Social Spacing
Photo Courtesy of Dr. Pascal Ngoboka from Ngamba Chimp Sanctuary, Lake Victoria, Uganda
Home Range
Each chimpanzee community inhabits a particular home range, or area of land within which they will travel, forage and scavange, and sleep. Home ranges do not have clear boundaries and often overlap between neighboring communities (Goodall, 1986).
Chimpanzees travel about their home range during the day mostly on ground. At night they will build nests in trees at whichever spot they choose to stop for the day's end. Nest building requires a great deal of manipulation and cognitive ability. Chimpanzees build their nests in trees and will improve the comfort level by adding soft twigs and leaves. Nests may vary structurally across different chimpanzee populations, but such variation seems to be due to environmental factors such as predator pressure and available resources. Nests consist of a foundation, a central mattress, and a lining made of leaves and twigs. The height of the nest off of the ground is variable, as much as 3 to 45 meters. Chimpanzees will build both day and night nests, as they spend at least half of their lives within nests. Though new nests are built almost every day and night, the site selection process is usually very particular (Fruth and Hohmann, 1994).
Photo Courtesy of Jane Goodall Institute
Classical Territories
Within their home ranges, male chimpanzees will often defend a certain core area, which serves as their classical territory. Specific ecological pressures, such as feeding, may be responsible for differences in their social organization that lead to a need for such territories. Specifically, food choice and distribution are important components of developing primate social behavior in general. For example, dominance level has a greater impact on obtaining food when the food is distributed in definite clumps rather than evenly spread out over the area. For chimpanzees, intragroup feeding competition may be the most important factor leading to their flexible party composition of a fission-fusion system within a territory. They tend to feed on small, high-quality food patches that are irregularly dispersed in their environment (Brent, et al., 1993).
Territorial Defense
Community members will travel to the periphery of their home ranges for the following reasons: 1. a consortship has been formed and the male leads the female to a place where they are less likely to be bothered by other chimpanzees, 2. an abundant food source is located in the periphery and a group makes an excursion to this spot to feed, 3. males patrol or monitor the periphery, sometimes accompanied by females in estrus. Patrols may be made if a group feeding is going on at the periphery and the males are aware that neighboring chimpanzees may be nearby. They will patrol by carefully and silently traveling in a small, dense group. They will often pause to listen carefully for any sounds or hint of neighboring chimps. Sometimes they will climb in trees to stop and listen. They may also sniff the ground and even pick up leaves, feces, or discarded food or tools to smell. If a sleeping nest is spotted that appears relatively freshly made, they will inspect it carefully and then destroy it. Their silence is especially remarkable during this time, and they will take careful measures not to walk on dry leaves or make any vocal noises. If neighboring chimpanzees are spotted, as they often are, responses depend on the size and number of the two parties. In some cases the patrolling chimpanzees will quietly avoid confrontation, but during other times they will aggressively chase or fight the neighbors (Goodall, 1986).