Wild Profile: Meet the gray treefrog

A gray treefrog on a branch By Natalia Kuzmina/Shutterstock

The gray treefrog truly earns its name: this frog loves trees. And it’s why cottagers may never notice the amphibian—who looks for frogs high up in the canopy? But the gray treefrog is also a master of disguise. The species has transparent skin over three layers of pigment cells. By expanding and contracting the cells, the frog can change colour from bright green to various shades of grey, depending on the surroundings. On cool days, they’ll turn nearly black—this allows them to absorb as much of the sun’s heat as possible. The colour change takes about half an hour.

The gray treefrog is nocturnal. But an eagle-eyed cottager might spot young froglets—they’re about the size of a cricket—hunting for insects near ponds and lakeshores. Young treefrogs have smooth skin. As they get older, their skin becomes rougher and bumpy, more like a toad’s.

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On rainy evenings, treefrogs prefer to hunt in trees. Thanks to their chameleon-like abilities, they can blend in perfectly with bark and lichen. They’ll stay motionless for hours, until they spot a bug mid-air. Then—ka-boing!—the frog can leap a metre high, snatch the insect, and land on another tree branch. Gray treefrogs will also sometimes scale cottage walls or windows at night (they have sticky toe disks that allow them to cling to even smooth surfaces).

By early fall, a gray treefrog descends from the trees for the season and snuggles under leaf litter or rocks to wait out the winter. With plentiful snow, the frog stays well-insulated through the cold months. If not, thanks to high levels of glycerol and glucose in their bodies, about 65 per cent of a treefrog’s body fluids can freeze without damaging any internal organs. Treefrogs tend to hibernate longer than other amphibians—many won’t wake up and take to the trees until mid-May.

Quiz: How much do you know about hibernation?

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