Fat, weather, and date affect migratory songbirds' departure decisions, routes, and time it takes to cross the Gulf of Mexico
Fat, weather, and date affect migratory songbirds' departure decisions, routes, and time it takes to cross the Gulf of Mexico
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DOI：
10.1073/pnas.1503381112
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发表时间：
2015-11-17
影响因子：
11.1
通讯作者：
Cochran, William W.
中科院分区：
文献类型：
--
作者：
Deppe, Jill L.;Ward, Michael P.;Cochran, William W.
北美东部约三分之二的候鸟穿越墨西哥湾(GOM)，那里恶劣的天气加上没有加油或休息的机会可能是致命的。然而，由于在大范围内跟踪小动物的技术限制，在导航这些功能时做出的决定及其后果在很大程度上仍然未知。在秋季迁徙期间，我们使用自动无线电遥测技术跟踪了从阿拉巴马州沿海到尤卡坦半岛北部的三种鸣鸟(红眼翠鸟、斯文森画眉和林画眉)。在穿越类似于1000公里的开阔水域后对鸣禽进行检测，使我们能够检查影响出发决定、到达yp和穿越时间的内在变量(年龄、翼长、脂肪)和外部变量(天气、日期)。大量的脂肪储备和低湿度，表明有利的天气模式，有利于向南出发穿过墨西哥湾。在YP中检测到的个体带着大量的脂肪储备离开，并在秋季晚些时候带着有利的风离开，飞行持续时间(平均=22.4h)与风收益正相关。年龄与出发行为、到达或旅行时间无关。然而，绿蜘蛛与画眉鸟协商GOM的方式不同，包括不同的离开决定，在YP中发现的概率更低，以及更长的穿越时间。这种分化的迁徙行为可能是由画眉而不是绿鸟来防御冬季领地，以及特定物种的觅食习性造成的。脂肪储备似乎对离开和到达青年团的决定极其重要。随着GOM沿岸栖息地的退化，鸟类获取脂肪穿越墨西哥湾的能力可能会受到限制。
Approximately two thirds of migratory songbirds in eastern North America negotiate the Gulf of Mexico (GOM), where inclement weather coupled with no refueling or resting opportunities can be lethal. However, decisions made when navigating such features and their consequences remain largely unknown due to technological limitations of tracking small animals over large areas. We used automated radio telemetry to track three songbird species (Red-eyed Vireo, Swainson's Thrush, Wood Thrush) from coastal Alabama to the northern Yucatan Peninsula (YP) during fall migration. Detecting songbirds after crossing similar to 1,000 km of open water allowed us to examine intrinsic (age, wing length, fat) and extrinsic (weather, date) variables shaping departure decisions, arrival at the YP, and crossing times. Large fat reserves and low humidity, indicative of beneficial synoptic weather patterns, favored southward departure across the Gulf. Individuals detected in the YP departed with large fat reserves and later in the fall with profitable winds, and flight durations (mean = 22.4 h) were positively related to wind profit. Age was not related to departure behavior, arrival, or travel time. However, vireos negotiated the GOM differently than thrushes, including different departure decisions, lower probability of detection in the YP, and longer crossing times. Defense of winter territories by thrushes but not vireos and species-specific foraging habits may explain the divergent migratory behaviors. Fat reserves appear extremely important to departure decisions and arrival in the YP. As habitat along the GOM is degraded, birds may be limited in their ability to acquire fat to cross the Gulf.