<p>A least tern checks on its rock-colored eggs on a <a id="vn26" title="Gulfport, Mississippi (map)" href="http://maps.nationalgeographic.com/map-machine#s=r&amp;c=30.288717426233095, -89.04075622558595&amp;z=10">Gulfport, Mississippi (map)</a>, beach on Saturday. The Mississippi coast is home to one of the largest nesting colonies of least terns in the United States, according to the <a id="gk_3" title="National Audubon Society" href="http://www.audubon.org/">National Audubon Society</a>. <br><br> But as oil from <a id="di5c" title="the Deepwater Horizon spill moves closer to shore" href="http://news.nationalgeographic.com/news/2010/05/photogalleries/100504-gulf-of-mexico-oil-spill-environment-nation-pictures/#gulf-oil-spill-satellite-picture-timeline-april-21_19871_600x450.jpg">the <em>Deepwater Horizon</em> spill in the Gulf of Mexico moves closer to shore</a>, the migratory birds are among up to 400 coastal species that could be affected, biologists say. Least terns are likely to come in direct contact with the slick, because they fish for food along the beach, said Lee Schoen, curator of birds at the <a id="awy5" title="Audubon Zoo" href="http://www.auduboninstitute.org/visit/zoo">Audubon Zoo</a> in New Orleans. <br><br> "The turns are right there on the beach, and they nest on the shores of these barriers islands. Along with all of the other [potential dangers], they're going to have nests getting oil in them," Schoen said. (See <a id="prhu" title="shorebird pictures" href="http://animals.nationalgeographic.com/animals/photos/shorebird-photos/#american-avocet-pair-nest_12933_600x450.jpg">shorebird pictures</a>.)<br><br><em>—Craig Guillot</em></p>

Least Terns

A least tern checks on its rock-colored eggs on a Gulfport, Mississippi (map), beach on Saturday. The Mississippi coast is home to one of the largest nesting colonies of least terns in the United States, according to the National Audubon Society.

But as oil from the Deepwater Horizon spill in the Gulf of Mexico moves closer to shore, the migratory birds are among up to 400 coastal species that could be affected, biologists say. Least terns are likely to come in direct contact with the slick, because they fish for food along the beach, said Lee Schoen, curator of birds at the Audubon Zoo in New Orleans.

"The turns are right there on the beach, and they nest on the shores of these barriers islands. Along with all of the other [potential dangers], they're going to have nests getting oil in them," Schoen said. (See shorebird pictures.)

—Craig Guillot

Photograph by Dave Martin, AP

Gulf Oil Spill Pictures: Ten Animals at Risk

The Gulf of Mexico oil spill is poised to do widespread damage to coastal wildlife, from pelicans on the shore to dolphins at sea.

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