A Case of Infant Carrying by an Adult Male Chimpanzee in the Budongo Forest
H. Notman¹ and J. Munn²
¹ Department of Anthropology, University of Calgary.
² Department of Archaeology and Anthropology,
Australian National University.



Introduction
Observations of chimpanzee males kidnapping and killing conspecific infants are commonplace. In many cases, infanticide is succeeded by cannibalism (1). While not all kidnappings result in infanticide and cannibalism, observations of chimpanzee males subsequently "caring" for stolen infants are rare, although they have been reported in other primate species (2). Despite the coercive manner in which infants might be attained, such instances in which there is a shift in primary caregiver from the mother to another older individual have been loosely described as "adoptions" (3), or "transient adoptions" when the shift is temporary (4). Depending on the age of the infant being held by the male, the end product of a kidnapping and adoption may essentially equate to infanticide; i.e., unweaned infants that are not returned to their mothers within a short period of time are likely to die from starvation or dehydration. The proximate causes of transient adoptions of infants by adult males are unclear, although it has been proposed for some species that infant carrying by males may function as a "buffer" from aggression by other males (5).

The following observation concerns the temporary carrying and "care" of a newborn infant by an adult male from the Sonso community of the Budongo Forest, Uganda.

Observations
Observations of this incident were made in December 1999. On December 13 at 09:10, Jambo (JM), a high-ranking adult male, was spotted resting on the ground while holding a newborn male infant. The infant's eyes were closed, its body very small, and body hair sparse. Several other chimpanzees were present and were behaving in an excited manner, but no particular female chimpanzee appeared distressed or anxious in a way that would indicate she was the victim of an infant kidnapping. The infant was producing high-pitched squeals and whimpering, and JM responded by "cuddling" the infant closer to his chest with his arms, although the infant was able to grasp JM's chest hair.

Throughout the day, JM carried the infant on his chest, and occasionally supported it with his arm by walking tripedally. During resting periods, the infant tried to suckle JM. When JM was moving, the infant screamed intermittently, suggesting it was experiencing pain or distress. At 18:46, JM bedded down with the infant.

On December 14, JM left his bed at 06:25, with the infant who was now clinging very weakly with one arm, but still screaming forcefully when moved. JM held the infant with one arm near his crotch when he walked, and carried it with his foot when climbing. No individuals were showing any interest in JM or the infant. JM paid little attention to the infant other than to carry it, and to occasionally prod or lightly groom it when it lay on his chest. By mid-afternoon the infant was totally listless and needed to be fully supported by JM's arm. This appeared to hamper him considerably and he was unable to keep up with other individuals in his party. Despite the infant's listlessness, it still squealed forcefully, though less often, when moved. JM again bedded that night with the infant still alive.

On December 15, JM was not found until late morning. The infant appeared to be dead, although JM still carried it. No indications of physical injury were apparent on the infant. JM poked at the infant periodically as it lay on his chest, but otherwise ignored it. JM was not found by observers in the afternoon, and was not seen until the next day when he was no longer carrying the infant. No fecal samples were collected to determine if JM had consumed the dead infant.

Discussion
This report concerns the carrying and limited "care" of a newborn infant by a male chimpanzee for at least two days, until just after the infant's death. JM was found with the infant well within the community home range, and the behaviour of the surrounding group members on the morning of December 13th suggests the acquisition of the infant had occurred shortly before our discovery of the group. Alternatively, other chimpanzees may have just become aware of JM's infant and were responding accordingly. We therefore have no way of knowing whether the infant was born to a female from within the Sonso community.

The proximate motives for JM's snatching and subsequent carrying of the infant are also unclear. It is possible that JM was initially motivated by infanticide but then aborted his goal when he became fixated on the infant, perhaps even enjoying the "attention" he received initially from others as a result. Reports of captive apes, including males, becoming fixated on "playthings" or "pets" are not uncommon (6, 7), and it is possible that JM's interest in the infant was initiated by novelty but then waned once the infant became listless and died. In any event, this observation suggests that current proximate explanations for kidnapping should include the possibility that males are motivated by interest in the infant as a "possession" or object of interest, and not solely as a source of meat or means to create a reproductive opportunity.

Research was financed by the NSERC of Canada, The Calgary Zoo and the University of Calgary to HN and by the Australian National University to JM. Thanks to K. Derbyshire for assistance in background research.

References

  1. Hamai M, Nishida T, Takasaki H, Turner L 1992. New records of within-group infanticide and cannibalism in wild chimpanzees. Primates, 33: 151-162.
  2. Collins DA, Busse CD, Goodall J 1984. Infanticide in two populations of savanna baboons. In: Infanticide: Comparative and Evolutionary Perspectives. G. Hausfater and S.B. Hrdy (eds), New York: Aldine Publishing.
  3. Thierry B, Anderson JR 1986. Adoption in anthropoid primates. International Journal of Primatology, 7: 191-216.
  4. Thierry B, Herrenschmidt N 1985. A case of "transient adoption" in a captive group of Tonkean macaques (Macaca tonkeana). Lab. Prim. Newsletter, 24:1-3.
  5. Strum SC 1984. Why males use infants. In: Primate Paternalism, D.M. Taud (ed). Van Nostrand Reinhold: New York.
  6. Patterson F, Linden E 1981. The Education of Koko. Holt, Rinehart and Winston: New York.
  7. Debby Cox, personal communication. Entebbe Wildlife Education Center.

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