SummaryThe 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 seedeaters, 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.

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.Allen Press is collaborating with JSTOR to digitize, preserve and extend access to The Journal of Wildlife Management.Abstract: The Hawaiian goose or nene (Branta sandvicensis) restoration program, initiated in 1949, and with the release of about 2,150 captive-bred birds, has not resulted in a self-sustaining wild population. Results from a capture-recapture analysis indicate that 3 factors affected mortality rates: the year of release, age-class and method of release. Estimated annual mortality ranged from 0 to 87%. Comparisons between sites revealed the unsuitability of some upland sanctuaries as release sites. Hawaiian geese released in the 1960s survived at levels comparable to other wild, healthy goose populations (i.e., between 5 and 16% mortality) until the drought years 1976-83. During this period the majority of captive-reared and released Hawaiian geese (about 1,200) perished. Previously released adults generally survived better than newly released goslings. Birds made temporarily flightless initially to contain them in release pens survived less well than those released before fledging. The upland Hawaiian geese that did survive, did so at areas other than their release site; if they emigrated they survived better, especially during drought years. In all cases movement was away from habitats with dry upper montane-volcanic scrubland to areas with managed grasslands, managed ranchland, or supplemental feed and water. More movements occurred in drought years. Once the geese moved they rarely returned to their release sites. The lowest mortality and highest nest success rates were achieved by geese living at Hawaii Volcanoes and Haleakala National Parks. Hawaiian geese in these areas survived at levels similar to other nonhunted goose populations.

Summary Insular species, particularly birds, experience high levels of speciation and endemism. Similarly, island birds experience extreme levels of extinction. Based on a 2012 taxonomic assessment, historically there were four reed-warbler species in the Mariana Islands, the Guam Reed-warbler Acrocephalus luscinia (Guam), the Nightingale Reed-warbler Acrocephalus hiwae (Saipan and Alamagan), the Aguijuan Reed-warbler A. nijoi (Aguiguan or Aguijuan), and the Pagan Reed-warbler A. yamashinae (Pagan). Between 2008 and 2010 we surveyed for three of these species on Alamagan, Aguiguan, and Pagan. Our results indicate that reed-warblers are extinct on Aguiguan, likely extinct on Pagan, and only the Nightingale Reed-warbler on Alamagan and Saipan remains. We estimated the global population at between 1,019 and 6,356 birds (95% CI; mean estimate 3,688), which has declined by more than 1,000 birds since the first quantitative surveys were conducted in 1982, i.e. a 24% decline in 28 years. Camp et al. (2009) describe the status of the Nightingale Reed-warbler on Saipan, which has also declined. We estimated the Alamagan population to be between 428 and 1,762 birds in 2010 (mean estimate 946). Thus, the Alamagan population is ~25 % of the global population, and it has declined slightly since 2000. This decline was not significant but is concerning, especially given a similar decline on Saipan. Restoration and protection of tall-stature native and secondary forest could benefit the Alamagan population, as would similar conservation on Saipan that includes wetland habitat. After suitable restoration of forest and wetland habitats on Aguiguan, Guam and Pagan, individuals from Alamagan and Saipan could serve as founder populations. Careful consideration of the extent and habitat preference of individuals translocated to Tinian, where an unknown reed-warbler species previously occurred, is warranted.

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