Rattus rattus

Black Rat at Tathra Public School

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Identification history

Rattus rattus

8 Jun 2020

AndrewMcCutcheon

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User's notes

Repeatedly appeared until 2.45 AM in front of the same motion sensing camera that recorded the Dusky Antechinus in the gully at the edge of Davidson St, Tathra.

5 comments

JackieMiles wrote:

9 Jun 2020

A look at the relative tail and body length would have been nice, but those ears look very long, like they would come to the front of the eye if pressed forward, so I'm happy with R. rattus and not R. fuscipes.

AndrewMcCutcheon wrote:

9 Jun 2020

Jackie, I have added another image showing more of the tail/body length ratio, which is not complete but the best I have with this set of images. In this instance the problem for photographing larger animals is that the focal point has been brought much closer to the camera by placing a cut piece of a +2 reading glass lens over the camera lens. I do this for taking small dasyurids and native rodents to get a larger image of and improve the definition of these small mammals, to enable more accurate ID. While the rat was too large to get the whole animal into the image, it does show more clearly another diagnostic feature of R. rattus; the long guard hairs over the shorter and softer fur underneath. This is not so well defined with R. fuscipes.

JackieMiles wrote:

9 Jun 2020

OK, I like the way you'd drawn in the rest of the nose and tail, so I could see the tail was slightly longer than head-body. Blimey, you reckon the long guard hairs are more a R. rattus feature than fuscipes do you? I thought it was the other way round, based on various photos we've taken over the years. Do you want to look at the R. fuscipes sightings (go to species, find rats, click on Rattus fuscipes and it'll show you all the sightings so far)? Paul put in 3 from Wonboyn that I thought were fuscipes but they have quite marked long guard hairs. Add a comment on each of those sightings if you think I got the ID wrong, or even if it looks right. I'm no expert on mammals really, just got the books. Been a hell of a long time since I've had any of these things in the hand (other than Rattus rattus which we trap on the verandah pretty regularly at this time of year, but haven't so far this year).

AndrewMcCutcheon wrote:

9 Jun 2020

That is a remarkably interesting individual Paul trapped at Wonboyn, and I would have to say I have never seen any Bush Rats quite like it. As there are only two species of Rattus this animal could possibly be (not including the more distinct R. lutreolus) for that location I think your ID is correct. The young Bush Rat Paul also found at Wonboyn in January 2018 and another submitted by John Tann from Bermagui have fur more like those I am familiar with in Victoria. I am getting a strong impression that R. fuscipes is a highly variable species in appearance and given its variability, long stiff guard hairs contrasting with soft fur underneath is not a guide. I have seen another R. fuscipes subspecies (coracius) in North Queensland, which looks so different I thought it was another species until I was told by a local expert that they were Bush Rats. In the future I will stick with ear size and tail length for positive ID between these two species of Rattus. I will look over some of my motion sensing camera images taken in the NSW south coast region again to make sure I have a few Rattus sp. correctly identified.

JackieMiles wrote:

10 Jun 2020

Thanks Andrew. Maybe the taxonomists need to have another go at the rats, though I'd be the last person to encourage it - they are hard enough to tell apart now, without further splitting.

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