科研之友
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摘要
Forests of the Hawaiian archipelago are a global hotspot for conserving avian diversity and contain among the world's most imperiled species. Demographic studies are necessary to determine primary causes of Hawaiian forest bird population declines. We conducted research on the nesting success of multiple bird families on the island of Kauai, allowing us to investigate the importance of factors related to breeding biology on forest bird declines at a community scale. Our study included two Hawaiian honeycreepers, anianiau Magumma parva and apapane Himatione sanguinea, a native monarch flycatcher, Kauai elepaio Chasiempis sclateri, and one introduced species, Japanese white-eye Zosterops japonicus. Data from 123 nests showed that nesting success +/- SE, estimated using program MARK, was low for apapane (0.23 +/- 0.10), but did not vary substantially among our other study species (anianiau = 0.56 +/- 0.09, Kauai elepaio = 0.63 +/- 0.08, Japanese white-eye = 0.52 +/- 0.11). Causes of nest loss for 51 nest failures included nest predation (43%), unknown (25%), empty after termination with no signs of nest predation (e.g. eggshell or chick remains in nest, disheveled nest) (24%), and abandoned clutch or brood (4% each). Kauai elepaio suffered more than twice as many nest losses to predation compared to our other study species, but also had the highest nesting success; and, apapane suffered least to nest predation, but had the lowest nesting success. Further, rates of nesting success derived in our study were relatively high compared to multi-species studies in mainland tropics. Therefore, although nest predation accounted for the greatest proportion of nest failures, it may not be a cause of forest bird population declines in our system. We suggest that future demographic studies focus on post-fledgling, juvenile, and adult survival, in addition to the importance of double-brooding and renesting attempts on annual reproductive success.
- 出版日期2016-3
