National Geographic : 2013 Apr
Manatees 87 that allows whales to tolerate cold; in water below 68°F, they begin to weaken and die. The subspe- cies found in the United States is the Florida manatee, which disperses into coastal areas of the Atlantic Ocean and Gulf of Mexico; in win- ter, when sea temperatures drop, they congregate inland at natural springs and other sources of warmth, including power plant discharge pipes. At Kings Bay manatees have a near-perfect winter refuge. Dozens of springs scattered around the bay pump out fresh water at a con- stant 72°F year-round. The Kings Bay area is so suited to manatees that the wintering population has grown from about 30 in the 1960s to more than 600 today, mirroring the species’ increase to about 5,000 throughout Florida. On any day from November through March, Crystal River residents can quite literally walk out their doors and see dozens of manatees swimming, loafing, and sleeping in city canals like lazy dogs curled up on the lawn. “ This is basically an urbanized wildlife species that lives in our backyard, 50 feet from where we sleep,” says USGS biologist Robert Bonde, who’s Manatees swim close to the water’s surface because they are air-breathing mammals. They use their stiff facial bristles to guide food into their mouths. Mel White reported on birds of paradise in the December issue. Paul Nicklen specializes in underwater photography, often in polar regions.