Sminthopsis crassicaudata
fat-tailed dunnart

This species occurs in the extreme southern portions of Queensland, Australia.

Fat-tailed dunnarts typically have a head and body length of 64- 110 mm, and a tail length of 51-12 mm. They range from buffy to brownish in color, and have dark patches on their ears and head.

This species is polyestrus. Females may breed and raise litters continuously for up to six months if environmental conditions are favorable. Nearly all of the breeding in this species occurs between July and February. Gestation ranges from 13 to 16 days, and litters of up to ten young may be produced. The young first protrude from their mother's pouch at the age of 37 days. They disperse from their natal range when they are 65-69 days old. Females attain sexual maturity more quickly than males. They are capable of becoming pregnant when they are 155 days old. Males, however, are not capable of breeding until they are 159 days old.

Fat-tailed dunnarts are nocturnal and appear to live in small groups. Although little is known about their social system in the wild, captive study has shown that females are not receptive to the presence of males after they have given birth to a litter. Males housed with females who have litters are often killed by the females. This suggests that females with young may be territorial and solitary in the wild. Fattailed dunarts, like many marsupials, have poorly developed thermoregulatory abilities. In the colder months, they may enter into a thermoregulatory mutualism with Mus musculus. Huddling together for warmth, both species are able to reduce their energetic costs. Mixed species aggregations are common during the winter, and there is a low incidence of natural torpor.

The fat-tailed dunnart eats a variety of grasshoppers, moths, and beetles.