75.

Highveld Gerbil

Gerbilliscus brantsii

French: Gerbille de Brants / German: Highveld-Nacktsohlenrennmaus / Spanish: Gerbillo de Alto Veld

Other

common names: Brant's Gerbil

Taxonomy. Tatera brantsii A. Smith, 1836,

Ladybrand, eastern Free State Province, near Lesotho border, South Africa. Widely used subspecific name perpallida has been changed for gender agreement. J. A. J. Meester and colleagues in 1986 assigned G. brantsii to a so-called “ afer group,” and molecular studies by P. Colangelo and team in 2007 confirmed close relationship of G. brantsii to G. afer, the two having same standard karyotype. Some breeding experiments, however, indicated post-mating isolation and hybrid sterility. The two species are allopatric. The constitution of the species has been discussed, with some geographical variability observed and one subspecies described. Two subspecies recognized.

Subspecies and Distribution.

G.b.brantsiiA.Smith,1836—SEAngola,SWZambia,ENamibia,Botswana,WZimbabwe,SouthAfrica,andL.e.,withisolatedrecordsfromNZimbabweandNMozambique. G. b. perpallidus Dollman, 1910 — Ngamiland, NW Botswana.

Descriptive notes. Head-body 96-164 mm, tail 103-186 mm, ear 12-34 mm, hindfoot 19-47 mm; weight 25-126 g. A medium-sized gerbil, the Highveld Gerbil exhibits rufous-brown to pale reddish dorsal pelage and pure white to buff-gray ventral pelage. Tail is slightly longer (106%) than head-body length,is the same color as the dorsum basally and white display. Tympanic bullae are moderately inflated (26% of skull length). Females bear three or four pairs of mammae. Chromosomal complement has 2n = 44, FN = 66.

Habitat. Highveld Gerbils are generally caught in sandy soils and sandy alluvium in grasslands or bushlands of the Highveld Plateau and the south-west arid zones. They can be found also in peaty soils around marshes and pans, in Burkea (Fabaceae) woodland or in cultivated fields.

Food and Feeding. Highveld Gerbils are primarilyherbivorous, and insects represent only 5% of their diet. They prefer green parts of plants and roots, and are known to maintain plant diversity in savanna habitats.

Breeding. Reproduction can occur throughout year, with peak at beginning of dry season. After 22 days of gestation, female gives birth to litter of 1-5 (average 2-8) offspring. Young are altricial and are weaned at day 28.

Activity patterns. Highveld Gerbils are strictly nocturnal, with crepuscular peak of activity. Their burrows are long (up to 6 m) and complex, with many entrances and interconnected tunnels; they are sited 20 cm underthe soil, and nest chamber is covered by sealed loose sand.

Movements, Home range and Social organization. The Highveld Gerbil can be abundant in some parts ofits range and 12-16 ind/ha have been noted. It is a non-aggressive species, living in colonies of several individuals. Individuals communicate with two kinds of ultrasonic whistles.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Highveld Gerbil is locally abundant locally and often an agricultural pest. There are no known threats to this species.

Bibliography. Colangelo et al. (2007), Dempster & Perrin (1991, 1994), Dempster, Dempster & Perrin (1992), Happold (2013a), Korn & Korn (1989), Meester et al. (1986).