The seven tiny islands of Dry Tortugas are a vital layover for migrating birds traveling between South America and the United States making a staple in the Great Florida Birding Trail. Here you may find a ruby–throated hummingbird, peregrine falcon, yellow billed cuckoo and white-eyed vireo all in one day! Nearly 300 species of birds have been spotted here. Spring is the optimal time to view birds, but any season offers the chance to see something unique at this exquisite Florida Keys Birding spot.
About 80,000 nest annually on Bush Key, the only important breeding colony in the continental U.S. Outside the nesting season, they resort to the high seas and seldom approach mainland shores. Sooties are first heard in late December at night. Their numbers increase gradually until they land and begin nesting in early February. Each female produces one egg, and the male and female alternately incubate it for 29 days. They then care for the chick for 8 to 10 weeks. Their food is primarily fish and squid caught at sea surface, at times 50 miles or more away from the colony. Sooties begin to leave during June and by mid-August the colony is almost deserted. Extensive bird-banding shows that most adults spend their off -season in the eastern Caribbean, whereas young birds migrate to the eastern tropical Atlantic where they spend up to 5 years aloft off West Africa before they return to the Dry Tortugas.
About 4,500 Brown Noddies also breed on Bush Key, placing their bulky nest of seaweed and sticks in the bushes and mangrove trees. They arrive with the Sooty Terns, but tend to stay longer, sometimes as late as October. From band returns, they seem to range much less widely than Sooties, seldom leaving the Gulf-Caribbean region.
First discovered at the Dry Tortugas in 1960, a few have been found in most years since then. They appear as early as late March and as late as September. Most often they are seen perched on the north coaling dock on Garden Key, or in mangroves on Bush Key. As yet, there is no evidence that they nest in the area.
Long Key contains the only current nesting colony for the Magnificent Frigatebird in the continental U.S. They first nested in this area in 1988, and may be the same population that nested for 25 years at the Marquesas Keys until driven away by human disturbance. Long Key contains approximately 100 nests.
Present year-round in numbers up to about 40. Usually seen perched on buoys or roosting on the smaller islands. Since 1984, a few pairs have nested each winter/spring on Hospital and Middle Keys.
Scattered northbound migrants arrive as early as mid-February, and substantial migration is usual during March (especially of herons, Ibises, and some raptors and shorebirds). The Dry Tortugas kick off the northbound migration in the spring and the start of the Great Florida Birding Trail.
In June the tern colonies are in full cry and masses of juvenile Sooty Terns cover the Bush Key beaches. Most of the non-nesting species of water birds are reduced to a few individuals. Magnificent Frigatebirds, especially during windy, unsettled weather, prey to some extent on young terns. Land birds, except the resident Mourning Doves, are scarce, but spring migration persists in a very small way through much of June. By mid-July, many terns have left the nesting colonies, and the first southbound migrants appear.
Compared to the spring migration, bird migration in the fall season is more prolonged and not as obviously influenced by weather. The migration goes on from early July until late November. Large flights of raptors (especially Sharpshinned and Broad-winged Hawks, Merlins, and Peregrine Falcons) are a feature of the September-October migration, and at times these predators seem to outnumber the small land birds they prey upon.
Midwinter bird life consists mostly of a scant assortment of water birds, notably the flocks of gulls and terns that follow the fishing fleet. Land birds are limited to a few American Kestrels and Belted Kingfishers, an occasional Gray Catbird, Yellow-rumped and Palm Warblers, and Savannah Sparrows. Winter storms will sometimes blow in rare species such as snow geese, assorted ducks & shore birds. Winter is the slowest of the Florida Keys Birding seasons, but with the cold fronts, the best birding can be done since the storms send the birds off course.
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