TITLE: THE BUSH KAROO RAT

There are a lot of bush Karoo-rats at our field-site, and even one in our “garden ” at the research station. We tagged them too, for studies which might be done by diploma-students in the future. Tagging them is a bit more difficult than tagging striped mice as they are bigger and also stronger. This also explains why striped mice are often chased away from bush karoo rats ’ nests. Striped mice and bush Karoo rats often compete for nesting sites and both appear to prefer the shrubs of the genus Lycium. Previously, striped mice only occasionally used bush Karoo rat nests but were often chased away from them by the rats. However, when the rats became locally extinct in 2003 after a severe drought, the mice took over the nests of the rats. This indicates that normally the larger rats monopolize the best nesting sites. In 2004, when we had more rain, the rats came back, emigrating from a neighboring farm. They did not build new nests but took their nests back from the mice, forcing the mice to nest elsewhere. Systematics There are 10 species of Otomys, all confined to Africa. Six of them occur in southern Africa. It has been discussed before whether the bush Karoo rats belongs to the genus Otomys at all, because its dental characteristics and bull inflation are actually more similar to the whistling rats of the genus Parotomys. In any case, bush Karoo rats have nothing to do with the Norwegian rat, but belong to their own sub-family Otomyinae (to whom the whistling rats belong also)