Assignment Earth Video

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With sage grouse declining across the western United States, researchers try to find out if predatory ravens are responsible.

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Conservationists say the common types of these rodents, essential to healthy grasslands, are threatened by widespread poisoning by ranchers and farmers. U.S. wildlife authorities have been reluctant to give them protection under the Endangered Species Act.

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One of the planet's most endangered mammal species, Florida panthers have tripled their population to about 100 individuals during the past decade, but in a limited habitat their future survival is still in doubt.

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In Wyoming, drilling for natural gas is pumping out huge quantities of salty water from deep underground, causing serious problems for ranchers.

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U.S. wildlife authorities have reintroduced a rare sub-species of gray wolf in Arizona and New Mexico, but cattle interests, political pressures and poachers have all but doomed the recovery program.

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China's appetite for turtles threatens the survival of many species, even in the United States.

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A new Federal plan for managing Alaska's vast Tongass National Forest sparks new debate on logging.

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In Florida, power plants discharge warm water and provide manatees with essential habitats.

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With a strategy to fight a disease threatening cattle, critics say, authorities in Wyoming are unnecessarily capturing, testing and killing wild elk.

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Taking his passengers to an altitude that reveals the extent of its impact on the land, one pilot hopes to make people understand how oil and gas drilling is transforming America's western landscapes.

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In capturing carbon from the atmosphere, old-growth forests are gaining market value beyond the price of their timber.

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In Idaho, native trout suffer from disappearing water flows and competition from introduced species.

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Crystal-clear lakes near Montreal are threatened by algae blooms caused by chemical pollution from home and golf courses.

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Surrounded by downtown Chattanooga, Maclellan Island offers a safe place for herons to nest and raise their chicks.

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Initial studies show underwater habitats and species are recovering successfully in California's new marine protected areas.

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New discoveries reveal alarming increases in jellyfish in the oceans, and scientists suspect the causes could be overfishing and global warming.

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Wily and opportunistic, coyotes have moved steadily eastward and are now found almost everywhere in the United States.

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With an expanding network of acoustic receivers on the ocean floor, researchers track tagged animals and provide accurate data on life cycles and migrations of marine life.

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Architects and Conservationists in New York City seek building designs that are less hazardous to birds.

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Experts say climate change is one reason conflicts with black bears are increasing in California's Lake Tahoe area.

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Conservationists try to save an ancient species from declining habitat and growing threats from predators.

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Scientists warn that California's famous crystal-clear lake is seriously threatened by global warming.

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Successful ecotourism on the Osa peninsula raises new challenges.

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Under the protection of the Endangered Species Act, the recovery of America's national symbol is now hailed as a major success story.

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In the old-growth forests of the Pacific Northwest, northern spotted owls face an aggressive competitor and new plans to remove protection for their habitat.

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Biologists use new techniques to monitor the recovery of gray bat populations in protected cave habitats.

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In a vast region in arctic Alaska, wildlife conservationists and the U.S. government square off for a major battle over proposed oil and gas leasing.

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New York City is on the front line of a desperate war against a sneaky invader.

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Giant salamanders in the Ozark mountains are disappearing, and scientists are trying to find the cause.

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In northern California, global warming is apparently causing glaciers to grow, not shrink, on Mount Shasta.

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An ambitious plan for a giant wind farm project off the the coast of Cape Cod in Massachusetts has divided environmentalists and pitted residents against each other.

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In the southeastern U.S., land managers are using fire to restore ancient prairie habitat.

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With poachers threatening the survival of this insect-eating plant, marking them with dye helps to prosecute thieves.

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Volunteer pilots offer aerial views of environmental damage.

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New York City is pioneering the use of tidal flows to generate electric power.

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Flowing down the Mississippi, fertilizer runoff has a devastating effect in the Gulf of Mexico, creating a vast area devoid of life.

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In America's Southeast, growing population pressures are forcing states to compete for limited water supplies.

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After 150 years of mining and logging left a huge environmental disaster zone in southeastern Tennessee, massive cleanup efforts are showing positive results.

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Following years of civil war in southern Sudan, wildlife herds are thriving but facing new peacetime perils.