Gorillas are large, primarily herbivorous great apes found in the tropical forests of equatorial Africa. Their diet consists almost entirely of plant-based foods, as they are adapted to thrive on vegetation. This dietary classification is consistent across both eastern and western gorilla species.
What Gorillas Primarily Eat
Gorillas primarily consume plant matter, with their diet varying by species and seasonal availability. Mountain gorillas eat fibrous vegetation like leaves, stems, bamboo shoots, thistles, and nettles. Over 85% of their diet includes leaves, shoots, and stems from more than 140 plant species. Western lowland gorillas, found in different forest environments, supplement their diet with more fruit when available.
Gorillas are selective foragers, eating specific parts of plants like leaves, pith, stalks, or roots. An adult male gorilla can consume around 40 pounds (18 kilograms) of fruits and vegetables daily to meet nutritional needs. Because plant material has a lower caloric density compared to meat, gorillas must consume large quantities to gain sufficient energy. During dry seasons, when fruit is scarce, western gorillas rely more on fibrous plants and tree bark for sustenance.
The Rare Cases of Animal Protein
Gorillas occasionally ingest small amounts of animal protein, primarily insects. This is typically accidental, occurring during foraging. Termites, ants, snails, and caterpillars might be consumed opportunistically. This incidental intake constitutes a very small fraction of their overall diet, often less than 1% or 2%.
Gorillas do not actively hunt other vertebrates for food. The protein from insects contributes negligibly to their total nutritional requirements. Such instances supplement their plant-based diet, rather than being an intentional pursuit of animal flesh. Reports of gorillas consuming larger animals are rare and generally lack scientific documentation.
Why Gorillas Are Herbivores
Gorillas have specialized adaptations for a plant-based diet. Their digestive systems are designed to process tough, fibrous vegetation through fermentation. This includes a large gut and a long digestive tract, which allow for the efficient breakdown of plant fibers to extract nutrients.
Their dentition further supports their herbivorous lifestyle. Gorillas have large, powerful molars and premolars that are well-suited for grinding and crushing plant matter. While adult male gorillas have prominent canines, these are primarily used for display and defense against competing males, not for tearing meat. The relatively weaker stomach acid of gorillas, with a pH between 5 and 7, is also indicative of a plant-based diet, differing significantly from the highly acidic stomachs of carnivores.
Ecological Significance of Their Diet
The dietary habits of gorillas play a significant role in shaping their forest ecosystems. As they consume large quantities of fruit, they become effective seed dispersers. Seeds pass through their digestive system intact and are deposited in new locations through their faeces, contributing to forest regeneration and plant diversity. Over half of the seeds gorillas disperse are deposited at their nesting sites, which are often in areas with open canopy, allowing the seeds to benefit from available light.
Gorilla foraging activities also influence plant growth and habitat structure. By moving through the forest and consuming vegetation, they create small clearings, allowing sunlight to reach the forest floor and promoting the growth of new plants. Their droppings also return nutrients to the soil, supporting further plant growth. This continuous interaction between gorillas and their plant food sources helps maintain the health and biodiversity of their forest habitats.