(almost) Invisible amphibians

Naturalists search for Juneau's hard-to-find toads, frogs and newts

Posted: Sunday, October 13, 2002

Richard Carstensen has a job his sixth-grade nephew would envy. He gets to wander through the muck looking for frogs, toads and newts.

Carstensen, Bob Armstrong and Mary Willson are part of a Discovery Southeast team under contract to study Juneau amphibians and their habitat for the state Department of Fish and Game. Discovery Southeast is a Juneau-based nonprofit nature education group that works in local schools.

The group did some preliminary work on the project last summer and spring and will continue through next fall.

Hunting for toads is more than just child's play. Scientists in Southeast are concerned about anecdotal reports of a drop in the population of toads here in the 1990s.

"Nobody has proved that they are declining in Southeast," Carstensen said. "Amphibian (populations) are notoriously boom and bust and sensitive to environmental change, so maybe we're just going through a down period right now."

Declines in western toad populations in a number of Western states, however, are well documented, Carstensen said.

The local population has not been studied well enough to say if that's happening in Juneau, but people who have lived here many years say toads were once so common people had to be careful not to step on them while hiking at dusk. Now sightings are rare.

Scientists point to several possible culprits for the decline in other states, including pollution, introduction of predators or competitors, drought, dams, road construction, recreation near breeding sites, parasites, increased ultraviolet radiation due to a thinning ozone layer and changes in weather, possibly due to global warming.

Some of those factors could be at play in Juneau, Armstrong said. He wonders whether milder winters with less snowfall have left hibernating toads without enough snow cover to insulate them during cold snaps.

"We actually know very little about their winter habitat," Armstrong said.

Another possibility is that warmer winters may have given a leg up to a naturally occurring fungus that can harm toads, Armstrong said. A combination of several factors could be behind the possible decline, he said.

Why should we even care about these not-exactly-cuddly critters?

"They're an early indicator of change, changes that might eventually affect humans, or things humans depend on," Armstrong said.

"In some areas they're really important ecologically," Carstensen added. "They could be the most important predator on insects" in those areas.

The Discovery Southeast team is not going to answer the question of why or even whether the toad populations in Juneau are in decline with its study. The team is simply charged with documenting current populations and describing known or likely amphibian habitat in Juneau.

Carstensen said Juneau's amphibians have been studied so little researchers don't even know where to look for them in a systematic way. Having a better understanding of their habitat could help direct studies in other parts of the Tongass. It could also help land managers decide what areas may need protection.

The study should provide a foundation for further research. Because the work will be along the Juneau road system, it will be relatively inexpensive for researchers in the future to return to the same sites and gather new information.

The researchers have found three types of amphibians living in Juneau - the once-common western toad; the wood frog, which they had not seen before in Juneau; and the rough-skinned newt, which was introduced from Shelter Island in the 1960s.

Based on other researchers' work and the team's observations last summer, Carstensen said the best breeding ponds for toads and other amphibians are warm and shallow and have little water flowing in or out during the summer. They also generally were created relatively recently - for instance, by receding glaciers, beavers or human disturbance.

Amphibians often breed while ice is still on ponds, so early spring will be a prime research time for the team. If they find amphibians, they'll count them, take measurements, check the sex of adult specimens and note any abnormalities.

The researchers also are asking Juneau residents to let them know of sightings - now or in the past.

A Fish and Game employee, Karla Hart, is talking about throwing a "toad party," and inviting people who grew up in Juneau to point out past sightings as precisely as they can on a map, as well as dates they were seen.

Although the team would like help from the public, people should avoid handling the critters themselves, Carstensen said.

Many adults have fond memories of collecting tadpoles and bringing them into the house to watch them turn into toads, but this really isn't a good idea, Carstensen said.

For one thing, it's illegal without a Fish and Game permit. And doing so could hurt a population that already appears to be in trouble, he said. Also, captive amphibians can't be returned to the wild without a risk of introducing diseases into the natural population.

Even picking up a toad out in the woods can hurt it because they have very absorbent skin and can be poisoned by sunscreen, insect repellent or nicotine on a person's hands, Carstensen said.

He suggested people who want their children to learn more about amphibians contact Discovery Southeast, 463-1500, about the possibility of getting an educational permit to raise them in a school classroom.

For more information on the project, people can contact Carstensen at richard@discoverysoutheast.org.

Cathy Brown is a Juneau writer who has worked for the Empire and The Associated Press.



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