Thursday, March 3, 2011

Dry Tortugas

The Dry Tortugas are a National Park about 70 miles west of Key West.  The major island contains Fort Jefferson, which just about fills the whole atoll.  This fort is said to be the second largest brick edifice in the world, after the Great Wall of China.  Built by the North during the Civil War, northern prisoners were kept there.  Perhaps the most famous inmate was Samuel Mudd, who mended Lincoln-assassin John Booth's broken leg.
Because of its breeding colony of seabirds, the island adjacent to Fort Jefferson is of interest to birders.  In February, birds were just beginning to return to breed.  Many of the more uncommon species had yet to appear.  The National Park Service does not allow visitors close access to the breeding colony, but I was able to get a couple of photos of the two common seabirds in the area.
The photo above is of a Sooty Tern.  The birds below are Brown Noddies, which are also terns.  Both species are pantropical, which means they are found in many tropical oceans.  Indeed, I listed the Sooty Tern for the first time in Australia and the Brown Noddy in the Galapagos.  In the United States, Sooty Terns breed on the Dry Tortugas, on islands off the Louisiana coast, and in the Hawaiian Islands.  They only come to land to breed, and are known to stay in the air for several years between hatching and first nesting.  They are prone to be blown to strange places by hurricanes, reaching such far off locations such as New York and Wisconsin.
Although the Brown Noddy is found in many tropical oceans and breeds elsewhere in the Caribbean, the Dry Tortugas is the only continental United States breeding location.  Colonies also breed in Hawaii, Puerto Rico, and the U. S. Virgin Islands. They lay but one egg, and the young take several years to mature.  Their name is derived from head bobbing that occurs during courtship displays.

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