Russet batomys  (Batomys russatus)

Classified as Endangered (EN) on the IUCN Red List (1).

Only named and described as a new species as recently as 1998 (3), the russet batomys is known from just two specimens collected in 1975, and one in 1995 (1) (3). A relatively large and attractive mouse, it has a stout body, broad head, large eyes and ears, long facial whiskers, broad, long hind feet, and a tail that is shorter than the length of the head and body (2) (3). There is a narrow ring of bare skin around the eye (2). The thick, sleek fur (2) (3) (4) is, as the name suggests, reddish-brown on the upperparts and bright orange-grey on the underparts, with white front feet and a reddish-brown patch on the tops of the hind feet. The tail is thinly haired and uniformly brown in colour, with a thin tuft at the tip (2) (3). One specimen had a white patch on the throat and chest (3).

Together with its smaller size, the distinctive fur colour helps distinguish the russet batomys from other Batomys species, which are larger and darker, with dark patches on the front feet (3) (4) (5). Interestingly, the russet batomys is unique in possessing a primitive pattern of blood vessels in the head, a feature shared by no other living members of the Muridae family, although it is present in many species of ‘rats’ and ‘mice’ of the family Cricetidae (3) (6).

The russet batomys is endemic to Dinagat Island, a small, mountainous island off the northeast coast of Mindanao, in the Philippines (1) (2) (3) (5) (6). It may potentially be more widespread, possibly occurring on the nearby islands of Siargao and Bucas Grande, but surveys are needed to determine this (1).

The russet batomys has been captured in lowland tropical forest at elevations of around 350 metres (1) (2) (3) (6).

Very little is known about the biology of this poorly-studied mammal. It is suspected to be active at night and to live on the ground (2) (3), and, like other Batomys species, is likely to feed on a variety of leaves, seeds and fruits (3) (4).

Information on the russet batomys is lacking, but it is believed to have a small global population and to be declining as a result of habitat loss on Dinagat, due to agriculture, mining and illegal logging (1) (2). As with many islands in the region, little of the original forest cover may now remain (7). This species is not thought to be very tolerant of habitat disturbance, and its small and highly fragmented range puts it at even greater risk of extinction (1), but little information is available on its exact status (2).

There are not known to be any specific conservation measures currently in place for this poorly-known mammal. Surveys are needed to confirm whether the species occurs on any other islands and to assess its tolerance of habitat disturbance (1), and it may also benefit from further research into its ecology and behaviour.

View information on this species at the UNEP World Conservation Monitoring Centre.

To find out more about the russet batomys and other Philippine mammals, see:

• The Field Museum of Natural History - Synopsis of Philippine Mammals:
  http://www.fieldmuseum.org/philippine_mammals/