April 16, 2014 —
A week ago Thursday, the morning was chilly, but the forecast called for mild temperatures and sunny skies. I wanted to check out the Tusten trail and it promised to be a good day for a hike. Most of the way up the steep part of the trail, in a small pond near a seeping rock outcrop, I heard a harbinger of spring: an army of wood frogs.
Wood frogs (Rana sylvatica) are one of the first species of amphibians to emerge during spring, sometimes being heard before the more common spring peepers. The call of a wood frog is more like a quack than a croak (listen here at www.twcwc.com/sounds/woodfrog.wav ) and you will hear these calls for only a week or two as small vernal ponds and other pools of water start losing their ice cover. The pond that I saw was right next to a rock ledge and still half covered with ice, and some of the frogs were sitting on that ice. Most of the other frogs were in the water calling or mating, their heads visible as they moved about between the shore and the ice edge in the middle of the pond.
A female wood frog will lay from 1,000 to 3,000 eggs; females often lay their eggs communally. Egg masses over a foot in diameter are not uncommon. After about three months, small wood frogs emerge from the water and disperse to the forest; like grey tree frogs and American toads, wood frogs do not need nearby water in their non-breeding habitat. After two to three years, these young will return to the pond in the spring to breed for the first time themselves.
Other than breeding time, wood frogs spend most of their time in the forest. They can vary in color from dark brown or grey to tan; a few individuals will display green patterns. The most prominent feature is a dark “robber mask” that stretches from the snout, past the tympanum to the foreleg. At only three inches, they are not very noticeable, but you may spot them at any time during the warm months in their woodland habitat.