Recent increase in knowledge about numbers and flight behaviour in the White-throated Needletail Hirundapus caudacutus

Abstract

I have reviewed data from Australian and Asian published sources and from my own observations in Victoria, New South Wales and Queensland as well as from hundreds of observers who have sent their observations directly to me for the decade 2011–2020. These data show that the average flock size of the White-throated Needletail Hirundapus caudacutus in Australia was 33, being nine smaller than the average for the previous decade. In the decade 2011–2020, we have also learnt that many of these birds migrate through southern Thailand to Malaysia, then into Indonesia following the archipelago to Papua New Guinea and then across Torres Strait to Cape York. We have also learnt that at least some of those breeding in northern Japan fly from various parts of Japan westwards to China, then southwards, then back eastwards over the Pacific Ocean passing north of the Philippines until north of New Guinea. Then they fly southwards over New Guinea to reach Cape York. When departing, these birds fly westwards over Australia, then northwards, leaving Australia from Western Australia or the Northern Territory. While in Australia, they are almost constantly on the move and, because they fly for 1–2 hours after dark as well as before sunrise, they can collide with and be killed by the blades of wind turbines. The ongoing loss of nesting hollows in the Needletail’s breeding grounds is still likely to be a major cause of the species’ decline, but wind turbines in Australia may present a new and emerging risk and further research is required to determine whether or not the numbers killed are significant. Experiments in Japan have shown for the first time that this species will nest in man-made nest boxes.