May 2000
U.S. biologists travel to the Sierra La Madera in northern Sonora, Mexico, and collect part of an egg mass laid by a Tarahumara frog. With appropriate permits, they take the egg mass to Fish and Wildlife Service headquarters in Phoenix, Arizona.

May 2000
Eight days later between 850 and 900 eggs hatch.

June 2000
The tadpoles begin life in a ten-gallon aquarium. About half the water is replaced daily with tap water aged for 24 hours to let the chlorine disperse. At first the tadpoles eat chopped spinach and fish food. As they grow, their diet expands to include sliced cucumbers and zucchini, boiled egg whites, filamentous algae, and freeze-dried tubifex worms.

July 2000
The tadpoles grow rapidly. Many are moved to foster homes, including the Arizona-Sonora Desert Museum, San Bernardino National Wildlife Refuge, Buenos Aires National Wildlife Refuge, Coronado National Memorial, and Arizona State University.

August 2000
The first frogs emerge at Buenos Aires refuge 86 days after hatching. This is a surprise because biologists thought Tarahumara tadpoles took at least a year to change into frogs. Perhaps warm water and plenty of high-quality food stimulated their quick development. Only some of the tadpoles metamorphose rapidly, though. Others grow more slowly and aren’t expected to metamorphose until next spring or summer. Perhaps some tadpoles are programmed to grow more rapidly than others. Scientists have observed this adaptation in other frogs, so it may serve to improve reproductive success in a variety of environmental conditions. The young frogs vary in length from slightly less than an inch to about two inches.

October 2000
The young frogs held in aquariums are fed crickets and mealworms, while those released in semi-wild enclosures forage for themselves. Some of the outdoor frogs are now 2-1/4 inches long.

December 2000
About 350 frogs and tadpoles are still alive. Some of those in outdoor enclosures have fallen victim to giant water bugs (up to four inches long) like the one in the photo, which is devouring a metamorphosed northern casque-headed frog. Because all these frogs came from a single egg mass, biologists will need to collect more egg masses from the wild to establish a healthy breeding population. Even with these additions, the frogs will be bred selectively to increase genetic diversity. Producing egg masses and tadpoles in captivity will reduce the need to remove frogs from the wild.

Description
Small, dark spots on its body and dark crossbars on its legs distinguish this drab green-brown, medium-size (2.5-4.5 inches from nose to rear) frog. Because it lives in the water, its hind feet are extensively webbed. Both males and females call—a low grunt that lasts about half a second.

Distribution
Until the early 1980s, Tarahumara frogs ranged from the Sierra Madre Occidental northwestern Mexico (southwestern Chihuahua, eastern Sonora, and northern Sinaloa) into the Santa Rita and Atascosa-Parajarito Mountains of southernmost Arizona. The last Tarahumara frog in Arizona was spotted in 1983 in the Santa Ritas. Today they are most plentiful in the mountains of eastern Sonora (see photo).

Habitat: Streams and deep plunge pools in pine-oak woodland, thorn scrub, and tropical deciduous forest.