Richard Wrangham discusses apparent doll play by young chimpanzees. See the striking footage from Kanyawara on BBC Earth.
By Drew Enigk and Kris Sabbi
Chimpanzees occasionally supplement their diet of fruit and herbaceous vegetation with meat, which they most frequently obtain by hunting red colobus monkeys. Rates of hunting and successful capture of prey vary across communities. For example, within Kibale National Park, chimpanzees in the Ngogo community have decimated local red colobus populations, while chimpanzees in Kanyawara have typically hunted less often. Since Eslom took over the alpha position in January, however, the Kanyawara chimpanzees have targeted monkeys more frequently, and caught many more per hunt.
Eslom instigates a large fraction of hunts in Kanyawara, taking after his father, Johnny, who was one of the community’s most active hunters before his death in 2014. A newly published study by Ian Gilby and colleagues uses over 70 years of collective behavioral data from three study sites, including Kanyawara, to examine the effects of “impact hunters” like Johnny on community hunting rates. The impact hunter hypothesis proposes that certain individuals hunt more readily than others, and that by seizing the initiative during encounters, they cause monkeys to scatter, creating opportunities for others to catch prey. The presence of impact hunters during monkey encounters is positively associated with the probability of a hunt occurring.
Several of the hunts in which Eslom was involved after his alpha takeover in early 2015 yielded more than five red colobus captures, with Eslom sometimes responsible for >50% of the kills. This trend continued into the summer. In early June, Eslom single-handedly captured a grey-cheeked mangabey and two black-and-white colobus monkeys. On June 24, the Kanyawara chimpanzees took down a record number of colobus in a single hunt!
Before the chaos started, the chimpanzees were lounging and playing on a hillside. Suddenly, chimpanzee hunting calls cut through the air, indicating that monkeys had been spotted and targeted. Suddenly, everyone was at full attention, sprinting toward the call.
Eslom was already up a tree beside Kanyawara’s second-best hunter, an adolescent male named Tuber. Other males displayed beneath them, dragging branches as they ran from one side of the group to the other. While female and juvenile monkeys retreated to the top of the tree, the male colobus formed a defensive line beneath them, squawking and screaming at their enemies below. Eslom and Tuber individually rushed at the monkeys, but each was forced back. More and more chimpanzees joined the offensive. With each attack, the colobus banded together, repelling one chimp at a time. Finally, a hole opened up in the monkeys’ defenses, and the chimpanzees rushed in toward the females.
The pace of the hunt escalated quickly, with panicked monkeys scattering from their perches. Soon they misjudged their leaps, falling from thin branches into the eager hands of the chimpanzees. They were seized so quickly that we researchers could barely keep up with the action.
Our voices rang out across the scene: “Eslom caught one!” “Tuke—Tuke has one!” “—And Tuber!” “Tacugama!!” Four males, four monkeys. By the fifth kill, even the young chimpanzees were catching monkeys! Adult males are the usual hunters among chimpanzees, so it was especially surprising that three of the kills were made by 6-11 year-olds, and that two of these young hunters were females. When the slaughter was over, nine red colobus lay dead, the most successful hunt ever recorded at Kanyawara, and particularly noteworthy considering the involvement of the young chimpanzees. (The record from Ngogo, with many more males hunting, is 13.)
Eslom killed two monkeys in this historic hunt, and a large party of chimpanzees spent the rest of the day sharing the spoils. Now that Eslom has attained alpha status and entered his early 20s – prime hunting years for male chimpanzees – he appears to have established himself as the new impact hunter at Kanyawara.
The Kibale Chimpanzee Project (https://kibalechimpanzees.wordpress.com) seeks a postdoctoral scholar, based at the Department of Anthropology at the University of New Mexico, to participate in an NIH-funded study of aging in wild chimpanzees. This project involves the development and application of non-invasive methods to study health and aging in wild chimpanzees in the Kibale National Park, Uganda. The successful applicant will coordinate activities in the endocrinology laboratory, organize incoming data, conduct visits to the field site, and work with PIs Melissa Emery Thompson and Martin Muller to analyze and publish findings. The scholar will be encouraged to develop their own research interests relevant to the broader aims of the project, and this may incorporate primary field work. This is a one-year position, renewable for at least one additional year pending renewal of funding and satisfactory performance. We seek a self-motivated candidate that can work independently but also function well as a member of a team.
Required qualifications: Ph.D. in anthropology, biology, ecology, zoology, or other related field by the time of position start date; experience with observational research methods; evidence of competence in statistics.
Preferred qualifications: expertise in executing laboratory protocols (hormonal or other); previous experience with primates, humans, or other social species; ability to travel internationally and function in field conditions; competency with Microsoft Access; excellent verbal and written communication skills.
The position is funded at $45,000 plus benefits; additional funding will be provided for research costs (travel, research fees, etc.).
Applications received by December 15, 2015, will receive best consideration. Anticipated start date for the position is March 1, 2016. Please send a CV, cover letter outlining your relevant experience and research interests, 1-2 professional writing samples, and the names of 2 recommenders to Melissa Emery Thompson (email@example.com).
Since 1997, KCP has collaborated with the Uganda Wildlife Authority to remove wire snares set by poachers in the forest. This work has just been featured in The Guardian, with photos from Ronan Donovan and others:
KCP Field Manager Dr. Emily Otali has just been featured on BBC Radio. Listen to her discuss her work with the Kibale Chimpanzee Project here:
GRASP (Great Apes Survival Partnership) just released this short video, which will be shown to the UN General Assembly today in honor of World Wildlife Day. Narrated by KCP co-director Dr. Richard Wrangham, it explains some of the threats facing wild apes. (Warning: Contains graphic images of ape bushmeat.)