Olympic National Park, Wash. — Maureen Ryan scales rocky trails at 5,000 feet elevation as nimbly as the mountain goats that wandered through camp earlier this morning.
The amphibian researcher leads her team of scientists down off a ridge line in the Seven Lakes Basin of Olympic National Park to her “lab”, you might call it. It’s a series of pothole wetlands cupped in the folds of these green, snow-studded mountains - perfect habitat for Cascades frogs (Rana cascadae).
Ryan, a researcher with the University of Washington, is an expert on alpine amphibians. She’s also part of a group of scientists from around the region, coordinated by the Amphibian Research and Monitoring Initiative at the USGS, who are trying to understand and project how the warming climate will affect these frogs’ ability to feed, mate, and ultimately, survive.
Cascades Frogs Facing Climate Change
“This is one of the things we’re really concerned about,” she says, pausing on the banks of a warm sunny pond about the size of a backyard swimming pool. “These sorts of sites start drying early or drying at higher frequency and that can have really big effects on the biological community.”
You’ll only find the Cascades frog at high elevations in the Northwestern part of the U.S. (although their range used to extend down to the Northern Sierras and into British Columbia) where they’ve adapted to spending nine months of the year beneath dozens of feet of snow.
For a few short months in the summer they come to warm sunny ponds — like this one — to feed and mate. And while they’re at it, they make what some describe as a chuckling sound. But we’ll get to that later.
Ryan’s brow furrows with concern as she scans the pond.
“It’s actually dried out quite a bit this year,” she says.
And last year, she adds, was worse.
“We had a good number of ponds where the ponds dried up before the tadpoles had metamorphosed so they didn’t survive there, and that gives us some idea of what things might look like in the future even though it was an extreme year,” she says.
But now comes the fun part of this research.
The team fans out, squelching through the muck, on the lookout for the signature dappled brown and yellow heads of the frogs. Most of them are about the size of a child’s hand. Their bug eyes peer out at us from beneath the shelter of the banks.
After the team has circled the pond and caught about 30 frogs, Ryan pulls out a device that looks like the scanner at the grocery store check out. It’s called a pit tag reader and as Ryan holds it over the back of one of the frogs it lets out a “beep” telling us the frog has a rice-grain-sized chip implanted under its skin with an ID number. “Then we’ll know the history of that frog,” Ryan explains. It doesn’t harm the frogs.
The team has been inserting PIT tags in this population of frogs for more than a decade.
“We have some frogs that we’ve caught that we know are 13-14 years old and might be older,” she says, pausing with a small male frog cupped in the palm of her hand. “It’s pretty amazing.”
And more importantly, it allows the scientists to chart the growth of the frogs over the years and to map the ways in which they’re using the existing habitat.
A map of Cascades frog movements in the Seven Lakes Basin of Olympic National Park. (Courtesy of Maureen Ryan)
Along with their frog scanning, the team is monitoring the temperature and depth of ponds like this one. They want to find out when they’re drying up during the course of the summer and how that might affect frog movement.
Ryan worries that with less snowpack and hotter summers more egg sacks and tadpoles will be stranded out of water. That could ultimately decimate the population, unless they can move into deeper alpine lakes that are more resilient to the warming climate.
The problem there is that many of those lakes have been stocked with trout for recreational fishing – and the trout find the Cascades frog delicious. Some fish removal operations in the Cascades have proven successful in creating new safe habitat for these frogs. Ryan would like to see more of that happen in the future as a mitigation measure to help the frogs adapt to climate change.
We move on to sample several more ponds. We’re seeing lots of frogs, but still haven’t heard the alleged “chuckling” call.
Maureen Ryan says we’re going to check out one more site. She bounds off through the snow and motions me to hunker down with her in the heather along a snow-lined pond. The frogs are all around us, but they’re silent, just staring at us – like we’re unwelcome party crashers.
Ryan gestures around us slowly, like a commanding officer on a stealth mission. “One on the rock, one in the grass,” she whispers. “Two that are right under us and another one under the bank over there.”
Then, we hide ourselves from frog-view, hunkered down in the heather, listening.
And then it starts. Slowly at first. A chuckle here, then another a few feet away. Then the sounds grow louder. More frogs join in. Soon it’s a veritable comedy hour laugh-track of mating Cascades frogs.
“They’re just funny. Everything about them is funny,” Ryan says. Her eyes sparkle. “Their legs are funny, their voice is funny. It’s funny that they hang out under the snow for nine months.”
Human and frog chuckling fades away and Ryan pauses, her brow furrowing again slightly.
“The Pacific Northwest has lost about 50% of its snowpack over the last 50 years. If that trend continues it’s going to have major implications for us, as well as the frogs.”
“I’d love to be wrong on all of it,” she goes on, reflecting on her research and the projections of future hardship for these amphibians. “Do I think we’re wrong? No. Do I wish we were? Yes.”