65.

Black-tailed Gerbil

Gerbilliscus nigricaudus

French: Gerbille a queue noire / German: Schwarzschwanz-Nacktsohlenrennmaus / Spanish: Gerbillo de cola negra

Taxonomy. Gerbillus nigricaudus Peters, 1878,

Ndi, Taita, Kenya .

Although morphologically very close to G. robustus, G. nigricaudus was treated as a valid species by P. J. J. Bates in 1985 and 1988 and by I. Ya. Pavlinov and colleagues in 1990. Chromosomes were described by P. Colangelo and coworkers in 2005. A morphometric analysis by P. Colangelo and team in 2010 showed that G. nigricaudus, G. robustus, and G. vicinus are clearly distinct. Further molecular analysis by L. Granjon and colleagues in 2012 suggested that G. nigricaudus belongs to an East African clade that includes also G. robustus, G. phillipsi, and G. vicinus . Two subspecies recognized.

Subspecies and Distribution.

G.n.nigricaudusPeters,1878—SKenyaandNETanzania.

G. n. nyama Dollman, 1911 — SW Ethiopia, SW Somalia, and N Kenya.

Descriptive notes. Head—body 130-193 mm, tail 170-208 mm, ear 20-24 mm, hindfoot 34-41 mm; weight 80-195 g. Females are smaller than males. The Black-tailed Gerbil is characterized by its long black tail (110% of head-body length). Specimens of nominate subspecies nigricaudus are larger and the tail is black above and below, whereas nyama are smaller and the tail not fully black below. This large gerbil has a brown dorsal pelage and a white venter. Chromosomal complement has 2n = 36, FN = 68.

Habitat. Open woodlands and bush thickets in Somali-Masai savannas, as well as open grasslands, at up to elevations of 1500 m.

Food and Feeding. The Black-tailed Gerbil is omnivorous, with seasonal change in diet composition. In dry season, insects can represent up to 90% of diet, supplemented with some seeds and forbs, while in wet season proportion of vegetable matter increases to up to 50%.

Breeding. Although females can reproduce all year, there are two peaks associated with the two wet seasons per year (November—January, April-May). Females bear 1-8 embryos, and mean litter size is 5-5 in wet season and 4-2 in early dry season.

Activity patterns. Black-tailed Gerbils are nocturnal and terrestrial.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Bates (1985, 1988), Colangelo, Castiglia et al. (2010), Colangelo, Corti et al. (2005), Granjon etal. (2012), Happold (2013a), Monadjem etal. (2015), Pavlinov et al. (1990).