gray treefrog

LC - Least Concern

N5 - Secure

S5 - Secure

not listed

Dryophytes is a genus of small treefrogs. Only two species occur in Minnesota, gray treefrog and Cope’s gray treefrog. The two species are almost identical in appearance, and are difficult to tell apart in the field, even by experts. The most reliable ways to distinguish between them is by listening to their calls or by examining their chromosomes under a microscope. However, the chromosomes are normally invisible under a light microscope. They become visible only when the cell duplicates.

Gray treefrog is a small, solitary, nocturnal frog. It is 1¼″ to 2⅜″ long at maturity. Females are larger than males.

The upper (dorsal) surface is warty. There are usually dark blotches outlined in black. The background color can change in seconds from green, light grayish-green, gray, brown, or dark brown. The color is determined by the color of the background, the season, and the humidity. It is most often some shade of gray. There is usually a large, irregular, dark blotch on the back. Beneath each eye there is a small spot. The spot is white or another light color, and it may be prominent or obscure.

The belly is white. On females the chin is pale olive-gray. On males the chin is darker gray.

The toes end in large adhesive pads. On males, the lower (ventral) side of the hind legs is bright yellow or yellowish-orange.

A slow trill lasting 1 to 3 seconds, not varying in pitch

1¼″ to 2⅜″

Cope’s gray treefrog (Dryophytes chrysoscelis) is almost indistinguishable morphologically. The dorsal surface is not as rough and is more often unblotched. If blotched, the blotches are often not outlined in black. The call of Cope's gray treefrog is a faster trill with about twice as many notes. They prefer more open habitats, including prairies and savannas.

Forest edges, wooded areas near permanent or temporary waters. Near street lamps and lighted buildings at night.

Adults are usually found high in trees, on mossy or lichen-covered fences, or sometimes in abandoned bird houses. They are rarely found on the ground except in breeding season.

During breeding season the adult’s background color is usually green.

Unknown. Probably 5 to 7 years.

Breeding occurs from April to July, peaking in May to June. After breeding, the female will deposit 450 to 600 packets of 30 to 40 eggs each on emergent vegetation at the surface of a shallow pond or a permanent or temporary pool. The eggs hatch in about three weeks and metamorphosis occurs about four weeks later. The tadpole is about 2″ long preceding metamorphosis.

Adults live 5 to 7 years. They overwinter under the shelter of a log, rock, bark, or leaf litter. They are freeze tolerant and can survive multiple freeze-thaw cycles. Glycerine is produced preventing the formation of ice crystals in vital organs.

Algae, material from dead and decaying plants and animals (detritus).

Insects, insect larvae, mites, spiders, plant lice, harvestmen, snails, and smaller frogs.

Sources

4, 14, 24, 29, 30, 73, 76, 78.

Common

Gray treefrog and Cope’s gray treefrog were, until 1968, considered the same species.

The genus Dryophytes was originally described in 1843. In 1882 all Dryophytes species were transferred to the genus Hyla, which then contained all treefrog species in the Northern Hemisphere. In 2014 North American species were placed in the new subgenus Dryophytes. In 2016 the subgenus was raised to genus level, resurrecting the original genus. Today, the genus Hyla now contains only Old World species. All North American treefrog species, and three species in temperate eastern Asia, now belong to the genus Dryophytes. The last move was not universally accepted.

Location: Albany, NY

Location: Winona County

Location: Beltrami County