Hydromys chrysogaster
is not an ordinary rat. It has evolved certain features for its
survival in its environment such as a flattened, fury tail and
webbed hind-feet. Appart from the platypus, it is the only
Australian mammal adapted for a life in a freshwater environment.
It has an unfortunate common name at immediately gives it a bad
reputation. Some sources say that it can grow up to 1m long, but
a more conservative figure is 46-66cm. Even so, it is the largest
rodent in Australia.Water rats sleep during most of the night and hunt around sunrise and sunset, and can sometimes even be spied during the day when there is abundant food. Their diet consists largely of smaller animals including crayfish, mussels, snails, fish, young birds, bird's eggs, and large insects. They take their food out of the water to a midden where they eat and leave broken mussel shells and other refuse.
Breeding can occur at any time during the year but has peaks during spring and summer. Gestation is 35 days and as many as 5 litters (averaging 3-4 young) can be born each year.
Numbers of Hydromys chrysogaster have declinded since European settlement, due partly to extensive hunting for skins which were used to make fashionable fur coats.
Strahan, R. 1987, What
mammal is that?, Angus & Robertson Publishers, Australia.