Status of the Mariana Crow Population on Rota, Mariana Islands

Abstract

Abstract—We conducted a survey of the endangered Mariana Crow (Corvus kubaryi) population on Rota, Commonwealth of the Northern Mariana Islands, in October-November 1995 to provide current infor-mation on numbers and distribution of this species. To allow direct com-parisons with a previous survey, we resurveyed transects established in 1982 using the same field methods and used identical analysis methods for both surveys. Several areas on Rota that lack suitable habitat and have few if any resident crows were excluded from our 6,315-ha study area. Our reanalysis of 1982 survey data for our study area gave an esti-mated population size of 1,348 crows (95 % CI = 1,136–1,564), com-pared to a 1995 estimate of 592 crows (95 % CI = 474–720). Mean num-ber of crows detected per sampling station decreased 57 % from 1.06 ± 0.09 SE in 1982 to 0.46 ± 0.05 in 1995. The apparent 56 % decrease in population size may be a result of habitat loss from development and typhoons, as well as persecution, but other factors contributing to the decline cannot be identified until more is known about the ecology and demography of the Mariana Crow population.