Les conséquences d'un supplément alimentaire sur la dynamique des populations de rongeurs au Sénégal. II - Le cas de Taterillus pygargus en zone sahélienne

Abstract

A food supplement was provided every second day during the nine months of the dry season to a population of the gerbil Taterillus pygargus on the former IBP study site of Fété-Olé, Northern Senegal. The effects of this supplementary food were assessed by comparison with the population of a control quadrat set up in the same dry bush savanna. During the first three months of food provisioning, a spectacular increase of Taterillus pygargus numbers was noticed on the provisioned quadrat (QA), as compared to the control area (QT). This was entirely due to a concentration of mature individuals, mostly adult males. Food provisioning also had a beneficiai effect upon the growth curve of young individuals, and on the adult body weight, in both sexes. The breeding season of the females was also lengthened on the provisioned quadrat, but the production of young was not significantly different on the two quadrats. However, food provisioning du ring the lean part of the year was unable to prevent or slow down the sharp population decline of this species which took place from January to June 1977, at Fété-Olé as well as all over Northern Senegal. Such a population crash cannot therefore be ascribed to a mere shortage of foo