The song of the gray tree frog (Hyla versicolor) is a poignant reminder that our local woodlands have reached their spring peak. The threat of frost has passed, and the woods are fragrant now with showy wildflowers and soft, bright green leaves.
This tiny frog’s call is at least as much a part of these woodlands as any migrant songbird’s, and, best described as a melancholy trill, it is in many ways more indicative of the health of a local wetland than birdsong.
Dave Taft Though they are widespread in New York City’s five boroughs, gray tree frogs are rarely noticed by park visitors or wetland hikers. The frogs can change color, but generally range from a warm, muted gray to mossy green, rendering them hard to detect among the branches and tree bark they prefer.
At an inch and a half, gray tree frogs are rather toad-like in their pudgy proportions, making their considerable climbs though the trees that much more remarkable.
Even so, the frogs are generally homebodies, and never range far from the vernal pools of water where they were born.
Few animals seem as ill-suited to an arboreal life as a frog. Their need for damp conditions, their sometimes clumsy hopping (or more properly, their sometimes clumsy landings), and their need to lay eggs in water, all seem to be a poor fit for life in a tree. But frogs have surmounted the challenges.
Locally, the very early breeding spring peeper and the gray tree frog are abundant examples of this success.
The climbing ability of tree frogs is based largely upon their toe pads; circular discs exude a tacky mucous that allows the frog to stick to branches and leaves in the wild â€" or your windows and aluminum siding if you are lucky enough to live near a population.
These frogs are generally nocturnal and are sometimes drawn to the insects circling lit porch lights on warm spring and summer evenings. They are particularly active on humid or wet nights.
In fact, traditional folklore imbues them with the ability to predict rain. This is unlikely, though the frogs are certainly more active, and inclined to call when humidity rises prior to, during and after a warm summer rain.
Even admirers of these beautiful gnome-like creatures are frequently unaware of one of their most unusual adaptations. The gray tree frog can survive body temperatures well below freezing during the winter months.
While in this nearly frozen state, the frog’s heart stops beating completely, its lungs cease working, and its brain activity is almost unmeasurable. This adaptation is shared with a few other northern-ranging reptiles and amphibians that must survive months of potentially sub-freezing temperatures in order to survive.
This tree frog “trick†is accomplished by producing high concentrations of glycerol, a natural antifreeze, which prevents ice crystals from forming and rupturing delicate cell structures and compromising important internal organs.
And so in spring, the frog awakens, stretches like Rip Van Winkle, and hops off into another lush green world.
