This moderately large North American frog is a wide-ranging species. The males are usually slightly smaller than the females. A pointed snout and flat head possessing two transverse rows of vomerine teeth are also observed. The toe pads on Hyla cinerea are large. The hind feet display extensive webbing and have two metatarsal tubercles between the toes. Some populations have individuals that lack lateral stripes, but normally H. cinerea exhibits a lateral white or yellow stripe from the jaw to the thigh on either side of the body. White or yellow spots are often scattered on the back. The external, subgular vocal sac is mostly white or yellow in males when not inflated. During breeding season, the sides of the sac may turn green.
The size of tadpoles ranges from 4.5-5.5 mm from hatching and may grow to 60 mm before metamorphosis in a 28-44 day span. Until tadpoles reach stage 25 or 26, they display continuous ontogenetic color changes. After this period, the body turns green and the venter turns yellow. The tail may have distinct yellow orbitonasal stripes, and dark mottling or reticulations. Large tadpoles sometimes retain the yellow interorbital stripe. A long tail, bulging lateral eyes, dextral anus and sinistral spiracle are other morphological features of the tadpole from this species. Adults of this species normally turn to an ashen gray color when in preservative. The normally unobserved dorsolateral stripes in living species also appear over the subcutaneous insertions of lymph-sac septa. After months in preservation, H. cinerea displays a mostly dark green or brownish color (Conant and Collins 1998).
Hyla cinerea is commonly found in the central to southeastern United States. Its geographic range stretches from Virginia's eastern shore to the southeast tip of Florida and as far west as central Texas. Green treefrogs can be found as far north as Maryland and Delaware. Despite being considered monotypic, clinal variation of Hyla cinerea has been observed from Florida north along the Atlantic Coastal Plain as a possible result of strong selection and/or drift.
Biogeographic Regions: nearctic (Native )
endemic to a single nation
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) Range extends from Delaware south to southern Florida along the Coastal Plain, west to south-central Texas; north from the Gulf Coast to southeastern Oklahoma, southeastern Missouri, southern Illinois, southern Indiana, western Kentucky, western Tennessee, and northern Alabama. Isolated introduced population in south-central Missouri (Johnson 2000); also introduced in northwestern Puerto Rico (Isabela-Aguadilla area); Brownsville, Texas; and possibly a coastal island in Florida (see Redmer and Brandon 2003). Introduced population in eastern Kansas is apparently extirpated (Collins 1993). Native/introduced status in Indiana is uncertain (Lodato et al. 2004). Tadpoles of this species sometimes appear in new areas as a result of being incidentally stocked with gamefishes (J. Jensen, pers. comm., 2001).
Distribution and Habitat
The habitats most likely to house H. cinerea are swamps, sloughs and weedy margins of lakes and ponds. The lower Atlantic and Gulf Coastal Plains and the lower Mississippi River drainage are ideal locations of the species' environment (Connant and Collins 1998) . The range in the Mississippi River extends from Louisiana and Mississippi to the floodplains of southern and eastern Arkansas, western Tennessee and Kentucky. Southeastern Missouri and southern Illinois are also in this range. The Atlantic/Gulf Coastal range extends from the Chesapeake Bay and Virginia to the Carolinas, Georgia, and Florida. Most of Alabama, Mississippi and all of Louisiana complete the range. Introduced populations of this frog have been documented in Puerto Rico (Hedges 1996; 1999; Powell et al. 1996; Rivero 1998; Schwartz and Thomas 1975; Schwartz and Henderson 1985; 1991) , central Missouri (Johnson 2000) , a coastal island in Florida (Smith et al. 1993), and in Brownsville, Texas (Conant 1977; Smith and Kohler 1977). A population in east central Kansas that was once introduced to a fish farm has most likely been extirpated (Collins 1993).
