A competition experiment between wintering Redstarts and resident Yellow Warblers in Jamaican mangrove forest
In the Caribbean, the winter influx of billions of migratory songbirds coincides with low arthropod abundances, and food shortages can limit wintering songbird populations. Despite recent progress in understanding migratory bird ecology, the question remains: how do so many ecologically similar migrant and resident species coexist during the most resource-poor time of year? All available evidence suggests that food-based competition allows coexistence of migrant and resident birds in Jamaican mangrove forests, yet no published study in any system has experimentally demonstrated that interspecific competition for food exists between migrant and resident birds. The primary objective of this study is to perform a reciprocal removal experiment to determine whether interspecific competition exists between resident Yellow Warblers (Dendroica petechia) and wintering American Redstarts (Setophaga ruticilla). This study will quantify and compare: 1) resource use (three-dimensional territory size, foraging behavior), 2) fitness indices (body mass change, spring departure date), and 3) density of Yellow Warblers and ecologically similar American Redstarts on control (unaltered) and experimental (one species removed) mangrove plots.
This project seeks to determine if food-based competition drives coexistence between resident and migrant birds, providing much needed insight into the processes that maintain migratory bird populations throughout the annual cycle. The study will maximize interactions with Jamaican and Caribbean/Hispanic students by recruiting field technicians from underrepresented groups and hiring at least one Jamaican field assistant each year. In collaboration with the University of the West Indies, two five-day field courses will be run for undergraduate- and graduate-level Jamaicans.
