Where to Find the Frogs in Lexington

It's hard to photograph a frog nowadays. That isn't to say that the frogs aren't around. They are. My son tried to catch one in Whipple Hill just this week, but ended up with only a net full of leaves and mud. The frog was too small, too brown, too fast for a winter-weak boy to catch as it leapt into the March cold water.

The frog was highly motivated to escape. It was a wood frog, and on its way to mate and catch up on the stats for basketball games it might have missed while snuggled down for the winter in the rotting stump or shallow burrow.

In all honesty, “snuggled” is hardly the right word for what these frogs do. According to the U.S. Environmental Protection Agency, “Unlike frog species that hibernate under water, wood frogs are freeze-tolerant and pass the winter with their circulation and respiration stopped and much of their body tissue crystallized into ice.”

The reason that the frogs are in such a frenzy, though, has to do with where they mate. While wood frogs are perfectly content to freeze solid in a unheated stump for the winter, they're fairly fussy about their tadpoles' lodgings.

Wood frogs lay their eggs in vernal pools. In plain English, vernal pools are very large puddles in the woods that dry up in the summer. Fish can't live in them, so cute little polliwogs have a much better chance of surviving than in waters where they would meet Larry the Lovable Largemouth Bass.

In Massachusetts, vernal pools are considered important natural resources, but not all puddles are vernal pools. The Massachusetts Natural Heritage and Endangered Species Program (NHESP) offers extensive instructions on how to detect if your local forest puddle is a vernal pool, or just a bit of sylvan swamp.

The difference is what lives there. If you can document evidence of certain species living and breeding in the pond, you can have your micro-pond certified as a vernal pool by the state – and woe betide anyone who attempts to build on that land!

The NHESP even prints a disclaimer on their forms that reads “THE NHESP STRONGLY RECOMMENDS THAT LANDOWNDER PERMISSION BE OBTAINED PRIOR TO COLLECTING CERTIFICATION DOCUMENTATION.” Despite these grave admonitions, Lexington has 12 certified vernal pools and ca. 70 uncertified pools, according to the 2009 Town of Lexington Open Space and Recreation Plan Update.

Fortunately, wood frogs don't care much for government paperwork. They hop on into their favorite pools in mid-March whether they're certified or not. Since vernal pools dry up by midsummer, wood frogs only have a limited time to mate if they want to make sure that Junior's gills don't get parched before he's developed lungs. And that time is now.

By next week, the blue spotted salamanders will be slipping into their own vernal pools for mysterious congresses, which seem to involve as much squirming into salamander balls as egg-laying and sperm-depositing. (There aren't any salamanders in the Whipple Hill vernal pool my family visits; when the houses were built on Winchester's High Street, the salamanders stopped coming.) The wood frogs wills start quacking then, making their ducky calls on warm afternoons. A week or two later, the spring peepers will dare you to find them, going silent and still if you step an inch too close.

 While you may admire your screaming yellow front-yard daffodils and royal purple pansies, they're awfully quiet. Go explore one of Lexington's 82 certified and alleged vernal pools. The little brown and gray frogs may not be much to look at, and impossible to photograph – but they make the sound of spring.