A COMPARISON OF HUNTING BEHAVIOUR BY LESSER KESTRELS FALCO NAUMANNI AND EASTERN REDFOOTED FALCONS FAMO AMURENSIS IN THEIR NON-BREEDING SOUTH AFRICAN RANGE

Summary

Zank, C.M. & Kemp, A.C. 1996. A comparison of hunting behaviour by Lesser Kestrels Falco naumanni and Eastern Redfooted Falcons Falco amurensis in their non-breeding South African range. Ostrich 67: 63–66.

The non-breeding hunting behaviour of members of mixed flocks of Lesser Kestrels Falco naumanni and Eastern Redfooted Falcons Falco amurensis was studied during January 1991 in the Transvaal Province of South Africa. Both species employed perch-hunting and hover-hunting to catch their insectivorous prey. Only 46.8% of Lesser Kestrel and 49.8% of Eastern Redfooted Falcon strikes were successful, with perch-hunting more successful than hover-hunting in both species (59% vs 39% and 59% vs 41% respectively). Hover-hunting resulted in a significantly higher strike rate (47 strikes.hr⁻¹ vs 14 strikes.hr⁻¹; 34 strikes.hr⁻¹ vs 15.5 strikes.hr⁻¹) and kill rate (18 kill.hr¹ vs 9 kills.hr¹; 14 kills.hr¹ vs 9 kills.hr¹) than perch-hunting for both species. Eastern Redfooted Falcons hovered for significantly longer (6.5 seconds vs 5.5 see) and more often than Lesser Kestrels, but with no significant differences in hover-hunting and perch-hunting strike success, strike rate or kill rate. There were no significant differences in linear dimensions or mass loading between the sexes of both species and Lesser Kestrels showed no significant differences in hunting performance between the sexes. Eastern Redfooted Falcon females had significantly lower strike success (46.9% vs 64%) and kill rate (7 items.hr¹ vs 11 items.hr¹) than males. This may be due to the inclusion of immature birds in the female sample. Under similar environmental conditions, hunting behaviour differed little between the two species or between sexes of the same species, as expected in species with only slight interspecific and sexual size dimorphism.