A rare animal that has always been rare

The New Holland Mouse (Pseudomys novaehollandiae) is a small rodent that lives in near-coastal heathlands and woodlands of Victoria, NSW and Tasmania.  It feeds on a range of seeds, particularly those of peas and wattles, as well as invertebrates, moss, fungi and flowers. The soil in most sites is very sandy and the adults dig deep burrows for breeding.  The mouse is most abundant in areas where the vegetation is relatively young, a time at which seed and flower production, and hence food availability, is at its greatest.   New Holland Mouse is classified as vulnerable in Victoria and Australia, it is listed under the Flora and Fauna Guarantee Act (ACT) and is classified as vulnerable under the IUCN Red List.

Although there is evidence that New Holland Mouse numbers have declined in recent years the species has probably always been rare due to the limited availability of suitable habitat.  Some of the known populations, particularly those near Melbourne, have apparently vanished in the past 30 years and this is a trait that has distinguished the species since it was first discovered.

The New Holland Mouse was first described in 1843 from specimens collected in NSW.  Over the next forty years a number of new specimens were collected but by 1887 no more animals could be found.  By the beginning of the 20^th century it was thought that the species had become extinct and it wasn't until 1967 that it was rediscovered in coastal heathlands near Sydney.  A number of new locations in coastal NSW soon followed and then, in 1970, the first Victorian animal was captured in Tyabb, about 50km south-east of Melbourne.  The species was also recorded in north-western Tasmania in 1976.  Other locations in Victoria followed in the late 1970s, the 80s, 90s and into the 21^st century. 

Curiously the earliest records from Tyabb, Cranbourne and Loch Sport, in the 1970s, all appear to have vanished (at least temporarily) and new populations have been discovered, in the 1990s, in East Gippsland and Wilson Promontory.  It would seem that a preference for vegetation that is young causes populations of New Holland Mouse to decline as the vegetation ages and re-establish after disturbances such as fire and vegetation clearance.  The Cranbourne population, for example, was first discovered in 1973 in a patch of heathland that was recovering from being cleared 20 years earlier.  The numbers of individuals captured reached a peak about three years later and declined steadily afterwards.

The future for New Holland Mouse in Victoria is uncertain but there is little doubt that a range of vegetation ages in areas near to each other will be needed to provide the best opportunities for the species to migrate to suitable habitat once the occupied vegetation can no longer provide an adequate supply of food.