Observations on the Broad-toothed rat, Mastacomys fuscus Thomas

Abstract

The broad-toothed rat, Mastacomysfuscus, is a relict species surviving in isolated colonies in New South Wales, Victoria, and Tasmania. It was much more widespread in the Pleistocene to Recent and its decline was probably due to long-term environmental changes. A study was made on the only known colony in New South Wales, at Whites River, Kosciusko State Park. Systematically, this population is not separable from the modern Victolian subspecies, bvazenori. In this cold, wet, elevated habitat the rat and other small mammals live along small creeks among shrubs and long grass which are covered by snow during winter. The snow is held up by the shrubs and the microclimatic conditions beneath the snow are relatively mild. In other localities the climate is wet and cool to cold and the rat lives in shrub and grass communities. Mastacomys was bred in captivity for the first time. Four litters, one of which was conceived in the wild, were born in captivity in December-March, and an advanced pregnant female was trapped in February. A pregnant female was trapped in Victoria in October. Evidence suggests a long gestation period, and it has small litters of precocious young which attach tenaciously to the teats and are dragged around by the mother, a habit widespread in the Pseudomyinae. Soon after the birth of the young (presumably after post-partum meting) the female becomes dominant and savagely attacks the male if he comes near her. Photographs of a living Mastacomys are published for the first time.