Morphology of western and semipalmated Sandpipers 1978-2020

Increasing predation danger can select for safety-enhancing modifications to prey morphology. We document multi-decade wing lengthening of a Pacific flyway migrant, the western sandpiper (Calidris mauri), and contrast this with contemporaneous wing shortening of the closely related semipalmated sandpiper (C. pusilla) on the Atlantic flyway. We measured > 12,000 southbound western sandpipers captured 1978–2020 at a major stopover site in British Columbia. Wing length increased at 0.074 mm y-1 (SE = 0.017; p < 0.0003) for adults, and 0.087 mm y-1 (SE = 0.029; p < 0.007) for juveniles. These rates are of similarly large magnitude (4–5% overall), but opposite in direction, to the rate we previously reported for semipalmated sandpiper adults (-0.103 mm y-1). In both species, the change is specific to wings rather than being part of general body size change. We interpret both trends as responses to the ongoing strong increase of peregrine falcon (Falco peregrinus) populations since t..., Capture and morphological measurement of breeding and migrating semipalmated and western Sandpipers.
Trends and effects on annual variation were modeled with linear models.,

捕食风险的升高可驱动猎物演化出提升生存安全性的形态修饰特征。本研究记录了太平洋迁飞路线迁徙鸟类西滨鹬（Calidris mauri）数十年来的翅长增长现象，并将其与大西洋迁飞路线上近缘物种半蹼滨鹬（C. pusilla）同期出现的翅长缩短现象进行对比。我们于1978年至2020年间，在不列颠哥伦比亚省一处主要中途停歇地，对超过12000只南迁途经此地的西滨鹬进行了形态测量。成鸟翅长以每年0.074 mm的速率增长（标准误SE=0.017；p<0.0003），幼鸟翅长年增长率为0.087 mm（SE=0.029；p<0.007）。上述变化速率的绝对量级（整体达4%~5%）与我们此前报道的半蹼滨鹬成鸟变化速率（年变化量-0.103 mm）相近，但方向完全相反。两个物种的形态变化均仅局限于翅长，而非整体体型变化的一部分。我们将这两种趋势解读为对游隼（Falco peregrinus）种群自……以来持续强劲增长的响应。本数据集涵盖繁殖与迁徙阶段半蹼滨鹬、西滨鹬的捕获记录及形态测量数据。研究通过线性模型对种群趋势与年度变异的影响开展了建模分析。