Data from: Migratory timing, rate, routes and wintering areas of white-crested elaenia (Elaenia albiceps chilensis), a key seed disperser for Patagonian forest regeneration

Migratory animals often play key ecological roles within the communities they visit throughout their annual journeys. As a consequence of the links between biomes mediated by migrants, changes in one biome could affect remote areas in unpredictable ways. Migratory routes and timing of most Neotropical austral migrants, which breed at south temperate latitudes of South America and overwinter closer to or within tropical latitudes of South America, have yet to be described in detail. As a result, our understanding about how these birds provide links between South American biomes is almost non-existent. White-crested Elaenia (Elaenia albiceps chilensis) is a long-distance austral migrant that breeds in the Patagonian Forest biome and overwinters in tropical South America. Because this small flycatcher plays a key role in the regeneration of this ecosystem, our objective was to describe the annual cycle of White-crested elaenias to evaluate the degree of migratory connectivity between breeding and wintering areas and therefore to determine if there are specific biomes of northern South America linked by elaenias to Patagonian forests. Fifteen individuals were successfully tracked throughout a complete migration cycle using miniature light-level geolocators. All individuals resided and moved through the same general regions. During fall (March-April-May), elaenias were located in the Caatinga and the Atlantic Forest biomes, from Rio de Janeiro to the region near Salvador da Bahia, Brazil. During winter (June-July-Aug), birds were located further inland, within the Cerrado biome. Birds used three different routes during fall migration. Our results indicate that some individuals use a direct route, flying between 500-600 km/day, crossing desert and grasslands, while others took a detour, flying 100-200 km/day through forested areas with refueling opportunities. All birds used the Yunga forest during spring migration, with ten out 15 individuals showing a clear counterclockwise loop trajectories throughout their annual cycle. None of the elaenias passed through Amazonia, traveled to western South America or crossed the Equator. Eleanias exhibited a high migratory connectivity between breeding area in Patagonian Forests and winter areas, Atlantic Forest and Cerrado. Our results suggest that Patagonian Forests could be strongly impacted by changes in those biomes or in the Yungas.

迁徙动物在其年度迁徙途中所经群落中常扮演关键生态角色。由于迁徙者介导的生物群落间联系，某一生物群落的变化可能以不可预测的方式影响偏远区域。大多数新热带区南方迁徙鸟类（于南美洲南温带纬度繁殖，在南美洲热带纬度附近或内部越冬）的迁徙路线与时间尚未得到详细描述。因此，我们对这些鸟类如何在南美洲生物群落间建立联系的认知几乎空白。白冠伊拉鹟（White-crested Elaenia，学名Elaenia albiceps chilensis）是一种长距离南方迁徙鸟类，于巴塔哥尼亚森林生物群落繁殖，在热带南美洲越冬。由于这种小型鹟类在该生态系统的再生中扮演关键角色，我们的目标是描述白冠伊拉鹟的年度周期，评估其繁殖区与越冬区间的迁徙连通性程度，进而确定南美洲北部是否存在通过伊拉鹟与巴塔哥尼亚森林相连的特定生物群落。研究通过微型光强地理定位器成功追踪了15只个体的完整迁徙周期。所有个体均栖息并穿行于相同的大致区域。秋季（3-5月）期间，伊拉鹟分布于巴西的卡廷加（Caatinga）和大西洋森林生物群落，范围从里约热内卢至巴伊亚州萨尔瓦多附近区域。冬季（6-8月）期间，鸟类分布于更内陆的塞拉多（Cerrado）生物群落中。鸟类在秋季迁徙中使用三种不同路线。结果显示，部分个体采用直达路线，每日飞行500-600公里，穿越沙漠与草原；其余个体则绕行，每日飞行100-200公里，途经有补给机会的林区。所有鸟类在春季迁徙中均途经云加森林（Yunga forest），15只个体中有10只在年度周期内呈现清晰的逆时针环形轨迹。所有伊拉鹟均未途经亚马孙地区、前往南美洲西部或穿越赤道。伊拉鹟在巴塔哥尼亚森林繁殖区与大西洋森林、塞拉多越冬区间表现出高度迁徙连通性。结果表明，巴塔哥尼亚森林可能受到这些生物群落或云加森林（Yungas）变化的强烈影响。