BATS IN RIVERINE FORESTS AND WOODLANDS - A LATITUDINAL TRANSECT IN SOUTHERN AFRICA

Using captures in mist nets and monitoring echolocation calls, we quan tified bat distribution and activity and measured insect abundance as numbers of insects attracted to black lights at 15-min intervals. Thes e data were collected simultaneously at pairs of sites in riverine and dry woodland savannah along a transect of ca. 350 km from north to so uth in the Kruger National Park, South Africa. The sites were situated in the north, central, and south of the park and data were collected in January 1993. Our study involved 18 sites, three pairs each in the areas of the Luvuvhu, Letaba, and Sable rivers. Half of the sites were in riverine woodland, the others in dry woodland. No statistical asso ciation exists between bat captures and either bat activity or insect abundance. Bat activity, however, was related significantly to insect abundance. Although bats were significantly more abundant (captures) i n riverine habitats than in dry woodland savannah, comparisons of bat diversity and evenness (rarefaction curves, species abundance curves, and Whittaker plots) showed no differences between these habitats. The data neither demonstrate a decline in bat diversity away from the equ ator nor suggest specific bat communities associated with riverine hab itats. The data do demonstrate the important influence of insects on t he activity patterns of insectivorous bats.