Sorry to be the bearer of bad tidings. The easiest way to tell a Black Rat from an antechinus is that the tail of the rat is much longer than the rest of the body while with the Antechinus the tails is about the length of the rest of the body.
Hi enjayjay, Black Rats are probably visiting most back yards, especially ones with chooks. People are usually unaware of them. So no need to put baits out just because of this photo. But if you do need to control rats in a veggie garden, and possums too maybe, you would generally be a lot more effective to instal a physical barrier, than to try killing rats year after year. And we have become increasingly aware that the commonest agents in rat baits are killing owls when the owls catch the slow rats.