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.

WASHINGTON – The U.S. Fish and Wildlife Service on Jan. 25 proposed listing a small freshwater fish as an endangered species and setting aside almost 300 miles of Arizona and New Mexico streams as critical habitat for the fish.

The federal government estimates it will cost more than $42 million over the next decade to help get the Mexican spotted owl off the national list of threatened species.