DAILY SURVIVAL RATE OF NESTS IS LOWER IN FRUITING THAN NON-FRUITING TREE SPECIES FOR A HAWAIIAN FOREST BIRD, THE KAUA'I 'ELEPAIO (CHASIEMPIS SCLATERI)

摘要

Nest-site characteristics are important drivers of nest success in birds, and are particularly important to understand in systems where anthropogenic factors may exacerbate their negative effects on population demographics. In Hawai'i, it is suggested that forest bird nests in fruiting tree species may have higher rates of nest predation than in non-fruiting tree species, because fruit is an important dietary component of introduced rats. I assessed the differential daily survival rate (DSR) of nests of Kaua'i 'Elepaio (Chasiempis sclateri) on Kaua'i Island, Hawai'i, in fruiting versus non-fruiting tree species using generalized linear models in program MARK. Nests were located in six fruiting tree species (n = 19) and one non-fruiting species (n = 25). Nest-tree reproductive strategy was a driver of DSR (P = - 1.15 ± 0.55 SE, 95% CI = -2.23-0.07) and DSR was lower in fruiting tree species compared to the non-fruiting species (0.975 vs. 0.992, respectively). Most nest failures were attributed to predation (9 of 10 nest failures in fruiting trees versus. 2 of 6 failures in 'ohi'a [Metrosideros polymorpha]), with the cause of other nest failures being unknown. My results support the hypothesis that tree reproductive strategy may contribute to the variability in DSR, but I did not have evidence (e.g., pictures) that the non-native black rat (Rattus rattus) was the primary predator in this study. I, therefore, discuss literature that supports this hypothesis, in addition to alternative hypotheses that may also explain my results.