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)
Though there is little information available on the mating behavior of white-tailed rats, it is known that they can have litters of at least 6 in the wild. A female of this species was captured in late October with 6 well-formed embryos. Similarly, individuals held in captivity produced litters of 6 young. Unfortunately no other information about the offspring is reported (Carleton and Goodman, 2003)
Little is known about parental care in white-tailed rats. Observations suggest males may remain nearby after offspring are born and defend the nest while the female takes care of young. (Carleton and Goodman, 2003)
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)
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 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 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)
Scott Birkinshaw (author), University of Oregon, Stephen Frost (editor, instructor), University of Oregon, Tanya Dewey (editor), Animal Diversity Web.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
uses sound to communicate
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
A substance that provides both nutrients and energy to a living thing.
an animal that mainly eats fruit
An animal that eats mainly plants or parts of plants.
animals that live only on an island or set of islands.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
1975. The Cricetid Rodents. Pp. 318-319 in B Grzimek, ed. Grzimek's Animal Life Encyclopedia, Vol. 11, 2nd Edition. New York: Van Nostrand Reinhold Company.
Baillie, J. 2006. "Brachytarsomys albicauda" (On-line). IUCN Red List of Threatened Species. Accessed January 26, 2009 at http://www.iucnredlist.org/details/2991.
Carleton, M., S. Goodman. 2003. Rodentia: Brachytarsomys, White-Tailed Tree Rats, Anstangy. Pp. 1368-1370 in S Goodman, J Benstead, eds. The Natural History of Madagascar. Chicago: The University of Chicago Press.
Garbutt, N. 2007. Mammals of Madagascar. New Haven, Connecticut: Yale University Press.
Miljutin, L. 2008. Probability of competition between introduced and native rodents in Madagascar: An estimation based on morphological traits.. Estonian Journal of Ecology, 57: 133-Â–152. Accessed February 15, 2009 at http://kirj.ee/public/Ecology/2008/issue_2/ecol-2008-2-133-152.pdf.
Nowak, R. 1991. Walker's Mammals of the World. Baltimore: The John Hopkins University Press.