One of the first naval wireless stations was built at the fort early in the 1900’s, and, during World War I, Tortugas was equipped for a seaplane base. But as the military moved out again, fire and storms and salvagers took their toll, leaving the “Gibraltar of the Gulf” the vast ruin that it is today. _Tortugas Birds_ One of our great national wildlife spectacles occurs each year between May and September, when the sooty terns assemble on Bush Key for their nesting season. The terns come from the Caribbean Sea and west-central Atlantic Ocean and land by the thousands on Bush Key. Their nests are no more than depressions in the warm sand. The parents take turns shading their single egg from the sun. When the young are strong enough for continuous flight, the colony again heads southeastward to tropical seas. The presence of these tropical oceanic birds at Tortugas was recorded by Ponce de León (1513), Capt. John Hawkins (1565), John James Audubon (1832), and Louis Agassiz (1858). During the early 1900’s, commercial egg-raiding reduced the colony to only 4,000 birds, but careful protection restored the strength of the colony; 120,000 birds are now recorded at the rookery. Several hundred noddy terns, similar to the sooty in habit and size, nest in the low shrubbery of Bush Key. The great man-o’-war, or frigate, bird congregates here during the tern season to enjoy an easy existence on minnows pirated from the terns. With a wingspread of about 7 feet, the frigate is one of the most graceful of the soaring birds. Though rarely seen elsewhere in any number, as many as 200 glide endlessly on the thermal updrafts above the fort. Blue-faced and brown boobies of the West Indies are year-round residents of Tortugas. Each summer a colony of a few hundred roseate terns, which normally inhabit the Atlantic seaboard north of Cape Hatteras, nest on Long Key. In season, a continuous procession of songbirds and other migrants fly over or drop off for rest at the islands, which lie across one of the principal flyways from the United States to Cuba and South America. Familiar gulls and terns of the north, as well as many migratory shore birds, spend the winter at Tortugas. [Illustration: _Ruins of the officers’ quarters._] [Illustration: _Dr. Samuel A. Mudd._] [Illustration: _The sooty tern shades its eggs from the hot sun._] _Plant and Animal Life_ The warm Gulf Stream waters support great reefs of coral and “forests” of marine plants, which in turn provide refuge for the myriad forms of animal life in nature’s aquarium. The visitor who is equipped with a glass-bottomed bucket or box can enjoy the sight of brilliant tropical fish and crustaceans in the crystal-clear waters of their native environment. Sport fishing is permitted in accordance with regulations, which may be obtained from the superintendent.