Primatology.net

Also in the latest Current Biology and first shared by John Hawks is news that may shakeup what you understood was unique to bonobo behavior, that they didn’t hunt other primates. We know that some bonobos eat rodents and small antelopes, albeit infrequently, but for quite sometime we assumed they didn’t consume other primates because they seemed to be placid maternally structured social beings.

The title of the new paper spills all the beans, “Primate hunting by bonobos at LuiKotale, Salonga National Park.” As I just mentioned, bonobos have been popularized by many to be a peace loving species, particularly because of the lack of male dominated social system and far less documented occurrences of physical violence. Such observations have often been used to explain the relative absence of hunting and meat eating in bonobos. In the words of New Yorker writer Ian Parker, bonobos are [were],

“equal parts dolphin, Dalai Lama, and Warren Beatty,”

But earlier this year we got a glimpse into the more devious carnivorous behavior of bonobos, when one of the co-authors of the current paper, Gottfried Hohmann, and another research published in Folia Primatologica, “New Records on Prey Capture and Meat Eating by Bonobos at Lui Kotale, Salonga National Park, Democratic Republic of Congo,” their observations of the presence of monkey finger bones in bonobo fecal samples. In the new Current Biology paper Hohmann and Martin Surbeck publish their observations of bonobos hunting diurnal, arboreal and group living primates at LuiKotale in the Salonga National Park, Democratic Republic of Congo.

The following table from the paper summarizes their observations:

Table 1: Bonobo Monkey Hunts at LuiKotale

The results show us that there were 5 attempts, and 2 of the 3 successful hunts were made by females. Among chimpanzees, females have been rarely been seen taking an active part in hunting parties. But these two female bonobos rocketed up into the trees and attacked their monkey prey just as effectively as the males. I share Frans de Waal‘s opinion that this study is a milestone piece and changes our very foundation of bonobo social organization and socio-ecology.

But hunting may not be a ubiquitous behavior among all bonobos. As Hawks points out,

“at other field sites the bonobos interact in different ways with monkey species, ranging to mutual grooming.”

In fact, bonobos have been observed playing with baby black-and-white colobus monkeys and been seen engaging in grooming behavior with red colobus monkeys, much like adult chimpanzees hunting baboon babies that their offspring were playing with just days earlier. Bipolar anyone?

Surbeck M, Hohmann G. 2008. Primate hunting by bonobos at LuiKotale, Salonga National Park. Current Biology 18, R906-R907. DOI:10.1016/j.cub.2008.08.040

From John Hawks comes distressing news of a 90% decline in headcount of chimpanzees from Côte d’Ivoire, published in the latest issue of Current Biology. The paper, “Alarming decline of West African chimpanzees in Côte d’Ivoire,” is authored by some familiar names. One that I quickly recognized is Christophe Boesche, who captured videos of chimpanzee nut cracking behavior.

West African Chimpanzees

The team conducted a survey of the chimpanzees and found only 800 to 1,200 individuals, which is a significant drop from the down 8,000 to 12,000 individuals counted in 1989-90. The drop in chimpanzees correlates Côte d’Ivoire’s 50% growth human population sizes. With the increased human footprint comes more hunting and deforestation, driving chimpanzee populations down.

In 8 of the 11 survey sites, researchers found significantly fewer chimp nests than had been found in 1989-90. In Marahoué National Park, study co-author Campbell found only one nest, versus 234 in 1989-90.  The only site that did not experience a decline in population is the Taï National Park, a UNESCO World Heritage site that has benefited from intensive research and conservation efforts. The Taï numbers suggest that the apes’ numbers respond to stable conservation efforts.

Our collective knowledge of west African chimps is far less than the east African chimp populations. With recent findings, like the 4,300 years of continuous nut cracking behavior among these populations, we’ve only begun to understand the depth of their behaviors and abilities.

Campbell G, Kuehl H, Kouamé PN, Boesch C. 2008. Alarming decline of West African chimpanzees in Côte d’Ivoire. Current Biology 18, R903-R904. DOI:10.1016/j.cub.2008.08.015