Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 29, Number 9;   September, 2002

Colorado Division of Wildlife

PRESS RELEASE, July 31, 2002

Hatchery-Reared Boreal Toads Released

In an attempt to help re-establish populations of the endangered boreal toad, the Colorado Division of Wildlife (DOW) has released 1,100 captive-reared tadpoles into Rocky Mountain National Park. The release marks the first time boreal toad tadpoles produced in a new captive-rearing program have been released into the wild.

The DOW and the U.S. Geological Survey released the toads June 13 in the Kettle Tarn area of the park, along the north fork of the Big Thompson River. The area was where the breeding pair of boreal toads from which the tadpoles came was captured.

The released tadpoles will be monitored by the U.S. Geological Survey.

Boreal toads (Bufo boreas boreas) have been an endangered species in Colorado since 1993, and have been federally listed as a "warranted but precluded" species under the Endangered Species Act. Their numbers have decline dramatically over the past two decades, and the toads appeared to be on their way to extinction by the mid-1980s. Surveys indicated that as much as 85 percent of Colorado's boreal toad populations had disappeared.

While biologists aren't entirely certain what caused the toads' demise, they believe a little-known fungus, Batrachochytrium dendrobatitis or frog chytrid, is to blame. Most other chytrid species live on dead plant material or on insects, but the frog chytrid attacks the skin on amphibians.

There are approximately 50 known breeding populations of boreal toads in the southern Rocky Mountains; all but one of those populations is in Colorado. Most of the populations are very small. DOW biologists continue to monitor breeding sites to determine population trends for the boreal toad.

The DOW had been taking steps to ensure the toads' survival and has been rearing them in captivity since 2000. A breeding population of more than 1,000 toads was established at the DOW's John W. Mumma Native Aquatic Species Restoration Facility in Alamosa in the San Luis Valley. The breeding toads were captured from 18 different sites to ensure genetic diversity. DOW biologists are working to identify those sites that are chytrid-free. Eventually, DOW biologists hope to use these areas as release sites for captive-reared boreal toads and tadpoles in efforts to establish new boreal toad populations.

The Mumma facility is the only state-run facility in the nation specifically designed and built to raise threatened and endangered fish, amphibians and mollusk species. Other species besides the boreal toad raised there are the northern redbelly dace, the razorback sucker, the Colorado pikeminnow, the bonytail chub and the Rio Grande sucker.

The boreal toad is one of 17 species of amphibians native to Colorado. The toads, which grow to a maximum length of 4 inches, live almost exclusively above 8,000 feet and can be found up to 12,000 feet. They live in forested areas and need shallow standing water for breeding.

In the southern Rocky Mountains, they have dark, brown-black bumpy skin and usually have a white or cream-colored stripe down their back.