Wisconsin Sea Grant Frogs: Field Guide

Copes Gray Treefrog
(Hyla chrysoscelis)

Call: A fast, harsh, buzzing trill usually lasting less than a second

Size: 3-6 cm in length (1.2-2.4 inches)

This frog has considerable color-changing ability; the same frog can vary in color from light gray to brown to pale green; one or more dark irregular blotches, sometimes outlined in black, may be visible on the back; a dark stripe or band often slants from the back of the eye to the front leg; belly is white, and there is a patch of bright yellow or orange under the hind legs

Favoring grasslands and savannas, these frogs also utilize farm woodlots, swamps, old fields, and suburban yards -- almost anywhere where breeding ponds are near trees or shrubs; most common throughout the western and southern portions of the Great Lakes region.

Confusing Species:
This frog is virtually identical to the Eastern Gray Treefrog, though the Eastern Gray Treefrog tends to be slightly larger and bumpier-skinned. The calls differ, however, and Eastern Gray Treefrogs have twice as many chromosomes as Cope's Gray Treefrogs.

Breeding: Early May to late June

FACT: Both the Cope's Gray Treefrog and the Eastern Gray Treefrog are most active at night, when they look for food in low shrubbery or in trees. They are talented climbers, and may scale trees to heights of 30 feet or more above the ground! A special mucus produced on their toes gives them an extra-sticky cling and helps them climb even smooth surfaces.

Did you know?

Gray Treefrogs cope with cold temperatures in an unusual way -- they literally freeze!

Experiments have shown that Gray Treefrogs can survive temperatures as low as -6 C (21 F) for several days, when more than 40% of their body fluids may be completely frozen.

They accomplish this by producing large amounts of glycerol in their blood and body tissues, which acts as a natural "antifreeze" to prevent ice from forming inside their cells.

copyright 2001 University of Wisconsin Sea Grant Institute


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