From a good feed the koala should get around 6 hours of energy out of a 24 hour period. This time is used carefully. They do move around in the day time in search of food or a good shade tree. During a bush fire the koalas will remain in the fork of trees. They have also been seen covering the ground at some reasonable speeds to escape.
Koalas are also excellent swimmers and so can cross creeks.
Their lives are solitary and contact with other koalas occurs only during mating, care of young and defence of territory. Males are especially territorial during the breeding season. They mark trees with scent from the gland on their chest. They also defend their territory from other males by making loud gutteral grunting sounds. The females have a high pitched scream.