Competition

Photos by Laura Gooch and Tim Lenz.

Dietary competition in resident and migratory songbirds

Each winter billions of migratory birds travel to the tropics, dramatically increasing the number of birds in habitats formerly occupied by year-round residents. In the Caribbean, the annual peak in numbers of insectivorous birds coincides with the dry season, the time when their arthropod prey are least abundant. In collaboration with Luke Powell, Rob Fleischer, and Pete Marra at the Smithsonian Conservation Biology Institute, we are investigating if ecologically similar migrant and resident bird species are able to coexist via partitioning of food resources. We are using next-generation sequencing of the feces of resident birds (such as the yellow warbler, left) and migrant birds (such as the American redstart, above right) in Jamaica to obtain DNA sequences of diet items. We are then matching the sequences to a comprehensive database of DNA 'barcode' sequences for Jamaican arthropods, which we are building in collaboration with Delano Lewis at Northern Caribbean University. This is a critical step towards understanding the importance of interspecific competition as a mechanism influencing population processes in these birds. This is especially timely, because of the ongoing decline in numbers of many migrant species.