112.

Nigerian Gerbil

Gerbillus nigeriae

French: Gerbille du Nigéria / German: Nigeria-Rennmaus / Spanish: Gerbillo de Nigeria

Other common names: Dallon’s Gerbil

Taxonomy. Gerbillus nigeriae Thomas & Hinton, 1920,

“Farniso, near Kano, North Nigeria (altitude 1,700 ft. [= 518 m]).”

Although most authors treat G. nigeriae as a valid species, F. Petter in 1975 and D. Kock in 1978 regardedit as a synonym of G. agag . G. nigeriaeis characterized by an ex-tensive chromosomal polymorphism due to extensive Robertsonian translocations and variations in quantity and distribution of heterochromatine, and V. T. Volobouev and colleagues in 1988 considered it a model for the understanding of these types of cytogenetic modifications. A. Ndiaye and colleagues in 2014 found G. nigeriae to be close to G. andersoni . This is one of nine endemic West African sahelian gerbils. Monotypic.

Distribution. Known from W Mauritania, N Senegal, Mali, Niger, N Burkina Faso, N Nigeria, and W Chad.

Descriptive notes. Head—body 74-106 mm,tail 104-160 mm, ear 11-16 mm, hindfoot 23-31 mm; weight 14-43 g. Slight sexual dimorphism was found in weight, head-body length, and ear length, with malesa little larger than females. Karyotype 2n = 60-74. The Nigerian Gerbil is a small gerbil with pale sandy to ocher dorsal pelage and pure white venter. Long tail (110-130% of head-body length) ends in a pencil of dark hairs. Preorbital, supraorbital, and post-auricular patches of white hairs are visible, and forefeet and hindfeet also are white. Females have four pairs of mammae.

Habitat. Sandy habitats, but is found regularly in cultivated (millet) and fallow fields. Can be found also in houses.

Food and Feeding. In Burkina Faso, diet consists of seeds, arthropods, and green vegetation in wet season and of seeds alone in dry season. It stores seeds in burrows to survive estivation periods.

Breeding. Reproduction and birth occur during wet season, but female has estrous cycles throughoutyear. Litteris of 2-6 young (average 3-4). Pregnant females bear 2-8 embryos (average 4-2).

Activity patterns. The Nigerian Gerbil is nocturnal and terrestrial. Burrows are simple and are built in surface layer during dispersal, but are deeper and more complex during pre-estivation and estivation.

Movements, Home range and Social organization. Nigerian Gerbils are solitary and territorial; aggressive behavior toward other individuals are observed in captivity. Home ranges of males overlap those of females during breeding times. Home ranges are smaller (c.1000 m2) in reproduction period than during dispersal (c.1600 m?) and pre-estivation (c.2100 m?). In north Burkina Faso, the Nigerian Gerbil stores food in burrows in pre-estivation period from mid-January to February, and then estivates during March—-May (dry hot season). In Niger, estivation period was not observed. It can reach two years of age in captivity. It may be abundant locally, and population size fluctuates; up to 150 ind/ha have been counted and the species is then considered a pest. Recentstudies have shown that this species invaded Senegal during last 10-15 years.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Nigerian Gerbil is abundant and has a wide distribution.

Bibliography. Ba et al. (2006), Dobigny, Nomao & Gautun (2002), Happold (2013a), Granjon & Duplantier (2009), Granjon, Brudereret al. (2002), Kock (1978b), Monadjem et al. (2015), Musser & Carleton (2005), Ndiaye et al. (2014), Nomao & Gautun (2001), Petter (1975a), Sicard (1992), Sicard & Fuminier (1996), Sicard & Papillon (1996), Thiam et al. (2011), Tranier (1975), Volobouev et al. (1988).