Breeding behaviour and prey of Black Falcons, 'Falco subniger', including food-caching

Abstract

The breeding behaviour and diet of a pair of Black Falcons, 'Falco subniger', and offspring were studied by 110 hours' observation from incubation to the end of the post-fledging period, and by analysis of pellets, on a wooded floodplain in northern coastal New South Wales in 2013. The sexes shared incubation and feeding of chicks, and delivery of food to the fledglings. Delivered prey was entirely birds in the nestling period (n = 38), and almost half mammals (41%) by number in the post-fledging period (n = 34; rats ~50% of prey biomass in that phase). The adults cached prey, mostly in tree hollows. Parental feeding rates were 0.7 prey item/h (~70 g of prey biomass/h) delivered in the nestling period, and 0.4 item/h (~80 g of prey biomass/h) in the post-fledging period (initially 0.5-0.6 item/h, declining to 0.2/h in the final weeks). Adult behaviour and vocalisations, and growth and development of nestlings and fledglings, are described. The nestling period lasted 42-43 days, and the post-fledging period lasted two months for two surviving juveniles (of four fledged); fledglings died during a storm and from vehicle strike. Supplementary observations of displays, vocalisations, hunting behaviour and prey are provided for a site in northern inland NSW.