Breeding of the Peregrine Falcon in Victoria, Australia

Abstract

This study was conducted from September to December, in both 1976 and 1977, to investigate the demography and ecology of the Victorian Peregrine Falcon. At least 200 nesting areas were discovered and we report data on ninety-five sites throughout the State. The most common nest site (62 of 95) was a cliff (vertical escarpments, stone quarries and rocky knolls). Nest sites in trees were in hollows (17) and in stick nests of other birds (16). Extreme variation in selection of nest sites was observed. Exposure of cliff sites was significantly related to fledging success.

Laying began in late August and the last young fledged in early December. The onset of breeding in 1977 was seven to ten days earlier than in 1976 in correlation with warmer drier conditions that spring. Clutch size averaged 2.81 and brood size, 2.24, for all sites hatching young. Over half (59.8%) of the occupied sites fledged young for a net productivity of 1.21 young per occupied site (2.02 young per successful site). Non-breeding adults occurred at 15.2 per cent of the occupied sites.

Prey consisted of small to medium sized birds and a few mammals. Eighty-nine species of bird were identified as prey but three (Feral Pigeon 20%; Galah 15%; and Common Starling 16%) were the most important. Parrots as a group made up thirty-six per cent of the diet.

Results are discussed in light of studies of Peregrines from northern temperate areas and comparisons made regarding breeding schedules, productivity and selection of nest sites. The Victorian Peregrine appears more adaptable to variation in habitat than most populations and, at least superficially, stability of the population is suggested by most aspects of its breeding ecology.