Birds of Karkar and Bagabag islands, New Guinea. Bulletin of the AMNH ; v. 164, article 4

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New York : American Museum of Natural History
"We analyze the avifaunas of Karkar and Bagabag, two Quaternary volcanic islands off the northeast coast of New Guinea. Our discussion is based on collections and observations of birds, and incidental collections of mammals, made on these islands in 1969. The first part of our discussion considers general features of interest in the avifaunas, and the second part consists of individual species accounts. Most bats and nonvolant mammals of Karkar and Bagabag occur in the adjacent New Guinea lowlands and on other nearby islands. However, the bat Pteropus tonganus is otherwise absent from the New Guinea and Bismarck regions, though widespread on more remote Pacific archipelagoes from the New Hebrides eastward. As judged by distributions and subspecific affinities, most bird species have been derived from New Guinea, except for seven species (including four small-island specialists or 'supertramps') derived from the Bismarck Archipelago. There are no endemic forms. Most of the bird species are superior overwater colonists shared with other nearby islands. Altitudinal ranges are plotted for all resident species of Karkar. Species number decreases regularly with altitude. Altitudinal limits of different species show little tendency to coincide: i.e., there is little altitudinal zonation of the avifauna. Eight species on Karkar are confined to the mountains. Comparison of the resident avifauna of Karkar in 1969 with that determined by Meek's collectors in 1914 yields a minimum turnover rate of 0.34 percent of Karkar's bird populations turning over (immigrating or going extinct) per year. Karkar and Bagabag support only a fraction of the bird species found in similar habitats on New Guinea. Total population densities on Karkar and Bagabag are considerably below those on New Guinea. Due to this reduction in interspecific competition, half of the species on Karkar undergo niche shifts--i.e., occupy broader altitudinal, habitat, or vertical ranges or live at higher densities than do the source populations on New Guinea. Study of primary molt and gonad condition of collected specimens and nest records permit tentative conclusions about reproductive cycles for most species. Few species breed in the dry season except for frugivores. Some species, especially wide-ranging colonizers, increase their reproductive potential by molt-breeding overlap, adventitious breeding, or both. Our accounts of individual species report measurements and weights of collected specimens, color of soft parts, local names, breeding and molt data, stomach contents, taxonomic conclusions, and voice and other field observations"--P. 471.
p. 469-531 : ill., map ; 26 cm.
Includes bibliographical references (p. 528-531).