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As part of a three-year study to develop ecologically-based rodent management (EBRM) in
southern Africa, a capture–mark–recapture study was carried out in Tanzania, Namibia and
Swaziland to establish the demographic patterns and population dynamics of rodents. Two
study grids were established in each country. In Tanzania, ten species of rodents and one shrew
(Crocidura sp.) were identified in the study area. The rodent species consisted of Mastomys
natalensis, Aethomys chrysophilus, Arvicanthis neumanni, Gerbilliscus vicina, Acomys
spinosissimus, Lemniscomys griselda, Lemniscomys zebra, Rattus rattus, Graphiurus sp. and
Mus minutoides. Mastomys natalensis was dominant and contributed more than 70% of the
captures. In Namibia, five species were captured, namely Mastomys natalensis, Gerbilliscus
leucogaster, Saccostomus campestris, Mus minutoides and Steatomys pratensis. Mastomys
natalensis contributed about 50% of the captures. In Swaziland, only M. natalensis was
captured in the study grids. There was a clear pattern in the population dynamics, with breeding
confined to the wet seasons in the three countries. Mastomys natalensis was the dominant
pest species, for which EBRM should focus on. The highest population density of M. natalensis
occurred during and after the rains, which coincided with the most susceptible phenological
stage of crops. The breeding seasonality and density fluctuations observed in the three
countries conform with observations made elsewhere in Africa, which support the hypothesis
that rainfall events promote primary productivity on which murid rodents depend. Development
of EBRM in these countries will be determined by the local conditions and how they
influence the demographic processes of the rodent populations. EBRM should make use of the
available ecological knowledge of the local rodent pest species and the focus should be on
(ecological) management practices applicable at the community level including community
based intensive trapping, field hygiene, removing cover and sources of food for rodents. |
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