Before the Chiricahua leopard frog earned a spot on the federal government's endangered species list in 2002, the amphibians thrived in the streams and ponds of Arizona and New Mexico.
But scientists saved the species from extinction.
Thursday, biologists released hundreds of adult frogs and tadpoles back into their endemic riparian environments of Tonto National Forest in an area called Gentry Creek near Payson.
"Until the 1970s, Chiricahua leopard frogs lived in ponds and creeks across central and southeastern Arizona, but we've seen real population declines since then," said Mike Sredl, an Arizona Game and Fish Department herpetologist.
"Now, you can only find them in a few waterways that don't have many non-native predators. Bullfrogs, crayfish and other non-native fish are a real problem for Chiricahua leopard frogs."
That's why the federal government, state agencies and local groups stepped in. Scientists from the Phoenix Zoo studied the frogs and cared for the eggs until they reached adulthood.
Before reintroduction into the wild, the frogs received a fungicide treatment to prevent the spread of an amphibian-killing disease called chytridiomycosis.
During the three-hour ride from the Valley to Tonto National Forest, the Arizona Game and Fish Department placed the frogs in coolers to prevent their overheating; biologists also placed small aerators in some of the containers that held the tadpoles to keep the water oxygenated.
Before the frogs and tadpoles were released, scientists prepared their riparian habitat, providing the amphibians with a better chance of survival.
According to the U.S. Fish and Wildlife Service, the frog was historically found in 212 sites in Arizona, 170 sites in New Mexico, and a dozen sites in Mexico. Since 1995, frog populations have declined to only 52 Arizona and 27 New Mexico sites.
Disease, habitat-loss, Arizona's drought and other problems have exacerbated the destruction of this species, but biologists hope that Thursday's release will help frog populations recover.
To begin the process, eggs were collected in compromised habitats where the frogs would have a slim survival rate.
"We're optimistic that these types of cooperative recovery efforts will slow and eventually reverse the decline of the Chiricahua leopard frog," said Jeff Servoss, a U.S. Fish and Wildlife Service biologist. "We are equally excited about the cooperative spirit that we have received."
The plan includes the subsequent release of frogs through October.