Gray treefrog (Hyla versicolor)

Gray treefrog
IUCN Red List species status – Least Concern LEAST

Top facts

  • The yellow colouration of the groin and leg area of the gray treefrog functions to confuse predators and deter attacks.
  • The gray treefrog produces glycerol when it is exposed to subfreezing temperatures, which acts as natural antifreeze and prevents any cell damage from occurring.
  • The scientific name for the gray treefrog, versicolor, is derived from Latin and means ‘variable colour’, which relates to this species’ ability to change colour.
  • The pattern on the back of the gray treefrog looks very similar to encrusting lichen.
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Gray treefrog fact file

Gray treefrog description

GenusHyla (1)

A relatively large frog species, the gray treefrog (Hyla versicolor) is mainly pale to dark grey, with dark grey, brown or green pigmentation on its dorsal surface (2). The upper surface of the body also features a unique blotchy pattern (2) (3), whose appearance is often compared to encrusting lichen (3). The pattern can vary significantly, although it is usually composed of two dark, centrally located patches (2), which can be green, buff or grey (3). There is a conspicuous white spot beneath each eye (2) (3), and a dark stripe extends from the rear of the eyes to the front of the legs. The skin of the gray treefrog is coarse (2).

The gray treefrog gets its scientific name from the Latin for ‘variable colour’ due to its extraordinary ability to change the colour of its skin. The colour the individual changes to is dependent on the time of day and surrounding temperature, with the skin becoming much lighter at night and darker during the day (3).

The upper surfaces of the legs have a dark, banded pattern, which contrasts significantly with the bright yellow or orange undersides of the legs (3). This bright colouration is thought to deter predators from attacking the gray treefrog (4). The hands and feet are webbed, although the feet have more extensive webbing than the hands (3). Each digit also has an enlarged tip which produces an adhesive fluid, enabling this species to grip trees when climbing into its arboreal habitat (2) (3). The underside of the gray treefrog is white (2), although the male has a black throat which can be seen when it is calling. While the size of individuals is highly variable between geographical locations, the male gray treefrog is generally larger than the female (3).

The colour of the gray treefrog tadpole is very inconsistent, and individuals can be many different shades of brown or olive green. The body and tail are patterned with numerous black and gold specks. The tail fins may be coloured or blotchy and some may occasionally become bright red. When it is recently metamorphosed, the gray treefrog may have smooth or coarse skin which is usually green. As the individual ages it develops its adult colouration (3).

The loud, musical call of the male can mostly be heard after dusk and may persist for up to four hours (3)

Snout-vent length: up to 6 cm (2)

Gray treefrog biology

During winter, the gray treefrog hibernates within its arboreal habitat, taking refuge in tree hollows and crevices (4). Throughout this period it is extremely cold in certain parts of its range, with some areas experiencing temperatures below freezing. This highly adapted frog produces glycerol during periods of cold weather, which allows an individual to ‘freeze’ itself, while maintaining interior metabolic processes at a very slow rate (2) (3) (4).

After emerging from hibernation in early spring (3) (4), the male gray treefrog begins calling to find a mate (4), as well as to establish a breeding territory. Most reproduction takes place early in the calling season, which usually begins in late April and ends in early August (3). The male and female gray treefrog mate up to three times per season (5).

The territorial male defends its territory by fighting with other males who enter its area. Fighting between two males usually consists of 30 to 90 seconds of wrestling, shoving, kicking and head butting until the subordinate male retreats. To instigate mating, the female approaches the calling male and touches him, before rotating 90 degrees (3). Amplexus may last for several hours, although only an hour is spent depositing and fertilising the 1,000 to 2,000 eggs laid by the female (4). The male and female float on the surface of the water and the female lays the eggs in small quantities while they are fertilised by the male (3) (4). The eggs are usually divided into masses containing up to 40 eggs, which are surrounded by a transparent mucous layer (3) (4) (5). The mucous layer swells and attaches the mass to a substrate (4) (5).

The eggs of the gray treefrog hatch up to five days after deposition, although this varies depending on the water temperature (3) (4). Between 10 and 60 minutes before hatching, the embryo rotates its head against the edge of the egg and releases a fluid, which helps to break down the wall of the egg (4). The larval period usually lasts between 40 and 60 days, after which the larva metamorphoses into its adult form (3) (4). Within a week, the juvenile will have dispersed from its natal pond (5). The gray treefrog reaches sexual maturity at around two years old (3).

The diet of the gray treefrog mainly consists of spiders, mites, harvestmen, crickets, moths, roaches and other invertebrates (2) (3). This nocturnal species forages throughout the night in both low and high vegetation, which it is able to climb due to specialised adhesive pads on the tips of its digits (4).


Gray treefrog range

The range of the gray treefrog covers most of the eastern United States and southeast Canada (1) (3) (5), although its exact distribution is unknown and may be larger or smaller than estimated (1).


Gray treefrog habitat

The gray treefrog typically inhabits moist woods and forests which are close to appropriate breeding areas including freshwater ponds, puddles, bogs, swamps and marshes (1) (3) (4). During hibernation and rest, this species hides underneath tree bark, leaves, rotten logs, and in tree hollows and stumps (1) (4). When it is newly metamorphosed, the gray treefrog usually remains close to the forest floor, and moves up into the forest canopy as it ages (3). A highly adaptable species, the gray treefrog may also be found around farmland and suburban areas (4).


Gray treefrog status

The gray treefrog is classified as Least Concern (LC) on the IUCN Red List (1).

IUCN Red List species status – Least Concern


Gray treefrog threats

The gray treefrog is not thought to be globally threatened (1), although certain populations may be at risk from non-native species (1) (3), fungal diseases, road traffic accidents and habitat loss (3). Pesticide and insecticide exposure has also been found to affect local populations of this species (2) (3) (4).


Gray treefrog conservation

There are not currently known to be any conservation measures in place for the gray treefrog.


Find out more

Find out more about the gray treefrog:

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The mating position of frogs and toads, in which the male clasps the female around the back or waist.
An animal which lives or spends a large amount of time in trees.
Relating to the back or top side of an animal.
The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
A winter survival strategy in which the animal passes the winter in a resting state. This period of inactivity is characterised by specific biological and biochemical changes including lowered blood pressure and respiration rate.
Animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones) and echinoderms.
Immature stage in an animal’s lifecycle, after it hatches from an egg and before it changes into the adult form. Larvae are typically very different in appearance to adults; they are able to feed and move around but are usually unable to reproduce.
Of or relating to the immature stage in an animal’s lifecycle, after it hatches from an egg and before it changes into the adult form. Larvae are typically very different in appearance to adults; they are able to feed and move around but are usually unable to reproduce.
A composite organism made up of a fungus in a co-operative partnership with an alga. Owing to this partnership, lichens can thrive in harsh environments such as mountaintops and polar regions. Characteristically forms a crustlike or branching growth on rocks or tree trunks.
An abrupt physical change from the larval to the adult form.
Of or relating to birth.
Active at night.
Describes an animal, a pair of animals or a group that occupies and defends an area.
An area occupied and defended by an animal, a pair of animals or a group.


  1. IUCN Red List (October, 2013)
  2. Trauth, S.E., Robison, H.W. and Plummer, M.V. (2004) The Amphibians and Reptiles of Arkansas. University of Arkansas Press, Arkansas.
  3. Dodd, C.K. (2013) Frogs of the United States and Canada. Volume I. Johns Hopkins University Press, Maryland.
  4. Holman, J.A. (2012) The Amphibians and Reptiles of Michigan. Wayne State University Press, Michigan.
  5. AmphibiaWeb - Gray treefrog (October, 2013)

Image credit

Gray treefrog  
Gray treefrog

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