Patterns of supra-canopy flight by pigeons and parrots at a hill-forest site in Papua New Guinea

It is important that conservation strategies consider the needs of taxa that range over large areas or make significant daily or seasonal movements across areas or habitats, but data on movements in most tropical animal species is lacking. We examined frequency, direction, and temporal variation in supra-canopy flight activity (number of individuals recorded per hour of recording) of eight species of parrot and seven species of pigeon over 5 months in a New Guinean hill-forest. Papuan Mountain Pigeon (Gymnophaps albertisii) contributed 44% of all flights and Sulphur-crested Cockatoo (Cacatua galerita) 17%; while 95% of 1800 flights were made by seven species. Directions of flights were non-random in nearly all species. There was a significant movement of Papuan Mountain Pigeon, and smaller movements of Dusky Lory (Pseudeos fuscata), Rainbow Lorikeet (Trichoglossus haematodus) and Eclectus Parrot (Eclectus roratus), towards lower altitudes in the mornings and a varying return to higher altitudes in the afternoons. Most species made more supra-canopy flights in the mornings than the afternoons but the exact patterns of flight differed between species. Flight activity varied significantly between months in several species, and flight activity tended to be highest during periods of breeding in most frugivorous birds. Large-bodied species made more supra-canopy flights than did smaller species, but there was no relationship across species between ‘on-the-ground’ bird densities and flight-frequency. Breadth of frugivorous diet (determined by review of the literature) did not influence flight-frequency. The factors that underpin the highly variable patterns of movement were identified. How these patterns might be affected by changes in land-use is important for landscape-level conservation, especially for those species that make systematic long-distance movements.