Ecologically differentiated patterns of aggressive and sexual behavior in two troops of Ugandan baboons Papio anubis.код для вставкиСкачать
Ecologically Differentiated Patterns of Aggressive and Sexual Behavior in Two Troops of Ugandan Baboons, Papio anubis J A M E S D. PATERS ON Department of Anthropology, T h e University o f Calgary, Calgary, Alberta ABSTRACT Two baboon troops from different ecological conditions - a thicket savanna in Queen Elizabeth Park, and a forest edge in the Budongo Forest - were studied during a 15 month period. Two different social structures were found and various levels of aggressive activity were observed, both among males and among females and juveniles. The patterns of female sexual behavior differed widely between the two troops. These patterns are examined, and the genetic and environmental factors involved in the determination of aggressive and sexual behavior among baboons are discussed. Two troops of African baboons, from two very different ecological situations, provided the data upon which this paper is based. One troop lives in a protected National Park, Queen Elizabeth National Park, in a thicket savanna ecology on the floor of the Albert Rift Valley, while the other troop is resident in a forest edge (mixed colonizing forest) and tree savanna/high grass ecology within the confines of the Budongo Forest Reserve. The animals of both troops correspond to the norm of "Olive Baboons," here ascribed to the species Payio anubis. The only local population variations noted were the presence of slightly larger, light colored eyelid patches in the Budongo groups and the existence of a gene for a shortened tail noted in the QENP group. Ecology-Queen Elizabeth National Park Queen Elizabeth National Park lies on the floor of the Albert Rift Valley a t the south end of the Ruwenzori, with the study area centered at latitude 0" 10's and longitude 30"O'E, and encloses most of the shorelines of Lakes Edward and George. The park encompasses two major ecological communities-the dry, deciduous Maramagambo forest, and two areas of thicket savanna a t the north and south ends of the park. The thicket savanna extends from the foothills of the Ruwenzori and the Crater Area southward to the MaramaAM. J. PHYS.ANTHROP.,38: 641-648. gambo with only a relative increase in the density of thicket formation and the appearance of a very few acacia trees along the Kazinga Channel. The flora and fauna of QENP are both rather restricted in variety. The thicket formations consist of a total of five species of bush, three of trees, and a number of ground plants and grasses. The fauna is likewise deficientelephants, buffalo, hippopotamus, waterbuck, kob, bushbuck, hyenas, lions, and the rare leopard being virtually the entire large mammal inventory. In spite of this the ecosystem is a balanced, savanna type one familiar to primatologists. The thicket savanna is only kept from proceeding to forest in the northern area of the park by the slight overpopulation of elephants. Papio anubis is discontinuously distributed over the park area: one troop in the Crater Area, two troops occupying part of the south side of the Kazinga Channel, and several troops along the edge of the Maramagambo. The baboon population in the area seems to be limited by the lack of adequate sleeping trees, Acacia seiberiana being the only suitable species in the area. The park normally has two wet and two dry seasons; March to May, and September to mid-November is wet, the rest of the year dry. Temperature averages about 22°C with fluctuations down to 10°C and up to 3 0 t " C . 64 1 642 JAMES D. PATERSON \ \ \ \ \ '. \ AGGRESSIVE AND SEXUAL BEHAVIOR OF PAPIO Ecology -B udongo Forest The Budongo Forest Reserve is situated i n Bunyoro Kingdom i n the area east of the Albert Rift some 20 km away from Lake Albert with the study area centered a t latitude l”45’N. and longitude 31”28’E. The land is a low rolling plain with many “sentinel” hills poking up irregularly, one of which is Busingiro Hill, the central area of this study. These sentinel hills are mostly rather rocky with poor soil and hence are covered with mixed tree savanna/high grass biome, and are surrounded by tropical rain forests of several different types within the Budongo and Siba Forests. Busingiro Hill seems to be in the process of being colonized by mixed forest; the Budongo is expanding at a steady rate now since elephants are no longer found i n the immediate area. Several hundred species of trees, bushes, herbs, creepers, etc., as well as a dozen or so species of grasses, exist i n this interface between forest and savanna. However, most of the nonprimate animal life has been hunted out of the area, both in the name of “control,” and by the nearby native agriculturists who practice poaching whenever possible. The main nonprimate animals are bushbuck and duikers; occasionally a warthog or buffalo is seen. This area normally has only one dry seasonDecember to February-and one long wet season with a slight lessening in rainfall during July, which is also the coolest month. Temperatures average about 22°C with fluctuations down to 5°C and up to 30°C. Rainfall occurs to an average of 1500 mm yearly, but with considerable variation. (Eggeling, ’47.) Troop Structures Troop “ A in QENP showed the now familiar hierarchical troop social structure, with a male dominance system employing the nine fully adult males in a rather straightforward unilineal sequence. The troop was constantly in a state of tension due to the activities of the males and the larger juveniles, who were already intent on the game of establishing their social rankings and often iritruded upon the preserves of the adults. There was also a constant state of combat among the hierarchy when females came into full estrus. 