Movements by birds in Acacia savanna in southeast Botswana

In Botswana where rainfall is unpredictable and often highly localised, thi s results in resources being patchy. Many bird species are therefore nomadi c to some degree. Movements of many, even common, species are, however, ver y poorly understood. This paper looks at patterns of movement in six specie s in mixed Acacia savanna at Ruretse in southeast Botswana using both trans ect and ringing data. Sedentary species such as Sabota Lark Mirafra sabota and Kalahari Scrub-robin Erythropygia poena typically had a high frequency of occurrence and were common on transects, but low numbers were ringed. Th ere was some evidence for seasonality in occurrence for Namaqua Dove Oena c apensis, Marico Sunbird Nectarinia mariquensis and Green-winged Pytilia Pyt ilia melba. One species showed erratic movements, apparently in response to rainfall,whilst two species clearly showed nomadic behaviour.