Abstract

The Rusty Blackbird (Euphagus carolinus) is a widespread, uncommon migrant that has experienced heavy population declines over the last century. This species can spend over a quarter of their annual cycle on migration, so it is important to determine their habitat requirements during stopover events to inform effective conservation planning. We assessed their habitat selection at an important stopover site in northern Ohio during both fall and spring migration. Since stopover habitat selection is scale-dependent, we investigated both patch-scale (between patches) and fine-scale (within a patch) selection using radio telemetry to locate foraging and roosting flocks, and compared habitat variables between used and available points across the study site. At the patch scale, we found that birds preferred dogwood–willow swamp, low-lying forest patches, and areas of greater habitat complexity for foraging in both seasons. At the fine scale, spring migrants foraged closer to habitat edges than random, and preferred areas with more wet leaf litter and shallow water, and less grass cover. Fall migrants also preferred shallow water and leaf litter cover, and avoided areas with dense grass, forbs, and herbaceous shrub cover. By contrast, birds consistently roosted in dense stands of emergent Phragmites or Typha marsh, suggesting that the best stopover or staging sites are those with a matrix of different wetland habitats. Although the migratory range of Rusty Blackbirds is currently dominated by agricultural development, our results suggest that fragmented landscapes can still provide adequate habitat for migrants if the available land is managed for a variety of wet habitat types.

中文翻译：

---

生锈的黑鸟在中途停留期间选择栖息地复杂性更高的区域

摘要

生锈的黑鸟（Euphgus carolinus）是一个广泛而罕见的移民，上个世纪人口急剧下降。该物种可将其年度周期的四分之一以上花费在迁徙上，因此，在中途停留事件期间确定其栖息地需求以告知有效的保护规划非常重要。在秋季和春季迁徙期间，我们评估了他们在俄亥俄州北部重要中转站的栖息地选择。由于中途停留栖息地的选择取决于规模，因此我们使用无线电遥测技术研究了斑块规模（斑块之间）和精细规模（斑块内）的选择，以找到觅食和栖息群，并比较了整个栖息地和可用点之间的栖息地变量。研究地点。在斑块范围内，我们发现鸟类更喜欢山茱–柳沼泽，低洼的森林斑块，和在两个季节都需要觅食的栖息地复杂性较高的地区。在良好的规模上，春季移徙者的觅食比随机散布更靠近栖息地边缘，而首选地区的叶子凋落物和浅水较多，草皮较少。秋季移徙者也更喜欢浅水和落叶覆盖物，并避免使用草，草和草丛覆盖的地区。相比之下，鸟类始终栖息在茂密的出没林中芦苇或香蒲沼泽，表明最好的中途停留或过渡地点是那些具有不同湿地生境矩阵的地点。尽管目前生锈的黑鸟的迁徙范围主要由农业发展决定，但我们的结果表明，如果对可用土地进行多种湿地栖息地管理，那么零散的景观仍然可以为移民提供足够的栖息地。