Relative abundance and habitat use of 29 forest bird species, including 22 land birds (18 indigenous breeding residents, 3 exotics, 1 migrant) along with a rail, heron, and five seabirds (shearwater, tropicbird, 3 terns) were assessed on Pohnpei [Island] during summer 1994 and compared with the results of the first survey in 1983. The most frequently encountered species in both surveys were the Purple-capped Fruit-Dove (Ptilinopus porphyraceus), Pohnpei Lory (Trichoglossus rubiginosus), Micronesian Starling (Aplonis opaca), and Micronesian Honeyeater (Myzomela rubratra). Among the five species endemic to Pohnpei, the Pohnpei Mountain Starling (Aplonis pelzelni) verges on extinction, with only one confirmed sighting in nearly 50 years; the Long-billed White-eye (Rukia longirostra) is vulnerable to encroaching agriculture in its preferred and limited montane habitat, where nearly 90% of the sightings were on approximately 10% of the land area, and the Pohnpei Lory (Trichoglossus rubiginosus), Pohnpei Flycatcher (Myiagra pluto), and Pohnpei Fantail (Rhipidura kubaryi) are widespread and common, but were less frequently encountered in 1994 than in 1983. The total number of birds encountered per observation station during 8-minute point counts in each of six elevation zones was 67–80% fewer in 1994 than in 1983. Encounter rates (birds/hour) were reduced by at least 50% in both uplands and lowlands in at least 14 of 29 species; none of the 29 showed an overall increase. Artifacts of sampling and sampling bias may have contributed to reduced observation rates, but anecdotal evidence suggests a decline in numbers is real and may be attributed to combined effects of habitat degradation, hunting practices, and possibly predation by introduced species. Protection of the upland forests from further degradation and more frequent monitoring to better assess population trends are recommended.
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Vol. 112 • No. 3