Rakali (Water Rat)

Hydromys chrysogaster

Hydromys chrysogaster

The water rat is native to Australia and New Guinea.  It is relatively large, weighing over 600 grams and reaching a length of up to 60cm from nose to tail tip.  The thick soft fur is usually dark brown above and golden-orange below, with a distinctive white tip.  It is well adapted to its semi-aquatic life, possessing webbed feet and water-repellent fur.  Along with the platypus, it is the only Australian amphibious mammal.  Life span is approx. 2 years.

Breeding

Making a nest at the end of a tunnel in the riverbank, breeding can occur throughout the year, with peaks in spring and summer.  As many as five litters, averaging 3-4 young, can be born each year.  Gestation period is 35 days.  The female suckles young for about 4 weeks, which remain with her for another 4 weeks, gradually attaining independence.

Behaviour

The water rat is common in rivers, streams and estuaries throughout the state (fresh or salt).  Although primarily nocturnal, it may be seen during the day.  It has difficulty maintaining its body temperature in cold water, and to restore this, it spends a considerable amount of time shivering on the land, preferably in the sun.

Diet

Unlike most rodents, the water rat is a predator.  Its diet includes aquatic insects, frogs, lizards, fish and crustaceans.

Status

Protected.  Natural predators are snakes and birds of prey.