Australia is of course well known for it’s variety of unusual animals. Since it is a very sparsely populated continent, these animals roam wild in the bush. Which means that they can wander onto the highway and have an unexpected meeting with a fast moving vehicle.
The highway department provides these helpful signs, I suppose, so that you know what it was that you crushed as you cruised along at 110 kilometers/hour (the usual limit on country roads). It is not uncommon to see one of these poor creatures in it’s final repose along the side of the road. Identifying just what animal it was, is another story.
Of course colliding with any of the larger Australian fauna can also be quite dangerous to the car and driver, so caution is advisable.