Habitat choice shapes the spring stopover behaviour of a Nearctic-Neotropical migratory songbird

摘要

The effect of habitat choice on fuelling behaviour and the Organization of migration in birds has rarely been examined, despite the potential impact of widespread anthropogenic transformation of stopover régions. High energetic requirements in migrating birds mean that resource abundance, through its influence on fuel déposition rates (FDR), is expected to be the main déterminant of stopover and migration strategy. We examined the spring stopover of Tennessee Warblers (Oreothlypis peregrina) in northern Colombia, evaluating how diet, FDR, stopover duration, departure mass and estimated flight range varied between two commonly used stopover habitats: shade coffee plantations and pre-montane forests. Diet included insects in both habitats, but fruit was only consumed in pre-montane forest, where FDR was highest (FDR forest = 2.4% LBM/day; coffee = 0.5% LBM/day). Three différent estimates of stopover duration suggested longer stays in coffee but lengthier dura-tions did not resuit in équivalent departure mass between habitats, such that estimated flight range was twice as long for birds departing forest (2000 km) relative to coffee (1088 km). We conclude that stopover performance differed between habitats, likely infiuencing the subséquent temporal and spatial Organization of spring migration. On the basis of flight ranges, stopo-vers in shade coffee may also increase the risks of trans-Caribbean flights, suggesting a mechanism by which stopover habitat could directly influence survival. Giventhat fruit consumption in forest probably explains thèse différences, we recommend the identification of appropriate fruiting trees for Neotropical agroforestry Systems that can tolerate a variety of conditions and increase the quality of thèse anthropogenic habitats for migratory and other frugivorous birds.