The main diet of koalas consists predominantly of eucalyptus leaves. Koalas are herbivorous marsupials native to Australia, and they have a specialized digestive system to process the tough, fibrous leaves of eucalyptus trees. Eucalyptus leaves are low in nutrients and high in fiber, which is why koalas consume large quantities—about 1 to 2 kilograms per day—to meet their energy needs. They are selective feeders, favoring certain eucalyptus species while avoiding others due to toxicity levels or nutrient content. This specialized diet contributes to their unique ecological niche within their habitat.