Environmental groups are trying to halt a plan by the Bureau of Land Management to lease out more than 4,000 acres of land near the Petrified Forest National Park for oil and gas exploration.

Environmental groups will get a new chance to force the U.S. Forest Service to ban hunters from using lead ammunition in the Kaibab National Forest in a bid to protect condors.

The decision to cut more than 1,300 old-growth trees last summer in an Arizona forest has been criticized for breaking trust with the thinning project’s backers.

A federal judge has swatted the U.S. Fish and Wildlife Service for not doing enough to ensure there is a viable population of the Mexican gray wolf in Arizona and New Mexico.

It may not be surprising that an “aquatic desert” turtle faces long odds in life, but environmentalists and biologists still welcomed this week’s endangered species designation for the Sonoyta mud turtle.

A federal court has rejected a bid to declare the Sonoran Desert bald eagle an endangered species, saying the U.S. Fish and Wildlife Service acted properly when it determined the birds were no different than other bald eagles.

Two environmental groups filed a lawsuit Tuesday aimed at forcing the federal government to protect Arizona’s diminishing cactus ferruginous pygmy owl population under the Endangered Species Act.

With their natural beauty and protected environments, the Grand Canyon and other national parks in the West would seem removed from having mercury in their streams and rivers.

Despite a significant reduction in Arizona hunters using lead ammunition, an environmental group says endangered California condors in Kaibab National Forest are still dying from lead poisoning.

A federal appeals court Monday upheld the government’s decision to let a uranium mine near Grand Canyon National Park continue to operate under environmental standards now decades old.