How Do Chimpanzees Hunt and Kill Their Prey?
On The Hunt
It was once thought that chimpanzees were exclusively vegetarian. In the early 1960's, a young Dr. Jane Goodall was the first person to document cooperative hunting among our closest living relatives while working in Gombe, Tanzania. She witnessed these wild apes working together to capture large animals for the consumption of their flesh. Her reports sent shockwaves around the world, and people began to ponder the implications for our own evolution as humans. It was previously believed that we had evolved from exclusively herbivorous, forest-living ancestors and that we became predators once we migrated out into the savanna. However, Dr. Goodall's discovery confirms that both the human and chimpanzee species inherited their diets and hunting tendencies from a common ancestor.
The Victims of Chimpanzee Hunting
Chimpanzees are the only great apes known to engage in organized, communal hunts for larger animals. The creatures they target are usually always mammals. Some of these animals are hunted on the ground whilst others are hunted in the treetops.
Since the very first reports from Gombe, chimpanzee predatory behaviour has been recorded at several other sites across the species' range. These include Tai in the Ivory Coast, Kibale in Uganda and Mahale in Tanzania. The total list of victims stretches to more than 30 different species and includes several types of monkeys, small antelopes (known as duikers), larger antelopes (called bushbucks), flying squirrels and tree pangolins (armoured mammals that look rather like a cross between an anteater and an armadillo).
The most popular prey for chimpanzees at Gombe are red colobus monkeys. These monkeys make up to four-fifths of all their quarry, and of those red colobus caught, about three-quarters are youngsters.
The number of hunts, its participants and their success rates vary across these regions in ways which are not well understood. Seasonal changes and the availability of other foods certainly play a part. Yet, the main hunting peak is in the dry season in Gombe while it is at the start of the rainy season in Mahale. The chimpanzee community's size and its make-up in terms of gender and age also appear to be involved. A predominance of adult and adolescent males in a group usually means that hunts happen more often. Large groups are also more likely to hunt than small ones, as the former contain more potential hunters. Individual personalities also play a role; some large males instigate hunts often while others rarely do so.
In ‘binge’ years hunting becomes far more popular than usual, but again, exactly why this happens is not clear. In a binge year a typical community of 50 to 100 chimpanzees will kill more than 150 victims representing more than 1320 Ibs of dead meat. Yet the annual toll can be fewer than 20 kills for the same group in other years and for other groups regularly.
Who Are the Victims of Chimpanzee Predation?
A Frequent Victim
Chimpanzee Hunting Roles and Strategy
The hunting party varies from a single chimpanzee to a few individuals to even more than 30 at a time. On average, 90% of the hunting parties are male chimpanzees, either full-grown or adolescents. Generally, the more individuals there are in a hunting party, the more successful it is likely to be with success rates in the biggest parties topping 90%. Sometimes, the hunters actively target and chase prey, while in other cases they gather around en masse after happening on a victim by chance.
Division of labor during the hunt itself has been most studied among the Tai chimpanzees. Once the prey is targeted, it appears that some individual chimpanzees act as ‘drivers’ to move it in the desired direction, while others are visible ‘blockers’ cutting off potential escape routes. Along with the drivers and blockers are hidden ‘ambushers’ and ‘captors’ who initiate the kill. The complex coordination of hunting roles takes time to learn. Tai chimpanzees start learning at around the age of 10, and it takes as long as an additional 20 years to become experts.
Chimpanzee Hunting On Film
Sharing The Kill: Social, Political and Sexual Factors
You are probably wondering happens to the hapless colobus monkey and other victims of chimpanzee hunting trips? Usually the prey is torn apart by a chief male (while it is still alive and shrieking) as other excited chimpanzees gather around agitating and begging for a share. Tai chimpanzees are even known to bite and break the prey’s bones in order to extract the nutritious marrow within.
Like the reasons for hunting in the first place, sharing the spoils is a complex business. Generally the dominant males who were most important in the hunt split most of the reward between themselves. But meat from these cooperative kills often represents far more than just food. It also has social, political and sexual overtones. In one group, an alpha male chimpanzee was known to share meat with his allies in the hunting party, presumably to reinforce his status and dominance, while keeping the shares away from his rivals. Another study of a different group showed that hunts were more likely to occur when there were more sexually-receptive females around. Males were more likely to share food with these females if they begged, and the females themselves were more likely to produce babies that survived. In this way, hunting prowess could feed through to reproductive success (for male chimpanzees at least).
Weapon-Wielding Female Chimpanzees
If the original discovery of hunting chimps by Dr. Goodall was shocking enough, a more recent discovery by primatologist Jill Pruetz sent even greater shockwaves around the world and has had even greater implications for our evolution. It appears that humans may have hunted with weapons for far longer than we have previously thought. This is due to the startling discovery by Pruetz of a troop of chimps at Fongoli in Senegal, West Africa, that not only hunt animals, but do so with spears.
Interestingly, it's the females and not the males who hunt in this way. The males tend to rely primarily on their size and great strength to make kills. On the other hand, females are almost always hindered by their children, so they have to be a little more inventive. Their favourite prey are small, furry primates with large eyes called bushbabies. The females, with spears in hand, climb trees seeking out cavities where the nocturnal bushbabies spend the day sleeping. Once a discovery has been made, they simply stab them to death.
Normally, the dominant males will readily steal food from subordinates if they so wish, but things are different at Fongoli. The dominant males actually allow the females and younger males to keep their own kills. Maybe, just maybe, this is a new step in chimpanzee evolution.
Speaking of evolution, the discovery of weapon-wielding female chimpanzees could reveal a few things about our own history. Firstly, its highly likely that a female chimp, rather than a male, invented the first non-human weapon. It could well be that our own hunting methods began the same way—with our ancient female ancestors crafting rudimentary spears while our male ancestors were busy battling for dominance. Maybe the term 'man the hunter', needs to be changed to 'woman the hunter'.
Chimpanzee Hunting On The Web
- BBC - Earth - Chimpanzees over-hunt monkey prey almost to extinction
The apes have killed and eaten so many red colobus monkeys, the population has fallen by 89% and they are having to find new prey
- Hunting - Jane Goodall Institute UK
Founded by renowned primatologist Jane Goodall, the Jane Goodall Institute is a global organisation that empowers people to make a difference for all living things.
© 2018 James Kenny