Endangered Miss. frogs get a break in the weather
Posted: Wednesday, October 15, 2008 9:08 pm
By J. McCONNAUGHEY
Associated Press Writer
NEW ORLEANS (AP) — Pick up a Mississippi gopher frog and it covers its eyes with its forefeet, like someone afraid to see what’s coming next. And for at least a decade, it’s had a good reason not to look.
This year, for a change, nature gave a bit of a break to one of the nation’s most endangered species.
The frogs breed only in ponds so shallow they dry up in summer. Hot, dry springs have stranded tadpoles every year since 1998, when 161 froglets hopped out of Glen’s Pond in coastal Harrison County, Miss.
The pond held water longer this year. And 181 tadpoles survived a deadly parasite, made it through metamorphosis and headed into the surrounding DeSoto National Forest.
Biologists saved seven generations. They wash some eggs in well water, apparently removing the parasite, hatch them in a lab and put the tadpoles in screen-covered outdoor tanks.
Scientists believe fewer than 100 mature adults live in the wild. Five zoos — in New Orleans, Memphis, Detroit, Miami and Omaha, Neb. — have another 75 frogs.
“Our efforts have managed to stave off likely extinction but there’s a long way to go,” said Joe Pechmann, an associate professor of biology at Western Carolina University who has studied the frogs since 2002.
Mississippi gopher frogs once lived in longleaf pine forests from western Alabama to southeast Louisiana. Timbering all but eradicated those forests.
Scientists estimate the population from those breeding each year. This year, 50 came to Glen’s Pond. Thirty of them were tank-raised; the other 20 had hatched in 2001 and 1998.
Other counts are next to impossible: the frogs live underground, in stump holes and burrows dug by other animals.
They have other oddities. Their breeding call sounds like snoring. And, rather than the smooth backs of many frogs, theirs have bumps which secrete a bitter, milky fluid. Pechmann thinks their “see-no-evil” pose may protect frogs’ faces until predators taste the liquid and drops them.
Mississippi gopher frogs face dangers common to all amphibians — predators that eat most of their young, human destruction and pollution of their habitat, and parasites more devastating to amphibians than the Great Plague was to humans.
Scientists estimate that the world has lost up to 170 frog species just in the last decade, and another 1,900 are threatened.
Until 2004, when a much smaller colony was found and a third was created, Glen’s Pond was the Mississippi gopher frogs’ only known breeding spot.
“People look at temporary ponds and they think there’s something wrong with them,” either filling them in or digging them deeper for fish ponds or cattle watering holes, Pechmann said. “But the reality is, there’s a lot of species such as gopher frogs that depend on temporary ponds; they can’t live anywhere else.”
The ponds are on ridges, prime development targets. Scientists worry that a housing development near Glen’s Pond could keep the U.S. Forest Service from making controlled burns needed by the forest and its animals. But Nathan Watson, senior vice president of development for Tradition Properties Inc., said it is making firebreaks and other provisions to let the burns continue.
No tadpoles survived drought in 1999 or 2000. In 2001, authorities called the National Guard. Crews trucked in water and dug a well from which water was pumped into the pond.
Pechmann first set up tanks in 2002. Since then, scientists have released about 2,000 tank-raised froglets at Glen’s Pond and another 3,000 or so at a colony scientists are starting. It’s on land owned by The Nature Conservancy, which also owns a 292-tract including the second natural colony.
Researchers used the pump at Glen’s Pond in 2005 but only 42 frogs emerged, Pechmann said.
The species’ first captive breeding was in March, when in vitro fertilization produced 93 tadpoles at the Memphis Zoo. They all died, apparently from the parasite that kills tadpoles in Glen’s Pond. A second lab-fertilized group hatched recently, said Andy Kouba, head of the Memphis zoo’s research department.
“We’ll probably end up trying to breed them several more times this fall,” he said.
Twenty-one egg masses were laid in Glen’s Pond this year, and one each in the other two, biologist Mike Sisson said.
Each year’s froglets get marked. This year, 480 are in large individual enclosures to learn whether new colonies could make it in less than ideal habitat.
The Audubon Zoo in New Orleans got 36 tadpoles. Sixteen survived.
“They were smaller than a pea when we put them in the tanks,” said Nick Hanna, assistant curator for reptiles and amphibians.
The inch-long froglets may grow to 3 1/2 inches.
Any chance of breeding is years away. Males may mature sexually in less than a year, but it can take up to four years for females to become fertile.
The wild froglets alone would nearly triple the wild population if all of them survived.
That won’t happen.
“Those little frogs are snack food or finger food for a lot of things in the woods,” Sisson said. “The vast majority … will not make it to adult frog. That’s the nature of the business if you’re an amphibian.”
On the Net:
Association of Zoos and Aquariums publication on gopher frogs: http://tinyurl.com/5xh6w9
Audubon Zoo: http://www.auduboninstitute.org
The Memphis Zoo: http://www.memphiszoo.org