Chimpanzees As Neighbors

Chimpanzees and humans both live in communities but these communities can be very different from each other.

 

Chimpanzee communities can consist of about 20-100 chimps whereas human communities can be found in the millions, but each human and chimpanzee community may have smaller groups. Chimpanzee groups live in selected territories, similar to humans who live in different communities in different countries. Think about it like this: if you live in New York State, you could say you live in the group called New York but you are part of the larger community and territory of the United States. However, chimpanzee’s territories are much smaller than ours; only consisting of 30-150 square miles. That is as big as 50-250 football fields! Territories consist of two different areas: the border and the core.  A border or peripheral area of a territory is the outside area of the community. The core area of a territory  is in the middle of the territory and is the most heavily used portion of the territory.

The main factors which affect a chimpanzee’s territory size are food availability and intercommunity relations. Chimpanzees are a very social species within their communities. It is important for communities to have strong social bonds with each other to ensure their welfare. However, such hospitality does not usually extend to neighboring communities. Chimpanzees are very territorial and protective. Males and sometimes females and juveniles go on 'patrols' to ensure other chimpanzees do not enter their territory. These patrols are usually a single line of chimpanzees that walk along their territory’s border. These patrols are similar to a  community watch in humans, where people keep an eye out for each other to make sure there are no intruders that can harm them walking around their neighborhood. There are some differences between human societies and chimp societies. When human communities are threatened we call the cops; chimpanzees on the other hand will attack the intruder if the situation calls for such action. If the patrollers are too few in number they will retreat back to their core territory, but if they outnumber the intruders a fight usually is started. The fight ends when the intruders leave. If the intruders don’t leave then a war may be started between two communities. When a community wins a war they receive similar rewards that early humans received when they went to war. The victors gain land and territory, new food sources, and other resources. The victors also get improved security and strength by adding numbers to their group.  The addition of more females leads to more chimpanzees in the community and more genetic diversity. Besides all of these benefits new research shows that when there is more territory, females become bigger and have a more births, thus increasing population by decreasing the time it takes to produce offspring.

 

There are differences in chimpanzee communities between who can immigrate and who cannot and how a new chimp is accepted into a new community. Males do not immigrate because males don’t allow males from other communities to join their troupe. If a new male tries to join a troupe he will be fought off. So, males typically remain in their original group, however females leave their communities at adolescence, which is around 9-14 years old. When a new female enters a community they are generally accepted by males but resident females are not as happy with the new female. A female that is old enough to have a baby will be welcomed and protected by the males, but the other females of the group may try and attack her. These females want to protect their status  because the younger immigrant females could outrank them and end up getting more food and better nesting sites. It has been speculated that females leave the community because of negative social developments and availability of energy for dispersal, not in search of mates. Regardless of why the female leaves, it is in fact a good thing for her that she does. When she leaves she increases genetic diversity of wild chimps.

 

 

Message from CAC'ers

 

We hiked for miles and miles within the territory of only one community of chimpanzees just to see some of them. This long hike showed us just how big their range really was. Later on, after all that hiking, when we returned to camp we saw the same chimpanzees miles from when we first spotted them!

 

 

Content provided by Canisius College students under the direction of Michael Noonan, PhD.