ZooNooz Article - march 2004

Things that go bump in the night

Is that scratching in the roof a feral mouse or a harmless native antechinus? And what is it that has been digging holes in the vegetable patch? WENDY GLEEN presents a guide to some of the small native mammals that could be mistaken for feral rodents, and explains how you can tell them apart.

Photographs Jo Nevin
Illustrations Katerina Sakkas

Feathertail Glider

Much as we may curse those early morning roof-stomping sessions courtesy of the local possum clan, or the raucous dawn chorus from parrots and lorikeets, these animals bring life, movement and colour to our suburbs, and our lives would be immeasurably poorer without them.

But while parrots and possums make their presence very obvious, the majority of native mammals live a shy, secretive existence, often undetected on our very doorsteps.

The small creature that scampers and rustles around the house at night (especially if you're lucky enough to live near bushland) can be quite tricky to identify. Telling a feral rat from a harmless native mammal is not always easy, and you have to become a bit of a detective, putting all the clues together and often concluding the case on circumstantial evidence.

To confuse the issue, there are two species of introduced (feral) rodents likely to be found around human habitation - the Rat (Black and Brown), and the House Mouse. These species can cause damage to human dwellings and food stores, and can become a serious pest if their numbers explode.

Unfortunately, if you live in the suburbs with no or little native vegetation, any small mammal visitor is almost certain to be a feral rodent. People are often convinced that their visitor is not a rat as the behaviour is not rat-like, or the animal looks too cute. But be warned - these canny 'ferals' are experts of disguise. They can exhibit a wide range of often quite extraordinary behaviours, and are also masters of the 'cute act'.

FERAL RODENTS

Black Rat photograph courtesy London Zoo

The most conclusive characteristic of these is their smell! Sniff where they've been seen lurking or nesting. Black and Brown Rats have a very distinctive 'ratty' smell, and the House Mouse has a 'mousey' odour. The natives either have virtually no smell, or a very different scent.

Brown Rat

Despite the name, these can come in many different colours, with the tail usually about the length of the head and body combined. Laboratory or pet rats are a strain of this species. These animals tend to be very aggressive if trapped.

House Mouse

If you find a dead one, use a magnifying glass to check its top incisors. If there is a tiny notch, then it is a House Mouse, not a native rodent. Otherwise, go by smell.

NATIVE MAMMALS

Bush and Swamp Rats (native rodents) These are true rodents, like the introduced species, but are native to Australia and have very different lifestyles. They do not usually inhabit human dwellings as they are very shy.

The tails of native rodents tend to look as though they've been added on to the end of the body, whereas a feral rodent's tail tends to taper from the end of the body (have a look at the native rodents in Taronga's Nocturnal House).

You can tell a Bush Rat from a Swamp Rat because the soles of its hind feet are paler. They also have a strange smell, almost like barbecue smoke.

Antechinus

Antechinus

These are mouse-sized, insectivorous/carnivorous marsupials, related to quolls and Tasmanian Devils. They have rows of needle-like teeth and a flatter, pointier snout, so are easy to distinguish from mice if you are able to get a close look. They will also eat fruit and cereals.

Bandicoots

Long-nosed Bandicoot

These are marsupials, related to Bilbies, and are quite well known around the northern Sydney suburbs. You can often see the tell-tale conical holes in the ground where they have been digging in search of food. Their tails are much shorter than a rat's, and their snouts are longer and pointed. If startled, they emit a funny 'honking' sound, rather like a bicycle horn. Their size can be extremely variable.

Feathertail Glider

This is another marsupial, about the size of a mouse. Gliders often nest in groups and sometimes turn up in electrical junction boxes. They are easy to identify by their feather-like tail.

Eastern Pygmy-possum

Eastern Pygmy-possum

These very cute mouse-sized marsupials have long prehensile tails which they use for climbing. They are agile and arboreal. If they are dormant (a bit like hibernation) they will not necessarily wake when disturbed but will roll into your hands with the tail neatly curled up and the ears folded snugly against the head.

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