Estimating the functional role and quality of stopover sites around the Gulf of Mexico to inform conservation priorities for Neotropical migratory songbirds

Stopover sites where birds can refuel, rest and/or find shelter from unfavorable weather or predation are essential for successful migration, especially when faced with negotiating geographic features, like the Gulf of Mexico. Prioritization of stopover sites for conservation and management, essential for protecting migratory species, needs to consider site function and quality in combination with spatial patterns in abundance. Factors such as ecologicalcontext (e.g., proximity to barriers), birds’ physical condition and weather interact to determine the functional role of stopover sites. On the other hand, factors related to resource availability (e.g., food, shelter) influence site quality, or how wella migrant’s needs are met by a site serving a particular function. Here, we discuss two case studies examining the function and quality of stopover sites for songbirds before and after crossing the Gulf of Mexico in the fall: Fort Morgan, Alabama and the northeastern Yucatan Peninsula. We used automated radio-telemetry to estimate stopover duration, hourly activity, and departure time and direction. By combining telemetry results with data on fat reserves, mass gains, temporal patterns in capture rates and atmospheric conditions, we gained insight into the role each site plays in promoting successful migration. While some sites appear to be of low quality (Fort Morgan, Contoy Island), their ability to satisfy critical needs during migration underscores their conservation value (e.g., emergency resting opportunities on Contoy). We discuss our findings and provide guidance for empirically evaluating the functional role and quality of stopover sites for conservation prioritization