EFFECTS OF WOODLAND MODIFICATION BY AFRICAN ELEPHANT LOXODONTA-AFRICANA ON BIRD DIVERSITY IN NORTHERN BOTSWANA

Bird diversity was assessed by point-transect-count sampling during th e dry and the wet season in riverine gallery woodland and in Colophosp ermum mopane woodland with different levels of elephant impact. Dramat ic woodland degradation did not result in a dramatic overall reduction in bird diversity, but resulted in substantial changes in bird specie s composition and capacity for migrant birds. Less affected, more dens e woodlands functioned as dry season refuges for 'resident' Afrotropic al species, but this function was lost in degraded woodlands. In contr ast, secondarized habitat had a much higher capacity for long distance migrants in the wet season. Species endemic to the sub-region and sub species with restricted ranges centred in the area were not negatively affected by woodland degradation. The cumulative interference of past and current elephant numbers with the conservation of bird diversity appears to be insignificant in northern Botswana.