SEASONAL POPULATION DYNAMICS OF RODENTS OF MOUNT CHILALO, ARSI, ETHIOPIA

Abstract

A study on seasonal population dynamics of rodents was carried out on Mount
Chilalo from August, 2007 to April, 2008. Six habitats, namely grassland, bush land, montane forest,
Erica forest, Afroalpine forest and moor land were identified to carry out live and snap trapping
during wet and dry seasons in randomly selected grids. Seasonal species distribution, relative
abundance and habitat association, weight, sex, age and reproductive status of rodents were
studied. From 1,756 individuals captured, 985 (56.1%) and 771 (43.9%) were live trapped during wet
and dry seasons, respectively. Species composition for live trapped individuals during wet and dry
seasons was 9 and 10, respectively. These are: Arvicanthis abyssinicus, A. blicki, Lophuromys
flavopunctatus, L. melanonyx, Mastomys natalensis, Mus mahomet, Otomys typus, Stenocephalemys albipes,
S. albocaudata and S. griseicauda. Mus mahomet was trapped only during the dry season. There was
no significant seasonal variation in the capture of young and sub-adult, while it is significant among
adults with highest during wet season. Although more males than females were trapped during
wet season, the sex ratio was not significantly different. The number of reproductively active males
and females were higher during the wet than the dry season. The highest trap success (47.1%) was
recorded during wet season. Biomass ranged from 9,231 g/ha (moor land habitat) to 55,507 g/ha
(grassland habitat). From snap trapped rodents, pregnant females of A. dembeensis, R. rattus and M.
mahomet were not obtained. Maximum number of embryo counted was 15 for M. natalensis and the
least (2) was for O. typus.