Apparently, when a US citizen sets foot on an island rich in bird crap deposits, and the island is not claimed by anybody else, the island may, at the discretion of the president, be annexed by the USA. Further, should you be the unlucky citizen who washes ashore on this avian outhouse, you have some responsibilities, too, apparently:
The discoverer shall, as soon as practicable, give notice verified by affidavit, to the Department of State, of such discovery, occupation, and possession, describing the island, rock, or key, and the latitude and longitude thereof, as near as may be, and showing that such possession was taken in the name of the United States; and shall furnish satisfactory evidence to the State Department that such island, rock, or key was not, at the time of the discovery thereof, or of the taking possession and occupation thereof by the claimants, in the possession or occupation of any other government or of the citizens of any other government, before the same shall be considered as appertaining to the United States.Which is a bummer, because suppose I wanted to claim it for the greater glory of myself? The best I could hope for, according to §1414, would be an exclusive right to the guano concession for myself and my heirs or assigns, but I could only sell the guano to the US. Which, if your lifelong goal has been to be the robber baron governor of a colonial feces farm, would be pretty swell, I guess.
Oh, one of the islands claimed under the Guano Act is causing us a little minor border squabble with New Zealand. And they had an American queen.
Oh, well, if Peak Phosphorus really happens, we'll be glad our elder statesmen had such foresight! Or something.