The season, frequency, parental care and success of breeding Black-necked Storks 'Ephippiorhynchus asiaticus australis' in northern New South Wales

Abstract

The Black-necked Stork 'Ephippiorhynchus asiaticus' is a large waterbird native to Australasia whose breeding biology is poorly known. They are known to breed as solitary pairs within large home ranges making detailed breeding studies difficult. We investigate the breeding biology of eleven regularly monitored pairs over a four-year period (2003-2006) in northern New South Wales. They were found to breed from May to January, with incubation from May to October, nestlings from July to January and fledging from September onwards. Individual pairs bred approximately twice over the four-year period. There was no tendency for successful years to be followed by a non-breeding year and pairs were capable of rearing young in successive years. Both parents shared nesting duties, with males spending more time than females brooding the nestlings (68%). The first three years had average or below average rainfall, but 2006 had good rain in summer and autumn. More Storks bred in that year and produced more fledglings per active nest (1.7) than in the previous three years (mean of 1.3 fledglings/active nest). Juveniles remained with their parents for at least two months, though they started foraging by themselves soon after leaving the nest. One young bird was found dead 400 kilometres NNE of its nest, within four months of fledging. The production of at least 64 young in four years suggests that the recruitment rate is likely to be adequate to maintain the state's population of this presumably long-lived species.