643 Troop “Bus-1” in Budongo evinced a rather different social structure in that there did not appear to be any sort of dominance hierarchy among the males or females. This troop was much less tense; there was virtually no fighting-never any over estrus females. The local human population, often including the observer, regularly provoked flight responses at ranges of up to 200 m. The information on this troop is based upon observations made in special areas which were more open than others, and also during hours when these areas were frequented by the animals. It was exceedingly frustrating to work in this environment since the troop when alarmed, would spread out over a large area and move quietly along a multitude of winding tunnels through 3 m-5 m high grass or dense forest undergrowth; it was difficult to maintain contact since the tolerance range of the troop was about 60 m-70 m , and the normal visual range under these conditions 10 m-15 m. Aggression Aggression-that is, intratroop threatening, harassing, and fighting-in troop “ A of QENP was one of the main social activities indulged in by this group when not pursuing primary subsistence actions. Patterns of aggression follow the well-known sequence described by Hall (’62), Hall and beVore (’65), Rowel1 (’66, ’69), and Washburn and DeVore (’61, ’63), in their papers on baboon behavior. Fighting and chasing were regular features of each day’s activity among all members of the group; adult males had the most obvious and noisy episodes, but adult females, juveniles, and larger infants were also involved. The most frequent and most violent fights between adult males occurred in those instances when there was only a single estrus female in the group. On these occasions, the first two or three hours of the day range would be nearly one continuous fight until the “consort for the day” was decided. It was on one of these occasions that the male we named Underdog was severely injured; his lower left lip was torn downward from the corner and hung loosely, and he lost the lower left canine and one or more of the premolars. Nevertheless, the following day, Underdog man- 644 JAMES D. PATERSON AGGRESSIVE AND SEXUAL BEHAVIOR OF P A P 1 0 aged to become consort to the single estrus female in the group. The Budongo troop, on the other hand, evinced a quite different pattern of aggressive behavior-virtually none at all. The usual amount of play chasing and open mouth threatening among the infants and juveniles occurred but there was none of this in the adult animals, except that which was directed against the observer. No intratroop fighting was over observed, but there were three instances of intertroop combat. Three troops of baboons have overlapping ranges on Busingiro Hill, one of the most important overlap areas being the feral mangoes and guavas near Busingiro House itself. During the rains there is no conflict between these troops; normally they do not come on the same days, and indeed three males migrated from troop 1 into troops 2 and Siba-one during October and November. This situation is much like that described by Rowel1 (’66). The intertroop conflicts occurred towards the end of a rather prolonged dry season in late February 1971. These conflicts were no doubt induced by the food shortage which was affecting all of the animals and humans in the area. This situation somewhat resembles that described by Maxim and Buettner-Janusch (’63). The pattern of these conflicts was chase-counterchase between the adult and large juvenile males of both troops, culminating in out-and-out fights between opposing adult males. Interestingly enough, the two males involved in the fighting during the conflict between troops 1 and 2 had both been members of troop 1 during most of the previous year. Sexual patterns The normal sexual pattern of female baboons in East Africa seems to be solicitation of a male, acceptance of the mount, head-turning over shoulder, lip-smacking, rigid posture during the male’s ejaculatory pause, vocalization of copulatory pants length of sequence depending upon the male’s maturity - and finally a run away from the male for 5m-25m. The male makes only one mount rather than a series, and usually follows the female and grooms her afterwards. This was the pattern observed among 645 the animals in the savanna of QENP, and the sequence was invariable. The female always panted and ran when a complete or nearly complete mount was performed upon her, even when the male was only an infant. I n addition, mountings were only performed on the ground; several times, a solicitation occurred in a tree and both baboons descended to the ground to copulate. Sexual tension was obvious in the QENP troop, especially when only a single female was in estrus. During the early stages of her swelling she would solicit from every male animal in the troop, and accepted mounts with infants, juveniles, and subadults, though the fully adult males were rarely interested in her unless she was the first estrus female to appear in some time. In the middle phases of estrus, the female was bound up in a daily consort pair relationship with an adult male, and it was at this time that most fighting was observed. Also at this time, male masturbation was observed on two occasions, but a possibly related action, “penis flicks” the rapid erection and loss of erection in a two-second cycle - was often seen in consort males while being groomed. In the Budongo troop the situation was somewhat different. The complete female sexual response pattern was deficient. The females rarely panted during a copulation, no matter what the maturity of the male, and the running away phase was often abbreviated to either a single step away or an immediate turning around to groom the male. Consort pairs were never formed but a “pseudo-consort’’ relation was noted occasionally. On three occasions, an estrus female and her pseudo-consort left the vicinity of the troop during the day range, and separated from it by up to 500 m ; on these excursions it was always the female who did the leading, the male tagging along submissively. This pseudo-consort relation did not evince the intensive and repeated sexual activity which the consort relation did in the savanna troop, in that copulation was rather infrequent on these sorties. There was, other than on these pseudo-consort occasions, no portion of a female’s estrus period during which she was reserved to the adult males. Even at the height of her swelling, she would accept mounting attempts by large infants, 646 JAMES D. PATERSON juveniles, and subadults, and the adult males did not seem to be interested in preventing such activity. Most copulatory behavior occurred during the early hours of the day, 0700 to 1000 hours, and was performed high in trees. Pairs never came to the ground merely to copulate. Most observed copulations occurred in end branches at altitudes of 10 m to 20 m . Some nursing females of the Budongo troops came into regular estrus when their infants were at the transitional phase, changing from black to brown coat color. This is rather different from previously described sequences of female estrus cycles (Hall, ’62; Saayman, ’ 7 0 ) , and would tend to reduce the period between births to about one year. I a m at a loss to explain this phenomenon except to postulate that perhaps it is social synchrony of estrus occurring in a n environment which permits it, since infant two’s are normally weaned and existing on their own in juvenile groups in this troop by the time they are a year old. This estrus synchrony may be analogous to the heat synchrony of the canids. In both areas there seemed to be a pronounced birth peak and a definite period of about three months when almost all of the females in the troops came into estrus OBSERVABLE Fig. 3 and were bred. It was during this period, February to April, that the above-mentioned nursing females came into estrus in the Budongo, though the phenomenon was not observed i n the QENP troop. DISCUSSION Each troop of baboons examined showed very different mannerisms, attitudes, and, to some extent, variations in social structure. In the process of trying to understand the reasons behind these differences it was determined that the differences could not be held at the foot of “genetic” distinctions, purely learned differences, nor even the differences in environment. In the end, the ethological view of behavior as expressed by Eibl-Eibesfeldt (’70, ’72) was eagerly seized upon and slightly modified to form a model (fig. 3 ) for the generation of variance in behavior sequence sets. In this model, the basic level is of species specific, genetically determined behavior sets, the features that all baboons of the Papio anubis type show in common. There is also a conditioning or modulating factor in the ecological environment which acts like a filter between the genes and the observable behavior. The ecology can modify the genetic behavior program by appropriate deletion or emphasis of some aspect of BEHAVIOR Behavioral model. AGGRESSIVE AND SEXUAL BEHAVIOR OF PAPIO a behavior sequence - all according to the requirements of successful adaptation to the particular ecosystem. The third portion of the model is that of group history and learned behavior, which puts the final idiosyncratic troop specific details onto the behavior sequence. This is the “proto-cultural” behavior which is individually learned and may or may not be passed on through observational learning to other members of a troop. It is also possible that new patterns of behavior can be engendered by a combination of learning capabilities and the ecological requirements which could then be inserted into the behavioral repertoire of the species. This flexibility would be particularly important to a species during the invasion of a new environment or during ecological change. Such malleability is obviously part of the capacity of Papio anubis and of Homo sapiens, since both have survived quite drastic ecological modification, and also have spread throughout numerous environments across Africa. It is felt that this model fully accounts for the differentiation of behavior sequences between these two troops, and with further work and cogitation, it could become a useful model for all other primates. 647 LITERATURE CITED Eggeling, W. J. 1947 Observations on the ecology of the Budongo Rain Forest, Uganda. J . Ecology, 34: 20-87. Eibl-Ebesfeldt, I. 1970 Ethology: The Biology of Behavior. Holt, Rinehart, and Winston, New York. 1972 Love and Hate: The Natural History of Behavior Patterns. Holt, Rinehart, and Winston, New York. Hall, K. R. L. 1962 The sexual, agonistic, and derived social behavior patterns of the wild chacma baboon, Papio ursinus. Proc. Zool. SOC. Lond., 139: 283-327. Hall, K. R. L., and I. DeVore 1965 Primate Behavior, Field Studies of Monkeys and Apes. In: Baboon Social Behavior. I. DeVore, ed. Holt, Rinehart, and Winston, New York, pp. 53-110. Maxim, P. E., and J. Buettner-Janusch 1963 A field study of the Kenya baboon. Am. J . Phys. Anthrop., 21: 165-180. Rowell, T. E. 1966 Forest living baboons in Uganda. J. Zool. SOC.Lond., 149: 344-364. 1969 Long-term changes in a population of Ugandan baboons. Folia Primat., 11: 241-254. Saayman, G. S. 1970 The menstrual cycle and sexual behavior in a troop of free ranging chacma baboons ( P a p i o ursinus). Folia Primat., 12: 81-110. Washburn, S . L., and I. DeVore 1961 The social life of baboons. Scient. Am., 204: 62-71. 1963 African Ecology and Human Evolution. In: Baboon Ecology and Human Evolution. F. C. Howell and F. Bourliere, eds. Aldine, Chicago, pp. 335-367.