The Diet of Breeding Brown Falcons ('Falco berigora') In the Canberra Region, Australia, With Comparisons To Other Regions

Abstract

Brown Falcons ('Falco berigora') are generalist predators that take prey from a range of different taxonomic groups. Further, this species is one of the most widespread raptors in Australasia, providing great scope for dietary flexibility. However, few studies have reported on the diet of this species, and none in any detail for the relatively dry, continental climate of the Canberra region of southeastern Australia. We therefore examined this species' diet from 29 collections of prey remains and pellets from 20 nesting territories over five breeding seasons of Brown Falcon pairs breeding within 40 km of Canberra in 2002-06 and again in 2009. A total of 307 prey items was recorded, 15 of which were novel for this species. These novel prey items largely reflected locally common species that were of a similar size and niche to prey previously recorded in other regions, such as a new prey species of quail or beetle. Unusual prey included garden snails ('Helix aspersa') and an owl, the Southern Boo book ('Ninox novaeseelandiae'). Other infrequently captured prey items such as freshwater mollusc's ('Corbicula australis' and 'Glyptophysa gibbosa') and crayfish ('Cherax' sp.) illustrated the extraordinary dietary flexibility of Brown Falcons. In comparison with previous detailed studies, Canberra-based pairs had a relatively small geometric mean prey weight of 7.7 g, and tended to take a higher proportion of invertebrates across a relatively narrow niche breadth. When biomass was considered, rabbits ('Oryctolagus cuniculus') were an important food source, making up half of the total biomass in the diet.