The symphony of a Vermont spring is sung in a thousand small voices.

Robins whistle a soprano melody. Red-winged blackbirds punctuate the tune with their discordant squawk. Phoebes sing a long, plaintive aria, a flycatcher’s love song in the chill of an April morning.

To my ear, however, there’s no music quite like the wood frog’s defiant chorus, sung with the ice is barely off the pond and the ground still covered with patches of snow. Wood frogs sound like dozens of quacking ducks – hardly what you’d describe as a beautiful sound. No, the beauty comes from their timing: Wood frogs signal spring just when it seems the ugly gray of late winter will never give way to green. They’re often the first Vermont frogs to break winter’s quiet, beating spring peepers by a few days, or even a week.

Their vocal prowess extends to silence. If wood frogs sense danger of see movement on the fringe of their vernal pool, they cut off their song altogether, as though timed by some unseen conductor. The purpose of all this calling is finding a mate. Male wood frogs, once they’ve called in an unwitting female, can be tenacious in the extreme – even if their suitor happens to be the wrong species.

One frog researcher described finding a male wood frog hugging a female bullfrog so tightly that the bullfrog could barely breathe. Another researcher described accidentally putting a male wood frog in a jar with a spotted salamander. The salamander couldn’t dislodge its unwanted suitor, no matter how hard it tried.

There’s reason for this iron-lock grasp: in preparation for mating, the males’ thumbs will swell and the webbing of their hind feet will expand from being concave to convex. The thickened thumbs help the males maintain amplexus, or their mating embrace. Male wood frogs are smaller than females and the males ride on the females’ back during mating. The female lays eggs, and the males release sperm. In wood frogs, the fertilized eggs form a huge gooey ball of sometimes more than 3,000 eggs, often clustered around a twig or grass stem in the water. The tiny black embryo of each is surrounded by a perfectly round, clear envelope that’s about one-third of an inch in diameter.

Other frog species lay their eggs in characteristic ways, too. Spring peepers lay their eggs one at a time, attached to blades of grass or underwater weeds. Green frogs lay their eggs in a large film in the water. Leopard frogs lay eggs no more than a quarter-inch in diameter, with small dark embryos that fill most of the protective jelly around each egg, making the egg mass appear velvety black from a distance.

While wood frogs may swim around for an hour or more in amplexus, the actual time it takes for the female to lay eggs usually doesn’t take more than half an hour. Once they’ve finished mating, the frogs disappear in the woods, leaving their eggs to mature, or be eaten by predators, or to dry up, if the spring pool they’ve chosen is too shallow or it’s a particularly dry spring.

My favorite wood frog watching spot is a ditch by the side of the dirt road where I run. I like to take the kids to this ditch every week or so, to watch as the eggs become tadpoles, a process that can take as little as a few days, or as long as three weeks, depending on the water temperature. It can take another nine or ten weeks for the tadpoles to become little froglets, which explains in part why wood frogs mate as early as they do.

The toughest transformation to witness is that from froglet to true frog. Sometimes my ditch dries up before the frogs manage to make it out. Sometimes I’ll run by and see the ditch full of water, but magically devoid of froglets.

It’s easy to miss young-of-the-year wood frogs, because they’re usually no larger than three-quarters of an inch, and a fawn-colored brown designed to blend in perfectly with dried leaves, their preferred summer habitat. But it’s fun to find them if you can. They’re perfect miniatures.

Mary C. Dickerson, author of the Frog Book, a reliable and still mostly accurate natural history book written in 1906, sees in the wood frog a grace that most would reserve for larger creatures.

"The wood frog is beautiful at all times. It has a high-bred and delicate air," she wrote. "It is to the ground what the chickadee is to the trees – a gentle spirit of the woods. Its appearance and ways are always in harmony with the subdued light, the quiet, and the delicate mosses and frail ferns that live in the shade of great trees."