A Massive Flock of Frigatebirds

Looking out across Sarasota Bay this morning, I saw a large flock of dark birds soaring above the main channel.  Though I initially mistook them for turkey vultures, some of the birds began to dive and I grabbed my binoculars for a closer look.  As it turned out, they were magnificent frigatebirds in a congregation far larger than I have ever encountered in the past.

After nesting in colonies on oceanic islands, primarily south of the U.S., magnificent frigatebirds move northward along the coasts of Florida during the warmer months.  There they are usually seen alone, in pairs or in small groups, often harassing gulls, terns, pelicans and ospreys to steal their catch.  These agile fliers also glean small fish, shrimp, baby sea turtles and a host of marine invertebrates from the surface of the water and are known to grab seabird nestlings from mangroves or beaches.

Should they come across a large concentration of prey (often signaled by the feeding activity of dolphins, gannets or pelicans) they may congregate in large flocks to join the feast.  I suspect this morning's sighting was such an event, drawing in hundreds of frigatebirds from the Gulf of Mexico and adjacent areas of the Bay.