Mark Spangler, a UAF graduate student, is shown at a pond where wood frogs are singing on the UAF campus.

Mark Spangler, a UAF graduate student, is shown at a pond where wood frogs are singing on the UAF campus.

Alaska Science Forum: Calling frogs signal change of the season

NEAR BALLAINE LAKE — Over the blat of engines and hum of tires on nearby Farmers Loop, Mark Spangler hears the chuckles of the animal he is studying. Male wood frogs in a one-acre pond on the campus of the University of Alaska Fairbanks are singing a song of spring.

The mating calls of several frogs ring off the eardrum. It’s a piercing noise created by air in the inflated cheeks of a creature that could hide in a moose track.

“It only takes one bold individual to call and then they all jump in,” Spangler said.

The University of Alaska-Fairbanks master’s degree student wants to use a new technique to answer a basic question about the only amphibians in northern Alaska: How far north do they live?

“There are verified sightings in Anaktuvuk (Pass), Coldfoot and Wiseman,” he said of the farthest-north reported frogs.

Differing range maps show the wood frog living from Alaska all the way south to Georgia. The far-north version lives an astounding life. The frogs Spangler heard in late April were hard as rocks just weeks earlier.

Wood frogs freeze solid — even their hearts — as they hibernate each winter in a shallow cup of leaves and soil. Each spring, those adults thaw. They emerge to find their way back to a place like this — a pond that dries up and vanishes by summer solstice.

Perhaps wood frogs choose these ephemeral ponds to breed, lay eggs and generate tadpoles because they contain no fish that would eat frogs, Spangler said. Ideally, the water body lasts long enough for the entire life process from mating to development of tadpoles into adult frogs. When the frogs mature, they don’t seem to need water as much. People see them far from lakes and ponds.

To find out more, Spangler is dipping samples from wetlands on a road trip to the Arctic Ocean. Soon, he will drive north from Fairbanks and spend a week gathering water samples from here to the Yukon River. He will then continue north, sampling off the Dalton Highway north to Coldfoot. The week after that he will crest the Brooks Range at Atigun Pass and travel as far as Toolik Field Station. During his final week, he will drive all the way to Prudhoe Bay.

He is using environmental DNA analysis to determine if frogs were recently in the water he samples and filters. If a frog was in a certain body of water, its genetic material will, in theory, show up in his lab results. The technique is young and will has its kinks, but Spangler is excited to try it. He’ll also use a dipnet to gather frog eggs and larvae to help verify his eDNA results.

Why study frogs? Amphibians are among the most at-risk species in the world, Spangler said. And despite the work done on northern frogs by UAF’s Brian Barnes (who once glued radio transmitters to frogs and found out where they hibernated), we know very little about Alaska wood frogs.

“It could be they were always on the North Slope but nobody really noticed it,” he said.

As one of Alaska’s few herpetologists, Spangler is recruiting people for the FrogWatch USA program. He wants to enlist volunteers to monitor their favorite frog pond and report activity there to better understand frog populations in Alaska. In Fairbanks, he will run a training session for volunteers May 1 at the Creamer’s Field Visitor’s Center from 4-6 p.m. He will follow that with a field trip in the refuge from 7-8 p.m. He may host similar get-togethers in Anchorage and Juneau.

• Since the late 1970s, the University of Alaska Fairbanks’ Geophysical Institute has provided this column free in cooperation with the UAF research community. Ned Rozell is a science writer for the Geophysical Institute.

Pictured is a wood frog, the only amphibian in northern Alaska.

Pictured is a wood frog, the only amphibian in northern Alaska.

More in Neighbors

A reflection of a cold-water dip in Sitka Sound. (Photo by Bethany Goodrich)
Woven Peoples and Place: We are coming out of the water

For the second year, the Sustainable Southeast Partnership is releasing “Woven” as… Continue reading

(Photo by Gina Del Rosario)
Living and Growing: The call to pray the rosary

In many of the Marian Apparitions all over the world, the Blessed… Continue reading

Rich chocolate cream pie. (Photo by Patty Schied)
Cooking For Pleasure: Rich chocolate cream pie

About once a year I indulge myself with chocolate cream pie, using… Continue reading

Brent Merten is the pastor of Christ Lutheran Church, Juneau. (Courtesy photo)
Living and Growing: It wasn’t ropes or nails

Christianity Today published an online article during Holy Week titled, “Was Jesus… Continue reading

Jennifer Moses is a student rabbi at Congregation Sukkat Shalom. (Photo provided by Jennifer Moses)
Living and Growing: How we live our lives and pass on our values to our children

When my mother was dying of the breast cancer that had spread… Continue reading

Decluttering starts with making room on a desk for a list. (Winnie Au/The New York Times)
Gimme A Smile: Declutter like a boss

I’m trying to declutter. I pronounce those words in the same abashed… Continue reading

(Michael Penn / Juneau Empire file photo)
Living and Growing: It is all about the resurrection

This past weekend Christians celebrated the resurrection of Jesus. His resurrection from… Continue reading

Tortilla “dry soup” ready to consume. (Photo by Patty Schied)
Cooking For Pleasure: Tortilla ‘dry soup’ (sopa seca de tortillas)

This recipe is based upon one in an old Mexican cookbook I’ve… Continue reading

A rainbow spans the University of Alaska Southeast campus in September of 2024. (University of Alaska Southeast photo)
Sustainable Alaska: Reading relations

For the program’s 14th iteration, UAS’s One Campus, One Book committee selected… Continue reading

(Photo provided by Gina Del Rosario)
Living and Growing: Holy Week

Filipinos are known all over the world for their strong faith in… Continue reading

The downtown Juneau cruise ship dock on a clear March day. (Mark Sabbatini / Juneau Empire file photo)
Living and Growing: Seeking joy during times of great uncertainty

“This is the greatest act of power I have come to know:… Continue reading

Mary’s extreme bars, ready to slice. (Photo by Patty Schied)
Cooking For Pleasure: Mary’s extreme bars

For at least 20 years, my sister Mary Watson has been making… Continue reading