Crystal River National Wildlife Refuge

Photo: David Hinkel/Flickr

A herd of endangered West Indian manatees swim in the clear waters of the Crystal River Wildlife Refuge. Established in 1983 with the mission of protecting manatees and their habitats, Crystal River is just one of hundreds of national wildlife refuges across the country.

America's first ever wildlife refuge — Florida's Pelican Island — was established on March 14, 1903, by then-President Teddy Roosevelt. Today, 562 refuges and 38 wetland management areas constitute the country's 96-million-acre refuge system.

These protected areas provide vital habitats for thousands of plants and animals, including 280 threatened or endangered species like the manatees above.

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Klamath Basin National Wildlife Refuge

Photo: Michael (a.k.a. moik)/Flickr

Klamath Basin National Wildlife Refuge Complex

The Lava Beds National Monument and Mount Shasta loom in the distance as the sun sets on the Klamath Basin National Wildlife Refuge Complex in this photo taken near the Oregon-California state line.
 
The complex is a 192,000-acre preserve that contains six distinct refuges: Bear Valley, Klamath Marsh and Upper Klamath National Wildlife Refuges in southern Oregon, and Lower Klamath, Tule Lake and Clear Lake national wildlife refuges in northern California.
 
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Great Dismal National Wildlife Refuge

Photo: Rebecca Wynn/USFWS/Flickr

Great Dismal Swamp National Wildlife Refuge
Cypress trees stand grounded in the placid waters and mist of the Great Dismal Swamp National Wildlife Refuge, a marshy region situated across southeastern Virginia and northeastern North Carolina.
 
The swamp, which only gained government protections in 1974, used to cover an estimated 1 million acres of area before 90 percent of the original swamp was destroyed by encroaching humans.
 
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Don Edwards National Wildlife Refuge

Photo: Don McCullough/Flickr

Don Edwards San Francisco Bay National Wildlife Refuge

Flocks of American avocets and marbled godwits settle along the surface of wetlands as the sun sets on the Don Edwards San Francisco Bay National Wildlife Refuge near Fremont, Calif.

Established in 1974, this 30,000-acre wetland was the first urban wildlife refuge in the country, and today it is one of six wildlife refuges in the San Francisco Bay Area.

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Catie Leary is a photo editor at Mother Nature Network. Follow her on Twitter and Google+.