Recent status and trends of the land bird avifauna on Saipan, Mariana Islands, with emphasis on the endangered Nightingale
Reed-warbler Acrocephalus luscinia
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Resource Abstract:
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. ?? BirdLife International 2009.
Citation
Title Recent status and trends of the land bird avifauna on Saipan, Mariana Islands, with emphasis on the endangered Nightingale
Reed-warbler Acrocephalus luscinia