Restricted to isolated populations by the sparseness of its habitat, the broad-toothed mouse is at risk from habitat loss, as well as other threats, such as climate change and predation by introduced mammals (1).
Across many parts of its range, the broad-toothed mouse has suffered significant population declines. At Mount Kosciuszko, this species’ population has declined by over 50 percent, most likely due to low snow cover and early snow melt, possibly associated with climate change. Decreased snow cover can lead to higher levels of predation by foxes and feral cats. There is also some evidence to suggest that foxes preferentially prey upon the broad-toothed mouse over other rats and mice in its habitat, perhaps because it occurs in family groups or because it is slower and less aggressive than other rats or mice (2) (7). These threats were compounded by a bush fire in January 2003 that burned approximately 70 percent of the alpine area where this species occurs. In addition, the broad-toothed mouse has not been recorded in the Otway Ranges for the last 30 years (1).
The broad-toothed mouse is particularly vulnerable to the adverse affects of climate change as it is a high altitude specialist (1). It is expected to retreat to higher altitudes in response to climate change; however, where this is not possible, the broad-toothed mouse is at great risk from rapid habitat loss. There is also the potential for it to be exposed to increased competition with native rat species, which are likely to expand in range as the climate changes (8).
Other threats to the broad-toothed mouse include habitat conversion to ski resort developments and habitat destruction and degradation by feral horses, rabbits, hares, pigs. Introduced weeds such as broom species (Cytisus) and an exotic grass, Holcus lanatus, are invading this species’ habitat at Barrington Tops, while willow species (Salix) are a threat in alpine Victoria. In Tasmania, inappropriate fire regimes are a potential threat to the broad-toothed mouse (1).