Jennifer A. Chin (cswallow) wrote,
Jennifer A. Chin

Dry Tortugas NP, Day 2: Wind, and where the terns go

On Tuesday after lunch we look at the data logger information, and find that the birds meander south-east after leaving Bush Key island, down to West Africa. Then in December, they turn tail and fly all the way back in just 12 days.

Outside the wind is picking up to 37 knots - gale force, says John, one of the NPS boat crew members. The wind. It becomes a fact of life for us, like the salted thickness of our hair, the brittle surface of our skin, the constant call of terns in the sky. It dampens us all a little bit, takes the edge off of our spirits. The terns conserve energy and hunker down on their nests. Nobody wants to be out in it. Yet every yin has its yang. Because of the wind, there are no tourist boats that run all week, and we have this strange, lovely island all to ourselves for four days. And, points out one of the NPS staff, at least it isn't humid and sweltering. 

In the colony, the birds dig their nests as shallow depressions in the sand. Their eggs are barely larger than a golf-ball, speckled like beach coral. With sharp beaks, sooty terns tuck their single egg underneath themselves, and fluff their feathers forward to keep it warm. When the chick hatches, it is an ash-colored ball of spiky fluff, with tiny useless wings. They are beautiful birds. It is so important for only a couple of people to enter the colony at a time - these people must be nimble-footed, eagle-eyed, and also mentally calm. There are eggs everywhere, and they blend in with the sand. The colony nests under thick underbrush to protect them from the resident Kestrel, but they are prey still to the pale yellow ghost crabs and aggressive gulls that eat both eggs and chicks.

Fortunately, the sooty tern is one of the most common seabirds. This colony alone has 80,000 birds - but it is the only colony in the United States. All of them next on one island in the Dry Tortugas. Seabird conservation is a guessing game: one bird is so small and most fly quickly and very far, so we know almost nothing about them.  The data logger information is illuminating indeed.

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