Gray Treefrog (Hyla versicolor)

Description: Gray treefrogs are not always gray; in fact, they are frequently green, but also may be light brown. Their Latin specific name, versicolor, refers to their ability to change color in response to changing temperature, humidity, and light. The dorsum of this species often has a ragged, star-shaped pattern. The venter is white in both sexes, but males have a dark throat, while females and young adults have just a few flecks of black on the throat. Under each eye is usually a black-bordered, light square. The yellow-orange surface of the groin and hind legs is hidden when the frog is sitting, but is exposed when it leaps or is handled. Natural selection has "designed" this frog to be color-matched to its usual background, mostly lichen-covered tree trunks and branches.

This species can be distinguished from the spring peeper by size, skin texture, and the color pattern. The gray treefrog is twice as large as the peeper, with females sometimes reaching 6.7 cm (2.6") and males ranging from 3.2 to 6 cm (1.3-2.4") (Wright and Wright 1949); an Orono population averaged 6 cm (2.4") for females and 5.3 cm (2.9") for males (Hinshaw and Sullivan pers. comm.). Its skin is so warty that many people mistakenly refer to it as a treetoad. The peeper, on the other hand, has smooth skin.

The dark green or black tadpoles grow to 4.5-5 cm (1.8-2.0") and sport colorful wine, scarlet, or rose tailfins that extend along the back (Wright 1914). Newly emerged frogs are emerald green and average 1.6 cm (0.6").

Voice: The mating call of a gray treefrog is a short, melodic trill that averages less than half a second (Taigen and Wells 1985) with 3-7 seconds between calls (Fellers 1979a). Females prefer long-duration calls at a high broadcast rate (Sullivan and Hinshaw 1992). Other anurans with vocal trills are the American toad and the spring peeper. The toad's trill is distinguishable because it is much longer (6-30 seconds).The peeper's encounter call, given at the opening of a bout of calling or when a neighbor is too close, may last 720-940 msec (Rosen and Lemon 1974) and is therefore more likely to be confused with the gray's trill. A trill coming from close to the ground and interspersed with single peeps at the same pitch is coming from a spring peeper, not a gray treefrog.

Audio: Gray Treefrog call (coming soon)