wood frog, the only amphibian in northern Alaska.
(photo by Mark Spangler)
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
The mating calls of several frogs ring off the eardrum. Its
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 UAF masters 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
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 dont 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 have
its kinks, but Spangler is excited to try it. Hell also use
a dipnet to gather frog eggs and larvae to help verify his eDNA
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 UAFs 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 Alaskas 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 on May 1 at the Creamers
Field Visitors Center from 4 to 6 p.m. He will follow that
with a field trip in the refuge from 7 to 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.