Spatial dynamics of Mastomys natalensis in a field-fallow mosaic in Tanzania.

The population dynamics of Mastomys natalensis rats is reported for a 3-year study of monthly CMR-trapping in a small scale maize field-fallow land mosaic in Tanzania. The seasonal evolution of rodent presence was the same in both habitat types and it was not affected by agricultural activities in the fields. About one week after planting, there was a short increase of rodent captures in the maize fields, but this disappeared again after a few days. Recolonisation of fields was achieved very fast after a rodent control operation. Radiotelemetry indicated that many individuals were active in the maize field as well as in the fallow land. We concluded that, in a small scale set-up, the field and fallow land rodent populations are not separated and the latter should not be considered as necessary refuges. This renders several rodent control approaches unsuitable.