A trail camera captures the mountain lion during its journey from west to east. Courtesy of Connecticut Dept. of Energy & Environmental Protection hide caption

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As warming temperatures drive polar bears south, they're starting to mix with brown bears much the way they did thousands of years ago. iStockphoto.com hide caption

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This is what a woolly mammoth looked like — the 10,000-year-old head was found, preserved in ice in the Siberian tundra near the Russian town of Yakutsk in this photo from 2003. Naoki Suzuki/AP hide caption

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Kittiwake young ingest food regurgitated by their parents. USGS hide caption

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Mark W. Moffett

Bob Ingersoll (left) spent nine years with Nim, the subject of an experiment to see if apes could communicate with humans using sign language. Ingersoll is now the president of Mindy's Memory Primate Sanctuary. Roadside Attractions hide caption

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A sea lion eats a salmon in the Columbia River in Washington in 2008. A bill has recently been introduced in Congress to reauthorize the killing of sea lions that are eating the endangered salmon. Don Ryan/AP hide caption

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