Variation in the quality of parental care at falcon nests in South Africa as evidence for postulated differences in food availability

Parental care by Peregrine Falcons Falco peregrinus and Lanner Falcons F. b iarmicus during the nestling period was studied in two areas of South Afric a. Comparisons were made between the quality of care administered to broods of Peregrine Falcons at nests in tropical (the Soutpansberg) and temperate (the Cape Peninsula) environments, and to broods of sympatric congeners (P eregrine Falcons and Lanner Falcons) in the tropics, to investigate postula ted species- and area-specific differences in food availability. Time-lapse photography was used to measure provisioning rates and adult attendance at nests. In all three study populations, provisioning rates were positively correlated with brood size, and attendance was negatively correlated with t he age of young. The quality of parental care provided by Cape Peninsula Pe regrine Falcons and Soutpansberg Lanner Falcons was superior (provisioning rates were over 20% higher and adults were more attentive at the nest) to t hat of Soutpansberg Peregrine Falcons. Direct observations and diet informa tion from the analysis of prey remains suggested that female participation in the foraging effort was greatest at Peregrine Falcon nests in the Soutpa nsberg, which may have compromised nest security. The relatively poor quali ty of parental care by Peregrine Falcons in the Soutpansberg is symptomatic of food shortage for this specialist raptor in the tropics, in contrast to the more generalised Lanner Falcon.