Brachytarsomys albicauda
white-tailed rat

White-tailed rats, Brachytarsomys albicauda, can be found in eastern Madagascar from Marojejy (northeast) to Andringitra Massif (southeast). This is a long narrow strip of land stretching from north to south which has patches of rainforest. This is considered only the extent of their potential range, due to the rarity of human encounters with these rats. They have been confirmed at various locations in this range but not everywhere in it. (Baillie, 2006; Garbutt, 2007)

White-tailed rats have strong, sharp, curved claws. This characteristic and many others indicate a high degree of specialization for arboreal life. that parallels the way it nests in tree holes. They live in tropical forested areas in Madagascar. They nest in tree holes, some have been observed in holes near the base of trees, most have been observed within 2.5 m of the ground. (Baillie, 2006; Miljutin, 2008)

There are two species in the genus Brachytarsomys , B. albicauda is the smaller of the two. Other than size, B. albicauda is distinguished from its cousin, Brachytarsomys villosa (Hairy-tailed antsangys) by its nearly furless tail. Though smaller than B. villosa, white-tailed rats are up to 50 cm long. They are easily identifiable by the white tip on the tail, which averages 230 mm long. White-tailed rats are covered in a thick coat of brownish-grey fur with a white underside. They have short snouts, giving the face a blunt look. (Garbutt, 2007)

The natural lifespan of B. albicauda is unknown. The lifespan in captivity has not been published.

White-tailed rats are nocturnal and arboreal. It is assumed that they spend very little time on the ground. They have specific adaptations that indicate a primarily arboreal lifestyle. For example, they have an elongated fifth digit on the hind feet for better gripping and an unusually long and flexible tail for greater balance. Nest cavities are within hollowed portions of standing tree trunks and these rats travel along branches to reach foraging areas without having to move across the ground. If white-tailed rats are disturbed while on the nest, they will often appear at the entrance and chatter, perhaps to scare away the disturber. This may indicate that they are territorial or protective of young. Little else is documented about behavior. ("The Cricetid Rodents", 1975; Carleton and Goodman, 2003)

Home Range

There is little information about the home range of B. albicauda. It is assumed that individuals stay very close to their nesting area. (Carleton and Goodman, 2003)

Due to its nocturnal and arboreal nature, there have been few observations of white-tailed rat communication behaviors. Like most nocturnal mammals, olfaction is likely to be an important way of sensing the environment. (Carleton and Goodman, 2003)

White-tailed rats are generally described as frugivorous. According to some, their craniodental characteristics would be better suited for a leaf-eating (folivorous) diet. They have short rostra, broad zygomatic arches, relatively wide incisors and a long row of molars that have ridged masticatory surfaces. When offered an assortment of leaves in captivity, white-tailed rats refused to eat them, preferring only fruit. They may also eat seeds. (Carleton and Goodman, 2003; Garbutt, 2007; Miljutin, 2008)

No information on predation of B. albicauda is available. Their nocturnality is an anti-predator adaptation and their brown coloration serves as camouflage. (Nowak, 1991)

No information on the ecological role of white-tailed rats is available. However, they may play a role in seed dispersal through their frugivorous habits.

There are no known adverse effects of B. albicauda on humans.

White-tailed rats are hunted by local people who consider them as tasty as lemurs. (Miljutin, 2008)

White-tailed rats do not appear to be endangered. The IUCN redlist recognizes them as "least concern." However, continuing human-induced habitat changes may impact populations of white-tailed rats negatively. (Miljutin, 2008)

The subfamily Nesomyinae is diverse, with 9 known genera (including Brachytarsomys) and endemic to the island of Madagascar. This degree of endemicity is typical of Madagascar. It is unfortunate that so little is known about many of its native species. The forests of Madagascar continue to shrink due to human destruction and every day the diversity of the island is reduced. (Garbutt, 2007)