CALLING ALL TOADS – Jaime Welfelt, a biologist with the National Park Service, searches for signals from boreal toads, which she has fitted with transmitter belts. Once she locates the toads, which can be difficult at times, she is able to see how they are living. Toads have been on the decline for several years in Dyea. Photo courtesy of Klondike Gold Rush NHP

Park tracks Dyea’s boreal toads with new radio study


There is a new radio program broadcasting live from Dyea, and it’s not part of KHNS.

This is the first year Klondike Gold Rush National Historical Park is using radio tracking to study boreal toads, said park biologist Jaime Welfelt.

Welfelt is in her second season of tracking the Dyea amphibians in hopes of better understanding their hibernating habits.

Unlike their Yukon relative the wood frog, boreal toads cannot freeze when temperatures drop.
“Wood frogs can freeze solid during the winter,” Welfelt said. “But the toads have to hibernate.”

Toads are ectotherms, which means they regulate their body temperatures by exchanging heat with their surroundings.

Past studies have shown the toads preferred to hibernate communally in hollow logs, she said. Boreal toads have also been known to chose spots that are insulated with a snow covering.

“Part of the tracking study is to locate these important features of hibernation and make sure we can preserve them,” she said.

Right now, there are four toads with plastic belts and radio units that weigh less than two grams.
Welfelt tracks them at least once a week to ensure their belts are fitting correctly.

Each belt transmits a different frequency, so when Welfelt tracks them, she sets the frequency on her antenna to the belt of the toad she is looking for. She then walks through areas of Dyea waving the antenna in a semi circle in front of her body, following the beep of the signals.

“It can take 10 minutes to find them if they are in a grassy, flat area,” Welfelt said of the toads, “But it could take up to three hours if they are in the middle of the alders and have traveled a long distance from where they were last tracked.”

Because the toads are small, growing up to about 5 inches at their largest, and are the same color as the ground, Welfelt said they can be difficult to spot.

“Sometimes I’m on all fours crawling around through the Devil’s Club trying to find them,” she said with a laugh.

When she finds the ones she’s looking for, she picks them up, makes sure everything is OK with their belts and puts them back down.

“They aren’t super happy about it,” she said of the handling. “But when I put them down, they go right back to whatever they were doing.”

Left, A toad is tested for chytrid, a lethal fungus which is responsible for toad population declines all over the world. Right, A group of boreal toad metamorphs are found near breeding ponds in Dyea. Park biologist Jaime Welfelt said out of about 10,000 toad eggs, usually only one makes it though all four life cycles stages to adulthood. Female boreal toads lay one long double strand of eggs in the ponds every other to every three years, and the egg strands are the only indication of female population numbers. This year, Welfelt found about 25 strands in Dyea, meaning there are at least 25 female boreal toads in Dyea this year. Courtesy of Klondike Gold Rush NHP

After each tracking, Welfelt maps the toads’ individual locations with Global Positioning System (GPS), so when the tracking period is over in September, the park will have a comprehensive map of where each toad travelled during the course of the study.

Welfelt said she hopes the boreal toads will be hibernating by the time the belts come off, so she can take a closer look at their winter habitats.

Because the toads’ actions are temperature dependent, a colder than average year could potentially kill off some of the area’s population, which Welfelt said used to be significantly higher than it is today.

“In Dyea, you couldn’t ride your car or walk without running over or stepping on hundreds of toads,” she said, adding that the population has since dwindled significantly.

Though they have not been able to nail down an exact cause, the park thinks there could be several contributors.

Because of their unique life cycle between water and land, amphibians are very sensitive to environmental changes and pollution,” Welfelt said, adding that the combination of building development and draining wetlands produce a disturbed environment to which the toads could have become too sensitive.

Also, chytrid fungus had made an appearance in Dyea over the years.

Chytridiomycosis is a lethal skin disease and responsible for the decline of amphibian populations worldwide.

According to an April New York Times article, “the disease appears to affect only amphibians, and some species are immune to its effects while others succumb rapidly. It causes the amphibians’ skin to thicken and leads to cardiac arrest.”

Welfelt said the fungus is not native to the area, so when she is moving from site to site, she sanitizes all of her equipment to keep it from spreading.

Discovering how the toads spend the 11 months they are away from the breeding ponds is crucial to helping conserve Dyea’s small remaining boreal toad population, she said.

It could also allow Welfelt to discover the toads’ migratory corridors and additional breeding ponds in the area.

“With the radio tracking, I can take a peek into their lives and see what they’re doing and where they go,” Welfelt said. “This study is allowing us to see how to better understand and protect them.”