13.

Percival’s Spiny Mouse

Acomys percivali

French: Acomys de Percival / German: Percival-Stachelmaus / Spanish: Raton espinoso de Percival

Taxonomy. Acomys percivali Dollman, 1911,

Chanler Falls, Nyiro, Kenya.

Acomys percivali was initially considered a synonym of A. kempi, but H. W. Setzer in 1975 included it in A. cahirinus, an opinion contradictedby many authors as early as 1919. On morphological grounds, C. Denys and colleagues in 1994 found it very close to A. wilsoni, and both species live in sympatry in southern Ethiopia where they are recognized by chromosomal complement of 2n = 36 and FN = 68. Monotypic.

Distribution. SE South Sudan, SW Ethiopia, NE Uganda, and W Kenya.

Descriptive notes. Head-body 82-111 mm, tail 39-92 mm, ear 11-15 mm, hindfoot 9-15 mm; weight 18-48 g. Percival’s Spiny Mouse is a small species of Acomys, with tail c.76% of head-body length. Flanks are gray, and belly is white.

Habitat. Acacia ( Acacia, Fabaceae) and other arid savannas, riverine areas without trees (grass and thickets), and arid slopes and valleys without vegetation. Percival’s Spiny Mouse can dominate rodent fauna of “kopjes” (isolated rock ridges) and rocky habitats in central Kenya (80-100% of small mammals captured) and can competitively exclude other rodent species, including Kemp's Spiny Mouse ( A. kempi). Percival’s Spiny Mice can hide in crevices.

Food and Feeding. Diets of Percival’s Spiny Mice contain more seeds, stems, and leaves in the wet season (10-30%) and intermediate season (45-65%) than the dry season when arthropods (60-95%) dominate their diets.

Breeding. Within each kopje, reproduction is synchronous, with all adult females giving birth in the same time; however, reproduction is asynchronous among kopjes, even those separated by less than 1-2 km. Females were pregnant year-round in Meru National Park, with no relationship to rainfall patterns. Gestation lasts 34-35 days; litters have 1-2 young. At birth, young weigh 4-5-5 g, have hair, and are able to eat solid food. Spines develop at c.5 weeks of age at weights of 8-20 g.

Activity patterns. Percival’s Spiny Mice are nocturnal. They are good climbers and can jump up to 1 m.

Movements, Home range and Social organization. Densities can be as high as 100-300 ind/ha. Percival’s Spiny Mice are highly social and notterritorial. They sleep together and groom each other. Both sexes carry young. Aggression can develop when densities are high. Dispersal among kopjesis low, and marked individuals have been recaptured in the same place after two years.

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

Bibliography. Denys et al. (1994), Ellerman (1941), Hollister (1919), Hubert (1978b), Janecek et al. (1991), Matthey (1968), Neal (1983, 1984), Ogada et al. (2009), Petter (1983), Setzer (1975), Takata (2013).