in frequencies is apparent after perma— nent pouch emergence (Week 3). There was also no observable change in frequency between being the object of aggression and being the aggressor over time. As mentioned in the section on mother—young interactions, after permanent pouch emergence, young wallabies and their mothers seem to interact as unrelated individuals, except for nursing by the young. This is evidenced by Bruce's social interactions with his mother. Bruce initiated three aggressive encounters with his mother while she initiated two toward him. He also approached her twice sexually - sniffing her va- ginal region. There were three neutral encounters between the two animals. Bruce's behavior also hints that young males may initiate sexual in- teractions as soon as they begin to emerge from the pouch. Bruce was first observed out of the pouch during pilot Observations at the end of March. While out he jumped at his mother's head and back in what may have been an attempt to mount. Esther was the recipient of 12 aggressive approaches and 15 sexual approaches. She did not initiate any aggressive or sexual encounters, and was involved in 51 neutral encounters. Frequencies of these encoun- ters over time are given in Table 2. Again there seem to be no trends which develop over time after permanent pouch emergence (Week 3), except for perhaps a decrease in interactions in Weeks 8 through 10. This parallels the decrease in eating during times of observation as described above, indicating a general lessening of activity during the afternoon period in the latter weeks of observation for Esther. Since Bruce and Esther both emerged from the pouch at the same time and are presumably about the same age, their respective interactions with 28 Table 1 Frequency of Social Interactions over Time for Bruce Frequency of Encounters: Weeks of Observation Neutral Sexual Aggressive l 1 1 4 2 O O 2 3 2 0 2 4 1 0 0 5 3 1 1 6 3 l 1 7 7 0 3 8 4 4 4 9 3 0 2 10 3 1 1 Totals 27 8 20 29 Table 2 Frequency of Social Interactions over Time for Esther Frequency of Encounters: Weeks of Observation Neutral Sexual Aggressive 1 0 0 0 2 3 1 2 3 9 2 2 4 7 2 1 5 11 5 2 6 8 4 l 7 5 1 3 8 1 0 0 9 5 0 0 10 2 0 1 Totals 51 15 12 30 other animals can be compared on the basis of sex. Bruce was involved in more aggressive encounters and fewer sexual ones than Esther (Tables 1 and 2). Although usually the object of aggression, Bruce was on oc— casion the aggressor. Esther was always the object of aggression. Like- wise, Bruce was generally the initiator of sexual approaches, while Esther was always the approached. Esther was involved in more neutral encoun- ters than Bruce (51 for Esther to 27 for Bruce). Of these, Esther was involved in 40 encounters with males and in 11 with other females. This may indicate a sexual component to neutral interactions in that males seek to interact with a new female in the group, such as an adolescent young. Bruce was involved in 16 neutral interactions with other males and in 10 with females. Data on the frequency of neutral encounters by sex for adults would be helpful but is not available. Heine, although emerging from the pouch much later than Bruce or Esther, was the object of 7 aggressive advances and 15 sexual ones. She was also involved in 11 neutral interactions, all of which were with males. Social encounters being fairly rare events, Baby was not out of the pouch enough to interact a great deal. He was the object of one sexual interaction and was involved in one neutral encounter. Both interactions occurred in the week before his death. In general, then, the young are socially involved with the adult members of the group and each other when they emerge from the pouch. Age of sexual maturity for these animals is unknown, but their sex roles seem to be differentiated at the time of pouch emergence: males being involved in aggressive encounters and less frequently in sexual encoun- ters, and females being the objects of sexual and aggressive encounters. 31 III. The General Development of Adult Behaviors One way to measure the maturation of the young is to look at the amounts of time they spend engaged in selected behaviors compared with adults. Behaviors looked at in this light were grazing, locomotion, and various postural positions. Grazing has been previously defined to include eating various pro— vided food such as oats, vegetables, and bread, as well as actually eating the grass in the yard. There are two means of locomotion used by the wallabies; these have been combined in measuring their frequencies. The first is hopping on the two back feet, with both feet leaving the ground simultaneously. It is the more rapid pattern and is used more for sustained locomotion. The second means, stepping, uses all four feet, the two front feet advancing together, with the hind feet then brought up to the forefeet. This is a more leisurely gait and the animal generally takes only one to three steps in a bout of stepping. There are four stationary positions: observing, standing, the grooming position, and lying down. In the observing position, the ani- mal stands upright on the two hind feet. It may actually seem to be ob- serving the surroundings, turning the head from side to side and moving the ears; or it may stand motionless, seemingly oblivious. For this reason, observing is perhaps a poor designation for this category, since standing on the hind feet seems to be a resting position as well as an alert position. In the standing