Spring Migration

Spring Bird Migration Across the Florida Keys

A National Weather Service (NWS) Weather Surveillance Radar-1988 Doppler (WSR-88D) unit was constructed near Key West in the mid-1990s during the heart of the NWS "modernization and restructuring" era. The Key West WSR-88D has proven to be an extremely valuable meteorological tool, assisting weather forecasters at the NWS forecast office in Key West with discerning the location and strength of a variety of weather phenomena, including severe thunderstorms, tornadoes, waterspouts, and tropical systems. The Key West WSR-88D also can detect the location and movement of another natural phenomenon; namely, birds!

Every year during the Spring, several species of birds migrate northward through the Florida Keys from their winter habitats in the tropics. The numerous mud flats and mangrove islands surrounding the Florida Keys offer a perfect "rest stop" for some of these migrating birds. Others just pass right on over the island chain toward their summer habitats to the north. Similarly, every Autumn birds migrate southward through the Florida Keys, back to their winter habitats. Over 16 species of raptors migrate through the Keys each year, with more peregrine falcons migrating through the Keys than anywhere else in the United States!

The spring migration of land birds and shorebirds across the Gulf of Mexico begins in the first and second week of March, reaches a peak in late April/early May, and is essentially over by the third week in May.

The doppler radar image loop below shows a late night/early morning bird migration
episode on April 28, 2002. It has been estimated by ornithologists that in the dark
green radar reflectivity areas (25-30 DBZ), nearly 10,000 birds per mile are crossing over!

Radar image depicting bird migration in the florida keys.