Living off gum leaves is no easy feat and koalas need a specialised digestive system to do it. They can live off only a few species of Eucalyptus perhaps 10 or 20, of the more than 600 on the continent. Recent reports speak of koalas eating pine needles in a plantation forest. Pine needles, like gum leaves, are hard to digest and contain a range of toxins poisonous to most mammals, but koalas may gain some nourishment from them.