RAPTOR MIGRATION ALONG THE MESOAMERICAN LAND CORRIDOR

Abstract

Each autumn (August-December), more than five million birds of prey (Order Falconiformes) migrate south from North America into Central and South America along the Mesoamerican Land Corridor, the most important raptor-migration flyway in the New World. The route, which extends for 4,000 kin from the southwestern United States, in North America, to the Choc6 region of northwestern Colombia in South America, hosts smaller numbers of northbound raptors in spring (February-May). Although reports of raptors moving along the corridor date from the 16th Century, the overall magnitude, geography, and timing of the migration only recently have come to light. The 32-species flight is dominated numerically by western North American breeding populations of Turkey Vultures (Cathartes aura) (>1.5 million individuals), together with world populations of Mississippi Kites (Ictinia mississippiensis) (>0.1 million), Broad-winged Hawks (Buteo platypterus) (>1.0 million), and Swainson's Hawks (B. swainsom) (>0.5 million). The most important concentration points along the corridor are the Gulf of Mexico coastal plain of Veracruz, Mexico, the Caribbean coastal plain of southeastern-most Costa Rica, and the canal-zone region of Panama. Migration flyways branch elsewhere along the corridor. Autumn and spring movements are greatest in late September-mid-November and in mid-March-late April, respectively. The feeding and roosting ecology of raptors using the corridor remains largely unknown. A recently initiated cooperative monitoring effort, Hawks Aloft Worldwide, has identified more than 17 incipient and active raptor-migration watchsites in the region. Together with other possible watchsites in the region, the network offers considerable potential for long-term, multi-site monitoring and study of the flight, as well as a basis for community based conservation efforts in the region. Hawkwatching in the Americas (Bildstein and KIem, Eds.) 2001. Pages 119-141.