THE INFLUENCE OF HABITAT ON THE DISTRIBUTION AND ABUNDANCE OF PEREGRINE AND LANNER FALCONS IN SOUTH-AFRICA

The distribution and abundance of Peregrine and Lanner Falcons in Sout h Africa was compared using recorded sightings from various sources, i ncluding the Southern African Bird Atlas Project. Falcon distributions were compared with the distribution of cliffs and vegetation, to quan tify differences in the habitat preferences of the two species in the breeding and the non breeding seasons. Lanner Falcons outnumbered Pere grine Falcons in most areas by at least 10:1. Peregrine Falcons were m ore habitat specific than Lanner Falcons, in terms of topographic and biotic requirements. Peregrine Falcons were largely restricted to high cliff areas throughout the year and there probably were no large-scal e seasonal movements within the population. The bulk of the resident P eregrine Falcon population was found in the fynbos biome, in the south western Cape. Outside of this area, Peregrine Falcons were concentrate d in woodlands. Lanner Falcons were less dependent on high cliffs, alt hough cliff availability was important in defining the ranges of both species. Lanner Falcons were most common in the sour grasslands in the east of the country in the breeding season, with apparent movements i n the non-breeding season into the fynbos, the Nama Karoo and the sout hern Kalahari. Overall, Peregrine Falcons favoured relatively closed h abitats and Lanner Falcons favoured relatively open habitats. The diff erences in the two species' habitat preferences are proximate factors influencing distribution and abundance.