if it's of any interest, sittella means "little nuthatch" (from the nuthatch genus Sitta) because they lead a similar lifestyle creeping around on tree-trunks.
Cheers for that. I had posted a nuthatch pic from Mongolia for identification a few months ago and this Aussie bird reminded me of that one.
So I have been reading the Pizzey & Knight Australian bird field guide, and it says (in the section about using bird habits as ID tools) that you can tell sittellas from treecreepers by their movements on tree trunks - the creepers work their way up from the base, sittellas start at the top. Pretty cool thing to know I reckon. I hope I get to see these birds soon.