The mammal diversity is not the only feature; the vegetation and ruggedness of the Georges River Gorge, of course, are superb and much more accessible than the mammals.

Then there are the birds which are many and varied and which often visit our suburban backyards.

Pam Hindes, whose home adjoins Spring Creek, shares her garden with a Satin bower bird and its bower and has the pleasure of watching the deep blue-coloured male performing in the bower. Even though I live three kilometres from the bush, bower birds occasionally visit but none has found our garden suitable for constructing a bower.

To my great delight this week, however, we were visited by three Gang-gang cockatoos, two of which had the distinctive red head and wispy crest of the mature male. These quaint grey parrots, with their wheezy rattle of a call are remarkably tolerant of humans and my visitors didn't fly away as I approached with my camera.

Usually in December they would nest in tree hollows of tall mountain forests. They usually visit drier, lower woodlands in winter so I hope nothing is amiss. Their conservation status in NSW is "vulnerable".

Other unusual visitors to my garden this week were a King parrot and a trio of Channel-billed cuckoos. The former, also red-headed in the male but with a green body, is usually found in rainforests or wet sclerophyll forests. The latter are very large cuckoos with massive bills and a raucous call that sounds like a kookaburra's introductory notes.

Unfortunately they sometimes call all night! They've just arrived from New Guinea to where they'll return in March after laying their eggs in magpies' and currawongs' nests.

■On the koala front we've had another sighting in O'Hares Road by the Lynwood Park Rural Fire Service volunteer and a sighting of our recently radio-collared Heather who has moved from Georges River Road down to Peter Meadows Creek and is now back in a garden beside Georges River Road, a journey of 2 kilometres as the crow flies.

Report koala sightings on the UWS pager, 9962 9996.