Abstract

We report on the non-breeding dispersion and density of Buff-breasted Paradise Kingfishers (Tanysiptera syliva sylvia), an Australo-Papuan intratropical migrant. The study was carried out at the base of the Hunstein Range, in the Sepik basin of Papua New Guinea, using playbacks of calls to census for the presence of birds. Preliminary density estimates (0.4–1.0 birds ha^–1) were higher than expected on the basis of the paucity of museum specimens, the results of broad-scale bird surveys, and observational records. This difference is probably due to their extremely shy behaviour, which would cause them to be under-represented using standard survey methods. Most importantly, at least some kingfishers were territorial, with just a single bird defending each territory. Birds responded to playbacks of their calls using stereotypical territorial responses, and attacked models vigorously. These observations suggest that kingfishers compete for resources at their non-breeding grounds. At least in this species, competition during the non-breeding season may therefore have been a factor in the evolution of intratropical migration, as suggested for the better-studied temperate–tropical migrant species of North America and Europe. In addition, if demographic processes during the non-breeding season are found to limit populations in other Australo-Papuan migrants, the impending massive habitat loss in the Australasian and south-east Asian tropics may have devastating effects on many of these species.