Demography of an introduced red-billed Leiothrix population in Hawaii

Relative abundance, timing of breeding and molting, annual survival, and philopatry of an introduced population of Red-billed Leiothrix (Leiothrix lutea) were studied at four sites on the island of Hawaii. Numbers of leiothrix on our study areas showed a regular cyclical pattern, with highest numbers during the breeding season. Peak breeding occurred May-August, followed by peak molting of flight and body feathers in August-October. Flocking behavior increased post-breeding, and many leiothrix left the study areas during the fall and winter months. Populations on two intensive study areas were stable, with high annual survival (x ± SE = 0.581 ± 0.115 for hatching-year birds and 0.786 ± 0.047 for adults). Leiothrix seem to be relatively unaffected by avian diseases that have decimated some Hawaiian bird populations, and yet reasons for their large historical population fluctuations remain unexplained.