STATUS AND DEMOGRAPHIC RATES OF THE CHRISTMAS SHEARWATER PUFFINUS NATIVITATIS ON KURE ATOLL

摘要

The Christmas Shearwater Puffinus nativitatis is a small (350 g) Procellariiform seabird that nests on remote islands in the tropical and subtropical Pacific Ocean. Little is known about its demography or conservation needs. We banded and recaptured 1120 Christmas Shearwaters on Kure Atoll, the northwestern-most of the Hawaiian Islands, on 60 occasions during a 20-year period, 1995-2014. To provide demographic information that is lacking for this species, we used robust design mark-recapture models to estimate apparent annual survival, emigration, capture probabilities, and size of the study population. Annual survival of residents was 0.864 SE 0.034, which is typical for seabirds this size. The oldest known bird was at least 17 years and 1 month old. Of birds banded as chicks, the average age of first recapture was 3.9 years. Among birds captured, 11% appeared to be transients. The annual emigration rate was 0.249 SE 0.096. Thirteen shearwaters captured on Kure originally were banded on Midway Atoll; three of were captured multiple times and presumably were breeding on Kure, indicating there is exchange between the colonies on those two islands. The size of the study population averaged 358 birds, with an increasing trend and an estimate of 480 birds in the last two years. The primary reason for the population increase was eradication of Polynesian rats Rattus exulans in 1995, which has resulted in a 10-fold increase in shearwater population size since the last estimate in the 1980s. The high survival rate and increasing number of birds indicate that the Kure Christmas Shearwater population is robust.