Bull trout are running out of time in Montana as their traditional waters heat up, biologists say. By moving more than 100 fish to higher elevations, fisheries scientists hope to save the species by seeding a new population in waters that will stay cooler longer. Jim Mogen/USFWS hide caption

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A black-footed ferret looks out of a crate during a release of 30 of the animals at a former toxic waste site, now a wildlife refuge in suburban Denver. David Zalubowski/AP hide caption

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A pangolin is released into the wild by officials at a conservation forest in Indonesia in 2013. The animal was among 128 pangolins confiscated by customs officers from a smuggler's boat off Sumatra. Jefri Tarigan/AP hide caption

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In this image taken from a November 2012 video, Cecil the lion is shown in Hwange National Park in Zimbabwe. Paula French via AP hide caption

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Cecil the lion is shown walking in Zimbabwe's Hwange National Park in a YouTube video from July 9, 2015. Credit: Bryan Orford Bryan Orford/YouTube hide caption

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The sun sets over the Sacramento-San Joaquin River Delta near Rio Vista, Calif., in 2013. The delta is the largest West Coast estuary and a source of conflict over the state's water. Robert Galbraith /Reuters/Landov hide caption

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Numbat populations once dropped as low as 500 adults. To help save this endangered marsupial, the Perth Zoo has been rearing them in captivity for release back into the wild. But wild numbats eat only termites, which are too difficult to get in large quantities. So zoo staff have spent over a decade concocting a tasty and nutritious substitute. Helenabella via Wikimedia Commons hide caption

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An undated file photo provided by the Wisconsin Department of Natural Resources of a northern long-eared bat. A fungal disease has devastated the species, now listed as threatened. AP hide caption

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A manatee swims underwater in the springs of Crystal River, Fla. — home to a group of residents who have sued the U.S. Fish and Wildlife Service, demanding that the agency consider removing the animals from the endangered species list. Amanda Cotton/iStockphoto hide caption

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Off the coast of Southern California, a crowd watches a blue whale rise to the surface earlier this summer. A new study says the population of blue whales off the West Coast is close to historic levels. Nick Ut/AP hide caption

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Rancher Denny Johnson looks over his cattle in Joseph, Ore., in 2011. Conservationists say ranchers raising beef cattle are responsible for the decline of some wildlife. Rick Bowmer/AP hide caption

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Two Iberian lynxes at a nature reserve in northern Spain. (February 2006 file photo.) Victor Fraile /Reuters /Landov hide caption

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