Vic, you seem to be under the impression that koalas don't drink water?

They do, and will actively seek out water in particularly hot weather or, as Wilk said, when the trees are sufferning from lack of water.

The drought around here was quite bad last summer. The trees become stressed. The gums are drought tolerant but they protect themsleves and their becomes dry and have even less nutritional value than normal. The koalas starve, even though it looks like they have plenty of food.

I agree with removing them from KI. Crimson rosellas were introduced to Norfolk Is. Pretty bird but they have taken over the nesting sites of the native parrot which is now nearly extinct. They are trying to eradicate the rosellas now, as they should.