#1Thanks for posting. This is a hard brief and I think you've done well with mixing the environmental and feral animal components. I think these colours and contrast might disappear on a page a bit (?) Would it work if it was like a hot iron brand - or the stencil across a sack of wool or coffee for export?
#3 I do like the feel, but I think the bite mark is a bit too abstract (took me a second to figure it out) and the wattle is not obviously wattle, but more tropical looking. Wattle can become a significant weed itself, so I'm not sure that it is a good symbol for us.
babo - could the first one be changed to the same design with a simple map of Australia instead of the tree? With sharper claw marks, it might worjk really well. My wife ranks you first!
#37 looks a bit too much like a logo for the State of Queensland that has rays of sunshine coming out of the state - high recognition here. I don't like #39 so much - it might offend some people, or at least confuse them #38 might work if the "scratches" were sharper and more clearly claw marks. They are impressive.
#69 Alternative for web use only #70 Shield/buckler concept (protecting environment etc) forgot to try this one in flat colour so not sure if it'll work.