CA Press: Zoo makes a leap in fight to save frogs

[Herp News]

UNION-TRIBUNE (San Diego, California) 25 July 09 Zoo makes a leap in fight to save frogs - Conservation institute raises egg to adulthood (Scott LaFee)
As jumping amphibians go, the mountain yellow-legged frog is a lump on a log compared to its famous red-legged cousin, the celebrated subject of Mark Twain's 1867 tale. But two recent encounters with yellow-legged frogs near San Jacinto Mountain, northeast of San Diego, suggests its own short story.
The frog sightings, made by independent teams from the U.S. Geological Survey and the San Diego Natural History Museum, are the first in almost a half-century in the region.
Once abundant in California, the mountain yellow-legged frog (Rana muscosa) crouches on the verge of extinction. The total known number of adult frogs remaining in the wild is estimated to be 122 – all living in a handful of small, isolated pockets of the Sierra Nevada, San Gabriel, San Bernardino and San Jacinto mountains.
On the upside: The San Diego Zoo's Institute for Conservation Research has just announced it successfully nurtured a yellow-legged frog egg to young adulthood. That's never been done before in captivity.
Zoo conservationists hope to eventually produce scores of eggs and tadpoles for reintroduction into the wild. “Perhaps as early as 2010,” said Jeff Lemm, a research coordinator. In the meantime, the two wild frog sightings suggest there may be more suitable places to put them. And more frogs to welcome them back.
“Discovering the (wild) frogs could be huge,” said Adam Backlin, a USGS scientist. “Not because it's two more frogs, but because the frogs were found in habitat that's much larger than any of the other known populations. That means there might be a lot more frogs in the area. We might be looking at more animals here than all of the other known populations together.”
Backlin discovered the first frog – a single adult – while hiking along Tahquitz Creek in the San Bernardino Forest's San Jacinto Wilderness in early June while scouting potential reintroduction sites.
He passed the news to the museum team, which is retracing a 1908 museum expedition to the region. Museum researchers are comparing modern vertebrate numbers and species in the area with observations taken more than a century ago.
Drew Stokes, a museum biologist, found the second frog sunning itself on a tributary of Tahquitz Creek. “It helped knowing where to look – and how to look – because these frogs are hard to find. If they see you first, they're gone before you see them.”
Backlin and Stokes say it's reasonable to assume the frogs are distinct individuals because the species tends to stick close to a water source. The frog sightings were roughly 2½ miles apart.
That relatively lengthy distance encourages biologists because it suggests the creek habitat where the frogs were sighted might house a lot more of them.
“Assuming that entire stretch is occupied, it's a larger piece of (yellow-legged) frog habitat than anywhere else known,” said Stokes.
Like amphibians around the world, mountain yellow-legged frogs (and a northern version known as the Sierra Nevada yellow-legged frog) are in steep decline. The species is classified as critically endangered on the World Conservation Union's Red List.
There appear to be multiple reasons for the frog's disappearance. Chief among them are predatory fish. A century ago, yellow-legged frogs lived in fish-free lakes and streams at high elevations. Trout and other non-native fish were subsequently introduced to boost recreational fishing. Trout are voracious consumers of tadpoles.
But predatory fish are just the most obvious threat. Perhaps more devastating is a fungus called Batrachochytrium dendrobatidis, which has spread around the world, often wiping out entire amphibian populations. It is believed to be a major driver in the global decline of frogs.
Yellow-legged frogs have been impacted by other factors too: habitat destruction, pesticide poisoning, pollution, drought and ultraviolet radiation.
The USGS, U.S. Forestry Service and U.S. Wildlife Service are coordinating efforts to restore the frogs to some of their original range. The challenge has been to find suitable habitat and, naturally, frogs to fill it.
In 2006, a USGS team led by biologist Robert Fisher rescued 82 tadpoles from a pond drying up in Dark Canyon in the San Bernardino National Forest. The tadpoles were taken to the San Diego Zoo, where Lemm and colleagues managed to raise 62 of them to adulthood.
“That's a huge number because amphibians are always tricky in captivity. You never know what might happen with them,” said Lemm. “These frogs live at high elevation in crystal clear cold water. Trying to emulate that environment has been a challenge.”
When some of the surviving frogs produced eggs late last year, researchers were stunned and ecstatic, especially since no one yet understands the optimum conditions necessary for yellow-legged frog reproduction. Indeed, herpetologists are not sure where the frogs go during winter hibernation.
Most of the eggs proved to be infertile, a common phenomenon among juvenile frogs. But one egg did hatch and has matured into a froglet. It won't reach sexual maturity, however, for perhaps two more years.
Lemm said zoo workers are busily experimenting with environmental cues to hopefully prompt more egg-laying and tadpole hatchings next spring. In time, he believes the zoo – and other zoos that will receive some of the original 62 frogs – will be able to produce as many eggs and tadpoles as needed for reintroduction programs.
These frogs, it's safe to say, won't be named like the very first one.
“He's called Han, as in the Star Wars character, Han Solo.”
Zoo makes a leap in fight to save frogs

[quarterback26]

wow!
And I like his name