They are there to advise you of known 'hot spots'. Animals react differently to approaching cars and it is best to let the animal move off first before passing. Possums are territorial, if one adopts the nest box it is likely to keep others away from your roof and garden. If you are lucky enough to live in close proximity to wild koala populations, it is important to remember that you are sharing the koalas' territory and that you can easily threaten their survival without meaning to. Keep your dogs tied up, preferably inside, at night.
Dogs kill koalas.
Hundreds of koalas are killed by dogs each year and even if your dog is within your property boundary, it may still kill a koala. This is not the dog's fault but it is your responsibility if you live in a koala area. Cover the name and address with a plain sticker or glue on a square of paper. Recycle all paper that can't be re-used. The back of a used envelope makes an ideal shopping list.