16/03/2017
Koalas are Foragers.
Koalas are herbivorous, and while most of their diet consists of eucalypt leaves, they can be found in trees of other genera, such as Acacia, Allocasuarina, Callitris, Leptospermum, and Melaleuca. Although the foliage of over 600 species of Eucalyptus is available, the koala shows a strong preference for around 30. They tend to choose species that have a high protein content and low proportions of fibre and lignin. The most favoured species are Eucalyptus microcorys, E. tereticornis, and E. camaldulensis, which, on average, make up more than 20% of their diet. Despite its reputation as a fussy eater, the koala is more generalist than some other marsupial species, such as the greater glider. Since eucalypt leaves have a high water content, the koala does not need to drink often; its daily water turnover rate ranges from 71 to 91 ml/kg of body weight. Although females can meet their water requirements from eating leaves, larger males require additional water found on the ground or in tree hollows. When feeding, a koala holds onto a branch with hindpaws and one forepaw while the other forepaw grasps foliage. Small koalas can move close to the end of a branch, but larger ones stay near the thicker bases. Koalas consume up to 400 grams (14 oz) of leaves a day, spread over four to six feeding sessions. Despite their adaptations to a low-energy lifestyle, they have meager fat reserves and need to feed often.
Because they get so little energy from their diet, koalas must limit their energy use and sleep 20 hours a day; only 4 hours a day are spent in active movement. They are predominantly active at night and spend most of their waking hours feeding. They typically eat and sleep in the same tree, possibly for as long as a day. On very hot days, a koala may climb down to the coolest part of the tree which is cooler than the surrounding air. The koala hugs the tree to lose heat without panting. On warm days, a koala may rest with its back against a branch or lie on its stomach or back with its limbs dangling. During cold, wet periods, it curls itself into a tight ball to conserve energy. On windy days, a koala finds a lower, thicker branch on which to rest. While it spends most of the time in the tree, the animal descends to the ground to move to another tree, walking on all fours. The koala usually grooms itself with its hindpaws, but sometimes uses its forepaws or mouth.
