Long-term home range stability provides foraging benefits in western gorillas

Area of Science:

• Primate behavior and ecology
• Spatial cognition in animals
• Conservation biology

Background:

• Long-term home range stability is thought to enhance fitness through improved foraging and reduced risks.
• Spatial memory is key for primates, but interannual reuse of this knowledge is less studied.
• Western gorillas (Gorilla gorilla) offer a model to investigate site fidelity and its foraging implications.

Purpose of the Study:

• To assess long-term site fidelity in western gorillas.
• To examine the foraging consequences of reusing spatial knowledge over a decade.
• To understand how familiarity with an area impacts foraging efficiency.

Main Methods:

• Analyzed interannual home range overlap over 10 years using grid-based and kernel density methods.
• Monitored a single group of gorillas at the Mondika Research Center.
• Compared foraging (fruit trees, diet diversity) and ranging (daily path length) in familiar vs. unfamiliar areas.

Main Results:

• High average interannual home range overlap was observed throughout the study.
• Home range expansion correlated with increased daily path lengths but not with visiting more fruit trees.
• Reduced familiarity with new areas led to decreased foraging efficiency due to a lack of resource knowledge.

Conclusions:

• Western gorillas at Mondika exhibit significant long-term home range stability.
• This stability likely reflects a strategy leveraging spatial memory for efficient foraging.
• Such a strategy is advantageous given their reliance on unpredictable, ephemeral fruit resources.