Aspects of the Life History and Foraging Ecology of the Endangered Akiapolaau

Relative abundance, breeding ecology, annual survival, home range, and foraging ecology of the Akiapolaau (Hemignathus munroi), an endangered Hawaiian honeycreeper, were studied on the island of Hawaii. The species is a specialist; Akiapolaau used koa (Acacia koa) for foraging much more than expected based on koa availability, and most Akiapolaau occurred in old-growth koa and ohia (Metrosideros polymorpha forests. Male Akiapolaau most often foraged on the trunks and large branches of koa, whereas females used small branches and twigs. The longer bill of males is apparently adapted to the greater bark thickness of larger branches. Lichen-covered and dead branches were preferred feeding sites. Akiapolaau showed serial monogamy and had a relatively low reproductive rate of 0.86 young per par per year, with a long parental dependency period. Home range sizes averaged 10.7 ha and did not differ between males and females. Annual survival for adults was 0.71. Avian diseases appear to restrict Akiapolaau to higher elevation forests where mosquitos are rare. Protection of remaining old-growth koa and ohia forests above the mosquito zone are critical to the survival of the species. Geographic Description: Akiapolaau were studied at five study sites on Hawaii: Keauhou Ranch (19.52, -155.33; 1,740 m elevation), Kilauea Forest (19.52, -155.32 1,630 m), Hamakua (19.78 -155.33; 1,770 m), Kau Forest (19.22, -155.65; 1,750 m), and a Dry Forest site (19.82, -155.55 1,865-2,800 m). 1.5.2 Bounding Rectangle Coordinates Methodology: 25-162 stations were surveyed each month at each study site using the variable circular-plot method with 8-minute counts (Scott et al. 1986) to obtain indices of Akiapolaau abundance.