Green treefrogs are long-legged and smooth-skinned treefrogs. Most individuals have a bright yellow-green dorsum, but individuals that are reddish-brown to green are also common. Their dorsum frequently has small golden spots which overlay the green color. Ventrally, they are white to cream and have a similarly-colored prominent lateral stripe on each side. Total length ranges from 34 to 62 mm, females tend to be larger than males.
Range length: 32 to 64 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
Length: 6 cm
Catalog Number: USNM 26291
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Year Collected: 1899
Locality: Four-Mile Run, Fairfax, Virginia, United States, North America
Green treefrogs are frequently found in small ponds, large lakes, marshes, and streams. They prefer habitats with plentiful floating vegetation, grasses, and cattails. One study suggested that, in an artificial hardwood forest setting, the abundance of Hyla cinerea is related to the openness of the forest canopy. The study noted that 88% of 331 individuals were found in areas of the forest where the canopy was open. The presence of green treefrogs in the open canopy areas was interpreted as a method for finding prey, which concentrate in sunny areas with dense ground vegetation.
Habitat Regions: temperate ; terrestrial ; freshwater
Terrestrial Biomes: forest
Aquatic Biomes: lakes and ponds; rivers and streams
Wetlands: marsh ; swamp
Other Habitat Features: riparian
Habitat and Ecology
Comments: Green treefrogs inhabit swamps, marshes, and areas adjacent to ponds, lakes, and slow streams, particularly where aquatic habitats include abundant floating and emergent vegetation. Little is known about the habits of green treefrogs outside the breeding season; they may overwinter in upland situations near wetlands. Eggs and larvae develop in shallow, still, permanent or long-lasting temporary water. Males call while perched on plants next to water or while sitting on floating plants.
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Green treefrogs are insectivores that commonly consume flies, mosquitoes, and other small insects. Freed (1980) suggested that prey were not selected by size, but according to their activity; the most active prey were the most frequently eaten. According to Freed, nearly 90% of Hyla cinerea prey were actively pursued, the other 10% were insects walking or close enough to be snatched up by the frog's tongue.
Animal Foods: insects
Primary Diet: carnivore (Insectivore )
Comments: Metamorphosed frogs eat various small invertebrates (mostly insects) obtained while climbing in vegetation or sometimes near lights at night. Larvae eat suspended matter, organic debris, algae, and plant tissue.
Although green treefrogs are not considered a keystone species, they play a vital role 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 nemaode parasite.
- Cosmocercella haberi
- Clinostomum attenuatum
- Agamascaris enopla
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). 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.
- many birds that hunt in aquatic systems (Aves)
- bluegill sunfish (Lepomis macrochirus)
- pumpkinseed sunfish (Lepomis gibbosus)
- other species of predatory fish (Actinopterygii)
- larger frogs (Rana)
- snakes (Serpentes)
Anti-predator Adaptations: cryptic
100,000 to >1,000,000 individuals
Comments: Total adult population size is unknown but surely exceeds 100,000. Common to abundant in suitable habitat in Texas; a common "backyard" species in much of eastern Texas and in Florida (Bartlett and Bartlett 1999). Common to abundant throughout the coastal plain in Alabama (Mount 1975).
Life History and Behavior
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. 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.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical
Comments: Green treefrogs are most active on warm nights, especially in association with rain, and often are inactive during the colder months, especially in the north.
Green treefrogs develop similarly to other anuran species. Eggs hatch at about 5 days post-fertilization. The first tadpole stage occurs directly after hatching. During this stage, tadpoles are very small and feed on the remainder of their yolk. Several days after hatching external gills become functional and they begin to graze on microscopic vegetation. Soon after external gills become functional they begin to disappear as the operculum develops and covers over them. Three weeks after hatching external gills have disappeared and internal gills become the primary mode of respiration. Eight to ten weeks after hatching, the front and rear legs begin development. Tadpoles also transition to a carnivorous diet at this point. In the final weeks of development the front and rear legs become fully functional and the tail starts to shorten. At this time green treefrogs are ready to leave the water and venture onto land.
Development - Life Cycle: metamorphosis
Lifespans in the wild are unknown, but captives can live 6 years with proper care.
