Defence behaviour of Red-footed Falcons Falco vespertinus in the breeding period and the effects of disturbance on breeding success

Abstract

Near the village Melenci (Voivodina, northern Serbia) there were 22 Red-footed Falcon Falco vespertinus nests in 1991 in which offspring had been successfully brought up. The contents of four nests were checked daily from the start of incubation until the fledglings left the nests. Breeding success did not differ between the group of 4 nests disturbed by inspections and the remaining 18 . Despite the fact that the ratio of parent bird presence (both, only female, only male) and absence differed in the comparison of the four nests, Red-footed Falcon parents were usually found in the close surroundings, i .e . they attended their nest . The attendance of the birds to the nests differed between the sexes during incubation as well as hatching and the nestling period, which fact can be interpreted as a difference between the roles of females and males. In 59% of the cases it was the female, while in 41% it was the male bird that was sitting on the eggs. At the time of hatching it was mostly the female (female 86%, male 14%) that was present in the nest, while after hatching it was only the female. Later on the adult birds usually took off from the branch supporting the nest, from neighbouring trees, or from abandoned Rook Corvusfrugilegus nests, rather than from the nest itself. Females participated more times in the defence of the nest than males, yet the ratios of the studied types ofbehaviour (alarm, repellence, attack) did not differ between the sexes. However, significant difference appeared to be present between four nests when the distribution frequency of the three behaviour types was looked at . The distribution of the reaction types of the parent birds to disturbance was significantly different in the periods of incubation, hatching and nestling, respectively . As nesting proceeded and parental investment grew, the number of repellences and attacks increased proportionally .