position, the animal is on all fours. This is per— haps also a resting position. In the grooming position, the animal is sitting down with its hind legs stretched out in front, and its tail between its legs, also out in 32 front. In this position the animal often grooms itself, scratching with its forepaws or licking and nibbling its fur. The animal may also just sit in this position. Grooming - scratching, licking, and nibbling - also occurs in the observing position. When lyinquown, the animal lies on its side, with all four legs on one side of the body. Occasionally the animal will graze in this posi- tion, if there happens to be some nice grass growing next to its mouth. The time spent engaged in the above behaviors or positions after pouch emergence for the three young which permanently emerged from the pouch was compared with the average amount of time spent in these beha— viors by the females who were Observed with their young until pouch emer— gence. A total of seventeen weeks of observation of females was used in the averages. Grazing frequency can also be compared with previous Ob- servation data on these animals (Johnson, unpubl.), but the other catego- ries are not comparable to previous data due to differences in the defi— nitions of categories. Unfortunately the behavior of females with large pouch young may not be entirely representative of the average behavior of the total adult pOpulation. Bruce and Esther were compared with the adult females for the eight weeks they were out of the pouch and Heine was compared for two weeks. These comparisons are shown in Figures 4 through 9. Figure 4 shows the amount of grazing the young did in comparison with the adult females of this study as well as with data on six adults observed at the same time of day in the summer of 1967 (Johnson, unpubl.). The adult females fed an average of 17 minutes per week out of a pos- sible 100 minutes (observed probability of grazing - 0.17). The observed probability of grazing by adults in the summer of 1967 was around 0.30 (Johnson, pers. comm.). 33 a» Brute if. Esther -------- 20.3 ' p--_--—-\ Haihg ~—--——.._ 6 .A a $0.). '0 1 U > :304 n .3 £) cs 1 1 3 M 5 s ? s 9 m Week: of Obscrwttion Figure 4. Frequency of Grazing over Time for Each Young Compared with Adult Females and with Adults of Both Sexes 1.) Observed probability of grazing by six adults in summer, 1967. 2 ) Observed probability of grazing by four adult females in the present study. x Indicates point of pouch emergence. 34 In general the amount of feeding done by Bruce and Esther fluctuates around the average of the adult females observed in this study. Both the two young and the four adult females spent less time eating than did the six adults observed in 1967. I cannot explain this difference; perhaps it is not significant. The amount of time Esther spent eating declines considerably in Weeks 8 through 10. As mentioned before, Esther seems to have a different eating schedule. Perhaps varying eating schedules among individuals account for the differences in amount of time spent feeding between 1967 and 1970. Nursing is most frequent right around the time of pouch emergence (Figure 3); therefore one might expect the amount of grazing to be lowest at the time of pouch emergence and to increase thereafter as the amount of nursing declines. This does not seem to occur, at least for Bruce and Esther. Other than Esther's perhaps developing an eating pattern related to time of day, there seems to be no change or development in feeding be- havior over time as the young animal ages. Heine was only observed out of the pouch for two weeks; during this time however she showed very little time spent grazing. As Figure 3 shows, she also spent very little time nursing during this period. Al- though no comparisons were done for Heine as to time of day when behaviors occurred after pouch emergence (Table 3), it is possible that she, like Esther, ate at a different time of day. Observed probabilities of locomotion (combined hopping and stepping) are shown in Figure 5. The probability of locomotion for adult females in this study was 0.02. Probability of locomotion for the three young is quite comparable to that of the four adult females. Locomotion is thus a relatively rare behavior for these animals. Figures 6 and 7 show comparisons for observing and lying down 35 ggaob :i o °.°H t a. ‘ 1 g no; 5 U n .3 C>oee a 1 3 ‘1 5' b 7 U 1 IO (flecks of Observatton Figure 5. Frequency of Locomotion over Time for Each Young Compared with Adult Females 1.) Observed probability of locomotion by four adult females in the present study. x Indicates point of pouch emergence. 36 Obscrvca‘ Prohebi litq 0.6 A Bruce I \ 9'5 ’1’ ‘\ Esther -------- I ‘\ 1' \ ' ._-_-__. _____l R I ~ Heme o.» 0.3 0.]. OJ cal l 1 3 ‘7 5 6 '1 S ‘7 IO (Jack: of Observation Figure 6. Frequency of Observing over Time for Each Young Compared with Adult Females 1.) Observed probability of observing by four adult females in the present study. x Indicates point of pouch emergence. 37 0.: Bruce 5’; 55m"- ...... ;;Qb d .0 9 a. 0.11 a‘ u 3 0.1 0 fl .9 O 0.0 (deck: 0% ObservatEOA Figure 7. Frequency of Lying Down over Time for Each Young Compared with Adult Females 1.) Observed probability of lying down by four adult females in the present study. .X Indicates point of pouch emergence. 