Characteristics of Peregrine and Lanner Falcon nesting habitats in South Africa

Peregrine Falcon, Falco peregrinus, and tanner Falcon, F: biarmicus, nestin g habitats in South Africa ore described in terms of nest ledge, nest cliff and scree slope parameters, and the environmental context of each site. Da ta were collected in a tropical study area where Peregrines and Lanners occ urred in sympatry, from an allopatric south temperate Peregrine population, and opportunistically for both species from other sites throughout the cou ntry. Elevation, ledge size, cliff size and vegetation structure accounted for about 80% of the variation in falcon nesting habitats between species a nd between populations within species. Peregrines used larger nest ledges o n higher, more elevated cliffs than Lanners, overlooking more open, structu rally complex vegetation. Temperate Peregrines used smaller ledges on lower cliffs, overlooking vegetation that provided less refuge for overflying pr ey than subtropical pairs. temperate Peregrines selected nest sites to mini mize the negative effects of spring rainfall. Tropical Peregrines may have selected sites to maximize hunting and provisioning efficiency.