Understanding how migratory animals respond to spatial and temporal variation in habitat phenology is critical for identifying selection pressures and tradeoffs at different life history stages. We examined the influence of breeding habitat phenology on life history timing of the eastern willet (Tringa semipalmata semipalmata) across a latitudinal gradient of breeding sites on the east coast of North America. To describe migration and life history timing, we deployed light-level geolocators on willets at breeding sites in New Jersey, Massachusetts and Maine, USA and evaluated additional data on life history timing and migratory connectivity from previous studies, eBird and band recoveries. Willets from Nova Scotia to Georgia winter exclusively on the Atlantic coast of northern South America and share common stopover sites. The timing of wintering site departure, breeding site arrival, nesting and southbound departure was later for birds breeding at higher latitudes while the duration of all life phases was similar across sites. Regardless of latitude, nesting corresponded with a consistent stage of seasonal salt marsh biomass accumulation and with peak spring temperature acceleration (GDD jerk). Temperature acceleration and salt marsh biomass were closely correlated with each other across the 11° latitudinal gradient we examined and with the timing of nest initiation across the northern 6° of this gradient. For this northern 6° of latitude, these results suggest that the timing of migration and breeding events in the annual cycle of eastern willets is constrained by a phenological “green wave” of spring salt marsh productivity at breeding sites.

了解迁徙动物如何应对栖息地物候的时空变化对于确定不同生活史阶段的选择压力和权衡至关重要。我们研究了北美东海岸繁殖地的纬度梯度上的繁殖栖息地物候学对东部威柳（ Tringa semipalmata semipalmata ）生活史时间的影响。为了描述迁徙和生活史时间，我们在美国新泽西州、马萨诸塞州和缅因州的繁殖地的威柳上部署了轻型地理定位器，并评估了来自先前研究、电子鸟和带恢复的有关生活史时间和迁徙连接性的额外数据。从新斯科舍省到佐治亚州的威鹬只在南美洲北部的大西洋沿岸过冬，并有共同的中途停留地。对于高纬度地区的鸟类来说，越冬地出发、到达繁殖地、筑巢和南下出发的时间较晚，而不同地点的所有生命阶段的持续时间相似。无论纬度如何，筑巢都与季节性盐沼生物量积累的一致阶段和春季峰值温度加速（GDD 急动）相对应。在我们研究的 11° 纬度梯度上，温度加速和盐沼生物量彼此密切相关，并且与该梯度以北 6° 上的巢穴起始时间密切相关。对于北纬 6°，这些结果表明，东柳每年周期中的迁徙和繁殖事件的时间受到繁殖地春季盐沼生产力的物候“绿波”的限制。