Dietary Variability Among Mountain Gorilla Groups Across Volcanoes National Park, Rwanda

Area of Science:

• Primate ecology
• Conservation biology
• Nutritional ecology

Background:

• Endangered mountain gorillas inhabit complex forest ecosystems in Volcanoes National Park (VNP), Rwanda.
• Studies show differing habitat use and population growth rates between high-elevation southwest and lower-elevation northeast VNP regions.
• Understanding dietary variability is crucial for discerning distribution, population trends, and conservation needs.

Purpose of the Study:

• To assess dietary variability and compare nutritional components of key mountain gorilla foods across VNP regions.
• To investigate if diet quality differences correlate with observed within-population growth variations.
• To inform conservation management through habitat suitability assessments.

Main Methods:

• Integrated feeding and ranging data from November 2019 to December 2022.
• Collected and analyzed nutritional components of key food plants (approx. 80% of diet).
• Compared newly collected and previously assessed food plant samples using standardized methods.

Main Results:

• Recorded 57 new food items for the study population.
• Observed distinct vegetation zone use and high dietary variability with low diet overlap between southwest and northeast VNP groups.
• Key foods in the northeast, despite a more diverse diet, had comparable nutrient concentrations to those in the southwest.

Conclusions:

• Diet quality is unlikely to be the primary driver of heterogeneous population growth rates in mountain gorillas within VNP.
• Further research should explore factors like food distribution, biomass, and energy expenditure.
• Findings contribute essential data for mountain gorilla habitat suitability assessments and conservation strategies.