Diverse habitat use during two life stages of the critically endangered Bahama Oriole (Icterus northropi): community structure, foraging, and social interactions
Diverse habitat use during two life stages of the critically endangered Bahama Oriole (Icterus northropi): community structure, foraging, and social interactions
复制标题
极度濒危巴哈马黄鹂 (Icterusnorsropi) 在两个生命阶段的多样化栖息地利用：群落结构、觅食和社会互动
作者：
Melissa R Price;W. Hayes
我们防止人口减少而灭绝的能力往往取决于对因野火、伐木、农业或开发而受到干扰的栖息地的有效管理。在这些受干扰的景观中，多种栖息地类型的并置对于雏鸟和幼鸟尤其重要，这可能会在人类改变的栖息地中为附近的不同栖息地留下繁殖地，从而提供更多的觅食机会，减少竞争，并更好地保护免受捕食者的侵害。在这项研究中，我们评估了三种栖息地类型对极度濒危巴哈马黄鹂（Icterusnorsropi）两个生命阶段的重要性，巴哈马黄鹂是巴哈马安德罗斯岛特有的同人鸣禽。首先，我们确定了安德罗斯岛上三种主要植被类型中的鸟类物种组成和 I.northropi 的相对丰度：加勒比松 (Pinus caribaea) 森林、矮林 (阔叶干燥林) 和以非本地植被 (农田和开发土地) 为主的人类活动区。然后，我们比较了两个年龄段成年巴哈马金莺的觅食策略和社会互动与不同栖息地利用的关系。巴哈马金莺繁殖季节后期的鸟类调查表明，小林中鸟类种类的数量和巴哈马金莺的密度最高。在农业或住宅区从未观察到出现在矮林和松林中的一些鸟类物种，如果人类对松林和矮林的干扰增加（就像安德罗斯岛的快速发生一样），这些鸟类可能会面临危险。在繁殖季节，二年级（SY）成虫巴哈马金莺在所有植被类型中觅食，而二年级后（ASY）成虫仅在人类活动区觅食，该物种主要在引入的椰子树（Cocos nucifera）中筑巢。此外，经常观察到 SY 成鸟与 ASY 成鸟一起在人类活动区域觅食，这表明年轻的、未配对的鸟类对栖息地的利用有所不同。两个年龄段的觅食的其他方面（植被特征、食物收集行为和食物）相似。年长的巴哈马金莺在人类活动区域表现出相对较高的社会互动率（种内和种间汇集），并且与年轻人相比，赢得了更多的互动结果。我们的研究结果与其他研究结果一致，表明干燥阔叶林对于迁徙、越冬和留鸟至关重要，包括极度濒危的巴哈马黄鹂，它们在某些生命阶段似乎严重依赖这种植被类型。
Our ability to prevent extinction in declining populations often depends on effective management of habitats that are disturbed through wildfire, logging, agriculture, or development. In these disturbed landscapes, the juxtaposition of multiple habitat types can be especially important to fledglings and young birds, which may leave breeding grounds in human-altered habitat for different habitats nearby that provide increased foraging opportunities, reduced competition, and higher protection from predators. In this study, we evaluated the importance of three habitat types to two life stages of the critically endangered Bahama Oriole (Icterus northropi), a synanthropic songbird endemic to Andros, The Bahamas. First, we determined the avian species composition and relative abundance of I. northropi among three major vegetation types on Andros: Caribbean pine (Pinus caribaea) forest, coppice (broadleaf dry forest), and anthropogenic areas, dominated by nonnative vegetation (farmland and developed land). We then compared the foraging strategies and social interactions of two age classes of adult Bahama Orioles in relation to differential habitat use. Bird surveys late in the Bahama Oriole’s breeding season indicated the number of avian species and Bahama Oriole density were highest in coppice. Some bird species occurring in the coppice and pine forest were never observed in agricultural or residential areas, and may be at risk if human disturbance of pine forest and coppice increases, as is occurring at a rapid pace on Andros. During the breeding season, second-year (SY) adult Bahama Orioles foraged in all vegetation types, whereas after-second-year (ASY) adults were observed foraging only in anthropogenic areas, where the species nested largely in introduced coconut palms (Cocos nucifera). Additionally, SY adults foraging in anthropogenic areas were often observed with an ASY adult, suggesting divergent habitat use for younger, unpaired birds. Other aspects of foraging (vegetation features, food-gleaning behavior, and food items) were similar for the two age classes. Older Bahama Orioles exhibited relatively higher rates of social interactions (intraspecific and interspecific pooled) in anthropogenic areas, and won more interaction outcomes compared to younger adults. Our findings concur with those of other studies indicating dry broadleaf forest is vitally important to migrating, wintering, and resident birds, including the critically endangered Bahama Oriole, which appears to depend heavily on this vegetation type during certain life stages.