A lumbering yellow road grader fills potholes and washboard ruts along our dirt road; a welcome sign of spring. Mud season’s nearly over and it’s almost dry enough to consider washing the car. Living at the edge of a forested swamp and open marsh along a rural dirt road, we witness an annual parade of marching salamanders and frogs hopping across the road in April. There’s little, if any, other traffic after 8 pm.
And that’s a good thing.
Because on rainy nights, the writhing columns of yellow-spotted black salamanders, black-masked wood frogs and tiny spring peepers cross many roads statewide. This mass migration statewide links amphibians living for most of the year in forests to temporary, fishless “vernal pools” the temporary pools of spring melt-water.
Most amphibians return to their natal pools – the very places they first hatched - to mate, lay eggs and return to the woods, leaving eggs and larvae behind. Spotted salamanders may live up to 20 years and can migrate 200 meters. Wood frogs may travel more than a quarter mile to breed. During April droughts or years with late ice or snow cover, they may skip breeding entirely and try again next year.
The annual amphibian migration is a celebrated rite of spring for many naturalists. The timing of what vernal pool aficionados affectionately call the “big night” varies across the state depending on local conditions. Steady overnight rain and temperatures above 42 degrees are ideal for wood frogs and spotted salamanders to migrate en masse. The White Mountains region and areas at higher altitudes typically lag a few weeks behind the Lakes Region and southern NH. Keene and the Seacoast communities typically report the earliest migration activity in March.
Their journey across busy roads grows more perilous in developed regions of New England. Amphibian road mortality statistics are shocking. A study in western and central Massachusetts determined road kill rates even relatively quiet roads can be high enough to lead to localized extirpation of spotted salamander populations in a few decades. Another study found that 50-100% of salamanders attempting to cross a paved road in rural upstate New York don’t make it.
In response, the Ashuelot Valley Environmental Observatory (AVEO) trains volunteers to assist amphibians crossing busy roads along established migration routes near wetlands. According to Brett Amy Thelen at The Harris Center for Conservation Education, there are typically 100 to 125 active volunteers manning salamander “Crossing Brigades” during peak migration nights.
Last month on March 31 at North Lincoln Street in Keene, volunteers moved 352 wood frogs, 452 spring peepers, and three spotted salamanders across a stretch of road less than a tenth of a mile long in just under four hours. In the past six years, Crossing Brigade volunteers have saved nearly 13,000 amphibians from tires in the Monadnock Region alone. In the Manchester area, Massabesic Audubon Center, volunteer Rick Glatz offers training and maintains an active call list to notify Brigade volunteers during April “Big Nights.”
The amphibian migration is ancient. High speed traffic along asphalt roads is a relatively new landscape feature. Anyone can help by avoiding driving entirely on rainy nights in April. Awareness helps – when driving on rainy nights, slow way down near prominent wetlands to safely avoid hitting individual frogs and salamanders. The AVEO website has tips and maps for those interested in learning more about how they can help: http://www.aveo.org/citizen-science/salamander-crossing-brigades/other-amphibian-crossing-programs/
On a Big Night, volunteers may see hundreds of wood frogs and dozens of salamanders at a single site in the span of a few hours. Sometimes volunteers with flashlights, wearing raingear and reflective vests and holding clipboards in the dark elicit concerns from local residents or law enforcement officials.
Brett Thelen tells a story of driving home after 11 pm from a crossing brigade at 10 mph with hazard lights blinking and pulling over every time she spotted a salamander or wood frog. A police officer stopped her to investigate. “When I explained I that I was moving salamanders and frogs across the road so they wouldn’t be hit by cars, he nodded and said, ‘Oh yeah. My wife used to do that with her friends over in Chesterfield,’ and sent me on my way. Not the reception I was expecting to get!”
Crossing Brigade volunteer, Mary Wright from Gilsum explains the reason why she remains dedicated to the Herculean task of assisting salamanders and frogs to cross busy roads: “It’s important for the Earth; it feels really good to be doing something positive; and it’s a hoot to know there are other slimy-fingered loonies out there in the middle of the night sharing the thrills and the heartaches.”