Thanks heaps. And for the swift response. The one in the photo was released yesterday. I have another caught last night and it will also now get released.
You have three possible Rattus species: introduced R. rattus (Black/Roof/Ship Rat); native R. fuscipes (Bush Rat); and native R. lutreolus (Swamp Rat). Dentition is the definitive thing and dimensions from dead specimens, or DNA, so to ID rodents from images is not easy. Rattus rattus has a tail length longer than its head-body length, and ears that reach past the first 1/3 of the eye when pressed forward with a finger. R. rattus ears are longer than R fuscipes which are longer than R lutreolus. R. lutreolus has grey fur. Bush rats are variable but the longer dark guard hairs are a feature. Head shape is different in mature R rattus but hard to define. Number of teats can help. Pads under the hindfoot often differ, also the colour of the upper surface of the hind feet. Juvenile R rattus look a bit like everything else. Some people can separate the ID of the juveniles but I can't do it.
Thanks for that. We have no trouble identifying the black rats which are what we catch the most often and actually what we set the traps for since they are introduced and not appropriate in this environment (like foxes and pigs and rabbits which we also remove when possible). And yes we use tail length and ears as the identifier. It isn't R. lutreolus either (tail length seems a giveaway on that). Which leaves the bush rat. Someone mentioned brown rats to me which is why I asked. I didn't think they were found outside city areas. These are actually the first live bush rats I have seen here. I found one dead one a few years ago.