The great amphibian migration is underway in N.H. And it’s early.
Brett Amy Thelen has been helping amphibians cross the street for 18 years. She knows to keep an eye out for nights that are wet and warmer than 45 degrees, conditions when amphibians are likely to be on the move.
This year the migration is happening earlier than usual in southwestern New Hampshire, which experts attribute to the lack of snow. In the 18 years the Harris Center for Conservation Education has tracked amphibians, this is the second-earliest migration, which got underway on Feb. 28. The earliest recorded migration happened on Feb. 25 in 2017, according to the Harris Center.
Thelen, the center’s science director, said that’s because “this was the winter that wasn’t.”
Amphibians that participate in the migration spend the winter underground, and some of them have even adapted to freeze solid.
“That’s their strategy for surviving winter,” she said. “Wood frogs, spring peepers, they produce a natural antifreeze that protects their internal organs. Their lungs stop breathing, and they’re just kind of in suspended animation.”
Spotted salamanders, which can live up to 20 years, can’t survive freezing, so instead they go a few feet underground and spend the winter in warmer soil that doesn’t freeze.
When the ground thaws, it signals to amphibians it’s time to migrate from the wooded uplands where they spend the winter to the vernal pools and wetlands where they court and lay their eggs.
While their journey is usually short – typically no longer than a quarter of a mile – it can be deadly for the tiny critters that have to cross a road to reach their destination.
“It doesn’t take a lot of cars to do a lot of damage,” Thelen said.
“If they’re really getting slammed year after year, eventually you’re not going to have a population there,” she said.
The amphibians typically follow the same path every year, in many cases returning to the wetland where they themselves hatched. That’s how Thelen knows where to plan crossing brigades or to close roads. In the future, she hopes that by collecting data, New Hampshire can put in tunnels to help amphibians more safely cross under the road, an initiative that’s been successfully implemented in Vermont.
According to the Harris Center, their crossing brigades have helped more than 75,000 amphibians since 2007.
Keep an eye on the Harris Center’s website for the “Salamander Forecast” about when amphibians are expected to migrate this spring. The center is hosting a free training over Zoom for volunteers who want to help on March 14, and they have a list of other regional efforts to assist amphibians.
But the best thing you can do for amphibians? According to Thelen: Don’t drive on warm, rainy spring nights. Stay home.