Important Bird Areas

Dry Tortugas National Park

Florida

In the Gulf of Mexico in far western Monroe County, about 70 miles (112 km) west of Key West.

Composed of seven small coral and sand keys between the Gulf of Mexico and the Straits of Florida, Dry Tortugas National Park is one of Florida's treasures. The keys were discovered in 1513 by Juan Ponce de Leon and named after the abundance of sea turtles (Las Tortugas) found nesting there; the Dry was added by subsequent mariners to note the lack of fresh water. The Tortugas consist of Bush, East, Garden, Hospital, Loggerhead, Long, and Middle keys. Construction of Fort Jefferson, the largest fort along the Gulf coast, was begun on Garden Key in 1846 and abandoned in 1866 before its completion. Loggerhead Key contains a Coast Guard station and lighthouse. Hospital Key was the site of a temporary hospital during a Yellow Fever outbreak in 1867 but is now a small sand bar of only a few acres (hectares). Only Garden Key and Loggerhead Key are publicly accessible. The National Park boundary includes 100 square miles (256 square km) of ocean surrounding the keys. Commercial fishing and the use of jet skis are prohibited within the boundaries of the park.

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Ornithological Summary

The keys attract numerous Neotropical migrant species in spring and fall, and have hosted many Caribbean vagrants such as White-tailed Tropicbird, Red-footed Booby, Black Noddy, Ruddy Quail-Dove, Bahama Mockingbird, and Yellow-faced Grassquit. Over 300 native species have been seen. The keys are critical for nesting Sooty Terns and Brown Noddies, the only regular colony for either species within the continental United States. In 1988, the Marquesas Keys colony of Magnificent Frigatebirds began moving to Long Key, and by 1990, all birds were nesting at the Tortugas. In 1984, Masked Boobies began nesting on Hospital Key, and the population had increased to 19 pairs in 1998. The Tortugas are the only known nesting site of Magnificent Frigatebirds in the United States, and of Masked Boobies in the continental United States. Raptors previously were common at Loggerhead Key, preying on landbirds in the Australian-pine forest. With the trees gone, raptors and landbirds are less frequently seen. An estimated 500,000 Sooty Terns have been banded at the Tortugas since the early 1950s by the late William B. Robertson, Jr. and collaborators. Bridled Terns began nesting in the Dry Tortugas after the 2005 hurricane season destroyed the nesting substrate at Pelican Shoal, the only known previous nesting location for the species in the United States.

Conservation Issues

human disturbance, exotic plants

Based on oil present on feathers of Sooty Terns nesting at Bush Key, oil from spills in distant areas such as Louisiana and the Campeche Bank, Mexico apparently reach the Tortugas in ?biologically significant amounts? +(Robertson and Robertson 1996). ? Visitation to the islands has quadrupled since 1984, from 18,000 recreationists to 72,000, and most of this occurs between March and July. During these five months, an estimated 245 people arrive at Garden Key daily. Development of a visitor use plan is in preparation to avoid overuse of the park by tourists. ? Former low-altitude flights by U.S. Navy aircraft caused disturbance of the tern colonies.

Habitat

*mangrove forest, *coastal strand, *artificial (fort and parade grounds), tropical hammock. East, Hospital, and Middle keys are tiny sand bars; Long Key is predominantly mangrove forest. Bush Key consists of low-growing vegetation, with mangroves along parts of the shoreline. Garden Key consists of short, grassy areas with numerous ?coconut palms (Cocos nucifera), and tropical hardwoods such as gumbo-limbo, in addition to Fort Jefferson, which occupies most of the island. Until recently, Loggerhead Key consisted primarily of a dense forest of Australian-pines, but these were removed in the past few years. Loggerhead Key now is covered with cactus, agave, numerous young Casuarina, and scattered coconut palms and ?large geigertrees (Cordia sebestena).