Various reactions to dead conspecifics by Mahale chimpanzees have been observed. Reactions were classified into whether the dead conspecific was an infant or adult.
The extreme persistence of one mother who carried her dead infant for about 4 months was noted. Infant-carrying may be prolonged if the dead infants desiccates and becomes mummified, thus clearing the stage of putrefaction. Most mothers may abandon their infants after death due to swarming flies around the corpse and bad smells. Non-mothers generally paid no attention to dead infants but some adult males inspected and tried to snatch them away, possibly motivated by cannibalism. One juvenile female was observed to engage in imaginative play with a mummified infant. An adult female carried and cradled the dried forearm of a red colobus for some days, traveling together with another adult female carrying her mummified infant.
Reactions of chimpanzees to adult conspecific corpses may well be explained in terms of conflicts between approach and avoidance. If approach surpasses avoidance, they will go near bodies and inspect by sniffing, gazing, and sometimes touching. If avoidance surpasses approach, they will climb into nearby trees and rest on branches or day-beds sometimes looking down to see bodies. It has been proposed that vocalizations of wraa calls and huu calls express a combination of emotions such as fear and agitation. Several factors such as state of decomposition and cause of death may increase fear together with curiosity. Females and immatures tended to show more fear than adult males. Some adult males conducted intimidation displays upon encountering dead bodies. They may utilize such unusual situations for bluffing effect. Interestingly, chimpanzees sometimes behave similarly towards the corpses of other mammals. This is noteworthy as non-ape primates such as vervets are reported to pay no attention to ungulates killed by leopards. It is plausible that broad curiosity in chimpanzees is applied to obtaining useful knowledge about their surroundings, such as presence of predators, though their intentions are not so specialized.

View full abstract

We captured 26 males for marking with tattoo using a blowpipe dart containing anesthetic. Individuals shot with a blowpipe got temporarily disabled. When these individuals were released still being disabled, members of the same troop showed various attitudes toward them. Only young males of 5 to 9 years old received aggressive behaviors. Aggressors were also young males of 7 to 8 years old, and they showed both aggressive and affinitive behaviors against the disabled individuals. An adult male and adult females showed only affinitive behaviors, and they protected the disabled individuals from the attack by young males. Close and unstable dominance relationships might cause the aggressive interactions between young males.

View full abstract

To grasp distribution of wild Japanese macaques in Wakayama Prefecture, we tried a method of witness report by local people in a village. The study site was Nakatsu Village in Wakayama Prefecture, where actual damages to crops by wild Japanese macaques had been reported. We interviewed local people who engaged in agriculture and asked to report appearance of Japanese macaques during a month by filling a form. Forty seven forms were distributed and 29 of them returned, and 48 cases of witness were obtained. We estimated the distribution of Japanese macaque troops in this village by using those reports and the results of interview. The degree of precision of this witness report is not clear and further intensive studies are necessary to apply this method to broader area.

View full abstract