AZ Press: Zoo-bred frogs released near Payson

[Herp News]

ARIZONA REPUBLIC (Phoenix) 15 September 09 Zoo-bred frogs released near Payson - Threatened species will be monitored in new habitat (Shaun McKinnon)
Biologists have released nearly 1,400 Chiricahua leopard frogs into riparian habitat outside Payson, the latest step - or hop - toward rescuing an ailing native species.
The frogs, actually a mix of tadpoles and small froglets, hatched and developed in a roomful of closely watched tanks at the Phoenix Zoo. Spending their early days in a safe environment, rather than in the wild, where they can become a food source, increases their chances of survival.
The goal is to help the frogs establish a breeding population in their new homes, in this case a series of ponds along Ellison Creek in the Tonto National Forest.
State and federal biologists, who released the amphibians last week, will continue to monitor the frogs as they adapt to their new surroundings.
"We don't really know how the survivorship of these captive-reared animals compares to wild animals," said Jim Rorabaugh, a biologist for the U.S. Fish and Wildlife Service. "We know usually that if we've selected the site correctly, we will establish a breeding population there almost every time."
The captive-breeding and repopulation program is part of the recovery plan established for the frog when it was listed as a threatened species. The fist-size frog once thrived in Arizona and New Mexico, but it has fallen victim to shrinking riparian habitat and non-native predators.
The Phoenix Zoo began breeding leopard frogs more than a decade ago, working with the federal wildlife agency, the Arizona Department of Game and Fish, and national-forest managers.
The first of the spring season's egg masses arrived at the zoo in May. As they hatched, the future frogs were dispersed among glass tanks, where they underwent metamorphosis over the summer.
For the first time, zoo biologists varied the water temperature of the tanks to see how the tadpoles and froglets responded to different conditions. Tara Sprankle, the zoo's conservation manager, said they anticipated that the frogs in warmer water would grow fastest and those in room-temperature water would grow slowest.
The results befitted Goldilocks: The fastest-growing group swam in neither the warmest nor the coolest water, but in temperatures somewhere in the middle. Biologists are now comparing the size of the froglets at metamorphosis to see which temperature produced the largest specimens.
"Ideally we want to release the largest froglets possible to increase their chances of survival." Sprankle said.
The frogs were released on areas selected using several criteria, Rorabaugh said: the presence of water year-round, the lack of non-native predators such as bullfrogs and fish, and the absence of a fungal skin disease that has infected frogs elsewhere in Arizona and around the world.
Timing is also important, he said. Release them too early and monsoon storms could disrupt the sites; release them too late and they might not have enough time to adapt to their new home before they go dormant for the winter.
The final count when the 13-member team released the frogs was 1,393, Sprankle said.
"Getting to take the little frogs back to the wild and let them go is the best part of my job," she said. "I look forward to the day when the frogs are doing so well on their own that I get put out of business. Of course, there will always be another species that needs help, so my work may never be completely done."
http://www.azcentral.com/12news/news...gs0915-CP.html