38 positions. For the adult females, the average probability of observing was 0.44 and of lying down was 0.14. Both Bruce and Esther show similar marked differences when compared with these figures. Through Week 7 Bruce and Esther approximate the probabilities of the behaviors occurring shown by the adult females for both observing and lying down. However after Week 7, lying down sharply increases for Bruce and Esther and observing shows a corresponding drop for the same time period. A possible explanation for this is the weather. Weeks 8 through 10 of observation were the first three weeks of July and the weather was generally quite warm - warmer than the preceding weeks of observation. If observing is often a resting posture, and granting that lying down is such, lying down might replace observing as a function of warm weather. No adult females were observed during Weeks 8 through 10 so it cannot be de- termined if they showed a corresponding shift in behavior. However it was my impression that the entire group spent a great deal of time lying down on warm afternoons. Also Heine (Figures 6 and 7) shows less time observing and more time lying down than the averages for the adult females. Comparisons for the grooming position are shown in Figure 8. Obser- ved probability for this position in the adult females was 0.04. The three young all show much higher figures than this. Also time spent by Bruce in this position generally decreases over time, while time spent by Esther increases. Heine also spent much more time in this position during the two weeks she was out of the pouch than the average for the adult females. Figure 9 shows standing behavior. Observed probability for this po— sition in adult females was 0.13. All three young spent considerably less time in this position than did the adult females. Thus, in general, the young resemble the adults more in the types 39 Bfute Es+Mer----- -- 9 .c it‘s Heme -—-—-— 9 v’ X P ,1 Oh served Probabil p o O F' {t ldccks 0? Observation Figure 8. Frequency of Grooming over Time for Each Young Compared with Adult Females 1.) Observed probability of grooming by four adult females in the present study. X Indicates point of pouch emergence. 40 Bruce if Esther ------- .9 3°91 Heine —--—-- o L a. 1 .304 u > b a vice .0 0 1 a 3 ‘1 I 6 1 s 9 lo 1ueeks Of ObSCTVKtiOfl Figure 9. Frequency of Standing over Time for Each Young Compared with Adult Females 1.) Observed probability of standing by four adult females in the present study. x Indicates point of pouch emergence. 41 of behavior observed rather than in the frequencies of those behaviors. Some of the differences in frequency, such as in lying down and observing, may be attributable to the weather. Others, such as standing and grooming, remain unexplained, except to say that the more time an animal spends doing one thing, the less it can spend doing another. Also, as evidenced by the grooming position frequencies for the young especially (Figure 8), individual differences may be great. Thus comparisons of highly variable individual data with an average of several animals may not be particularly useful. It is difficult to say if any changes in behavior occur with age. Esther's feeding schedule shifted as she got Older, but it cannot be said whether or not this was a function of age. Amount of time spent in the grooming position (Figure 8) changed over time for both Bruce and Esther; but since the changes were in Opposite directions, they do not indicate any one directional trend over time. Standing and locomotion did not observably change over time (Figures 9 and 5). Only lying down and observing (Figures 6 and 7) show any consistent directional changes over time; as mentioned before, this may be more a function of warm weather than of changes in behavior with age. More data, especially on young and adults over the same time span, will be necessary to determine when and how the young attain adult behavior patterns. IV. Generalizability of Afternoon Observations Table 3 presents a statistical comparison (Student's t—test, two- tailed) of the afternoon observations with the twenty-four hour observa— tions conducted during Weeks 7 and 8 of observation (June 22 to July 6). Different behaviors were used for some of the young since they did not exhibit the same behaviors during the two weeks due to differences in age and therefore in stage of behavioral develOpment. 42 ma 1 we spam NN n we maamm NN n we Hugumm mm u up mosum "Eowmmum mo momuwmo dmmE wfiu mo HOHHO whmvcmum fl Mm Ho>oa Nm um Mansfimaamam u M uanMMHawfim uoz u m: fiusom we m.oJ.a;vm.o MH.o Hm.H mm.m No.H Hm.m 6;“ no “so we a.o.va;.m.o mo.o ON.H ma.m BM.H “0.x “so same we a.ou.agvm.o me.o «A.H «H.OH we.H mw.a cH same spam we m.o..a;.m.o Nm.o ~0.H mo.q mm.a oe.m “so same we au.m.o no.0 me.~ om.w mm.~ NH.¢ aH same sense we ~.o.va.vfi.o HN.H ms.~ HH.OH me.H Hw.~ csoa wcfiea ma s.o..ag.~.o mo.H mH.H mo.m me.o oe.H wansoouu M mo.o..a..~o.o Ne.~ mm.o me.o am.o oo.e mafiumuo ma s.od.ar.m.o oo.H mm.H me.m GM.H Rm.m wca>u6mpo smegma ma m.ou.a.vm.o as.o Hm.H «w.m o~.~ o~.m neon wanes ma N.ou.a.va.o mm.H HM.H me.m ms.o Hw.o waneoouu ma a.o..a_.m.o Ho.o ew.o mm.m no.H mo.e wcfiumuo we m.ou.au.m.o mH.o m~.H mH.a mq.H ea.“ wan>ummno moose hdHHHDNfiOHm ODHm>lu Mm Cocaumum< Mm Mdom QN HOH>m£wm HmEHfi< UOHHQW COHUN>H0wDO\mQHDQHS meowum>uomno usom usomlmucoza on» was mCOfium>uomno noosuoum< may somauon muoa>mnom mmuomamm mo mmfioamaumum vm>ummno mau mo confiummaoo < m mHan 43 Only one behavior for one animal — grazing by Esther - showed a significant difference between the two sets of observations. Esther ate less in the afternoon than at other times of day (0.02£.p