Bird Conservation International

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Bird Conservation International (2009), 19:323-337 Cambridge University Press
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Research Articles

Recent status and trends of the land bird avifauna on Saipan, Mariana Islands, with emphasis on the endangered Nightingale Reed-warbler Acrocephalus luscinia


a1 U.S. Geological Survey, Hawai’i Cooperative Studies Unit, P.O. Box 44, Hawaii National Park, HI 96718, U.S.A.
a2 U.S. Geological Survey, Pacific Island Ecosystems Research Center, P.O. Box 44, Hawaii National Park, HI 96718, U.S.A.
a3 U.S. Fish and Wildlife Service, Pacific Islands Office, 300 Ala Moana Boulevard, Honolulu, HI 96850, U.S.A.
a4 Commonwealth of the Northern Mariana Islands Division of Fish and Wildlife, Department of Lands and Natural Resources, P. O. Box 10007, Saipan, MP 96950.
Article author query
camp rj [PubMed]  [Google Scholar]
pratt tk [PubMed]  [Google Scholar]
marshall ap [PubMed]  [Google Scholar]
amidon f [PubMed]  [Google Scholar]
williams ll [PubMed]  [Google Scholar]


The avifauna of the Mariana Islands, an archipelago in the western Pacific, faces the threats of rapid economic development and the spread of non-native species, particularly a devastating predator, Brown Tree Snake Boiga irregularis. In this paper, we examine the status and trends of the land bird fauna of Saipan Island based on three island-wide surveys conducted in 1982, 1997, and 2007. During this period, the human population on Saipan increased more than four-fold and much of the island has been developed. The surveys employed standard point-transect methods based on Distance Sampling. Remarkably, we found nearly all species of land birds - 11 native species and three introduced species - to be common or abundant. The exception was the Micronesian Megapode Megapodius laperouse, a historically rare species that was not observed on the 2007 survey, although it does persist on Saipan and other Mariana islands. A comparison of species densities among the three surveys showed that seven species, mainly fruit and seed-eaters, had increased and three species of insectivorous birds had decreased - Rufous Fantail Rhipidura rufifrons, Nightingale Reed-warbler Acrocephalus luscinia, and Golden White-eye Cleptornis marchei. Of these three, Nightingale Reed-warbler is listed as ‘Endangered’ on the IUCN Red List and as an Endangered Species by the U.S. Fish and Wildlife Service. Reed-warbler densities on Saipan decreased by more than half between 1982 and 2007. Although point transect sampling worked well for this species, density estimates and trends assessment could be improved by reallocating sampling stations among habitats and by more frequent sampling.

(Received May 29 2008)

(Accepted February 04 2009)


c1 Author for correspondence; e-mail: