Tree Frog, Green


Hyla cinerea


Adult length: 1.26 to 2.52 in (32 – 64 mm); coloration and appearance: bodies are usually green in shades ranging from bright yellowish olive to lime green; darkness of the color changes with lighting or temperature; there may be small patches of gold or white on the skin, and may have a white, pale yellow, or cream-colored line running from the jaw or upper lip to the groin; abdomen is pale yellow to white; skin is smooth; toes have large pads. Males have wrinkled throats (indicating the vocal pouch) and are slightly smaller than females.

Family

Hylidae

Order

Anura

Class

Amphibia

Range

Southeastern US: Florida, Alabama, southern Georgia, Louisiana, Delaware, eastern Maryland and Virginia, eastern North and South Carolina, eastern Texas, and areas extending along the Mississippi Valley to southern Illinois.

Habitat

Wetlands, including lakes, ponds, floodplain sloughs, cattail marshes, and bald cypress swamps.

Life Expectancy

In the wild: unknown; in captivity: up to 6 years

Sexual Maturity

2 years of age

Diet

In the wild, they eat a variety of insects and other small invertebrates; in the Zoo, they are fed crickets, and occasionally waxworms.

Status

IUCN – Least Concern

Behaviors

Green treefrogs are mobile and can be found in large groups during the breeding season, especially during peak times. They make small scale movements between foraging and breeding areas seasonally. Besides their mating calls, alarm and rain calls are important aspects of social behavior. During most of the year green treefrogs are solitary. They are most active when the weather is moist. The mating season takes place from mid-April to mid-August. Breeding is strongly influenced by day length, temperature, and precipitation. The relative influence of these factors is not well understood, but these frogs generally breed following rainfall. Males tend to call more frequently as temperature and day length increases. To attract mates, males use a distinct advertisement call which is noticeably different than release or warning calls. Once the male has attracted an appropriate mate they begin amplexus, with the male tightly grasping onto the female to bring their cloacal openings close together for fertilization. Males generally try to mate with as many females as they can attract. Females lay eggs in shallow water, which attach to the roots of aquatic plants. Average clutch size in a Florida population of green treefrogs was observed to be approximately 400 eggs. Although many females may only lay a single clutch in a season, some have been known to lay multiple clutches. Female size was positively correlated with clutch size, but after the initial clutch the number of eggs nearly always decreased. Embryos hatch within a week and tadpoles metamorphose 28–44 days after hatching. Juveniles are often found in emergent vegetation in and around breeding ponds, though they may also migrate to adjacent uplands. Weather conditions influence breeding, which often takes place when raining, and the frogs are often seen during and after a rainstorm. Green treefrogs use a variety of calls to communicate. Males attract females through a specific mating call. Alarm calls are used to broadcast that there is an immediate threat or predator around. There is also a noticeably different rain call, which is vocalized when frogs sense that there will soon be rain.

Adaptions

Green treefrogs have well developed hearing and can sense vibrations through the ground. The parietal organ, located on the top of the head between the eyes, has been implicated in compass orientation and thermoregulation. Green treefrog adults are exceptionally good at hiding on grasses and other vegetation. When they tuck in their legs and close their eyes they blend in with the color of leaves.

Special Interests

Adult green treefrogs are subject to predation by a wide variety of organisms. Snakes, birds, large fish, and even other frogs may prey on Hyla cinerea. Green treefrogs are one of the only species in the genus Hyla in the southeastern United States that typically breeds in areas with large predatory fish. Tadpoles are at even more risk than adults because they have few defensive mechanisms and are easily caught. Predatory aquatic insects such as giant water bugs (Belastomatidae) frequently feed on tadpoles in their early stages as well as smaller fish such as pumpkinseed sunfish (Lepomis gibbosus) and bluegill sunfish (Lepomis macrochirus). Although green treefrogs are not considered a keystone species, they play a vital role in the ecosystems they inhabit. They are prey to large predatory fish, snakes, and their other predators and green treefrog adults consume large quantities of insects. Green treefrog parasites in a Florida population include the nematode Cosmocercella haberi (23% of individuals), a protozoan in the genus Opalina (47% of individuals), a trematode Clinostomum attenuatum (2% of frogs), and a nematode in the genus Rhabdias (5%). Another study found that Agamascaris enopla is an internal nematode parasite.

Folklore

Because they often appear or are heard during rain storms, folklore and legends regard these frogs as “weather prophets”.

Conservation

Green treefrogs are common throughout their geographic range. Populations are relatively large and stable at this time. Since they are reliant on aquatic habitats that are frequently destroyed by human activities. Habitat destruction and pollution will impact their numbers. There is one report of a localized population decline in Florida, and reports of recent range expansion in Illinois, Missouri, and South Carolina. It is listed as Least Concern in view of its wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. There are no major threats to this species. It is sometimes found in the international pet trade but at levels that do not currently constitute a major threat.

Jacksonville Zoo History

Part of our animal collection from 1990 to 1992 and 2000 to 2002, the green tree frog once again became part of our collection in 2007.

Exhibit

Wild Florida