Status: captivity: 6 (high) years.
Lifespan, longevity, and ageing
Breeding is strongly influenced by day length, temperature, and precipitation. These 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.
Mating System: polygynous
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. In the Florida population, advertisement calls of males were documented between March and September and pairs in amplexus were observed between April and August. There is some evidence to suggest that breeding season length is correlated with latitude; breeding season length decreases as latitude increases because of temperature limitations.
Breeding interval: Most females breed once yearly, although some have several clutches during the breeding season.
Breeding season: Breeding occurs from March to September.
Average number of offspring: 400.
Range time to hatching: 4 to 14 days.
Average time to hatching: 5 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
There is no parental investment beyond the efforts of mating and egg-laying.
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female)
Breeding occurs in spring or early summer (mainly April-August). Hundreds of adults may aggregate at breeding pools. Individual females divide one or more clutches of several hundred eggs among multiple clusters. Larvae hatch in a few days, often shelter and feed among dense floating vegetation, and metamorphose in a couple months, by the end of summer (often July-August).
Molecular Biology and Genetics
Barcode data: Hyla cinerea
No available public DNA sequences.
Download FASTA File
Statistics of barcoding coverage: Hyla cinerea
Public Records: 1
Specimens with Barcodes: 5
Species With Barcodes: 1
Green treefrogs are common throughout their geographic range. Populations are relatively large and stable at this time. Although, like all frog species, they are reliant on aquatic habitats that are frequently destroyed by human activities. They are listed as a species of Least Concern on the IUCN list.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Intrinsic Vulnerability: Moderately vulnerable
Environmental Specificity: Moderate to broad.
Global Short Term Trend: Relatively stable (=10% change)
Comments: Population trend is unknown but probably relatively stable.
Global Long Term Trend: Increase of 10-25% to decline of 30%
Comments: Likely relatively stable in extent of occurrence, probably less than 25% decline in population size, area of occurrence, and number/condition of occurrences, but few data available. At the margin of the range in southeastern Missouri, swamp and marsh drainage and stream channelization have destroyed a large portion of the suitable habitat (Johnson 2000).
This species appears to be more resilient and opportunistic than are many amphibians and has expanded its breeding range into many areas where ponds suitable for breeding recently have been created by humans or rebounding populations of beavers (B. Rothermel, in Jensen et al. 2008).
Life History, Abundance, Activity, and Special Behaviors
A series of nasal barks described as sounding like "frank frank frank" or "quonk quonk quonk" have been observed as breeding vocalizations. A complete reference of breeding vocalizations may be found in the Catalogue of American Amphibians and Reptiles.
Life History, Abundance, Activity, and Special Behaviors
Many human activities negatively impact the populations and habitat of this species. Among the activities are the creation of artificial lakes/ponds (Platt et al. 1999; Redmer et al. 1999), fish introductions (Bancroft et al. 1983; Redmer et al. 1999), highway traffic noise (Barrass 1986), silver nitrate used in marking individuals (Thomas 1975), timber harvest (Hanlin et al. 2000; Phelps and Lancia 1995) and the introduction of the Cuban Treefrog (Wilson and Porras 1983).
Relevance to Humans and Ecosystems
These treefrogs have no known negative economic impacts.
Green treefrogs and other anurans impact populations of mosquitoes and other small insects through predation. They can also be bioindicators of aquatic contamination, including contamination by many synthetic compounds used in pesticides, herbicides, and medications. For example, polychlorinated biphenyls (PCBs) have a high affinity for fat and are easily introduced through the digestive system. PCBs continue to accumulate with repeated exposure and should increase with organisms that have more fat. The thin, permeable skin of anurans puts them at a higher risk because compounds are so easily absorbed. Tadpoles and metamorphs are considered to be good indicators of PCB accumulation in sediment because they are usually in more direct contact with contaminated sediment. Adults are considered to be general indicators of contaminated areas but not specific conditions.
Positive Impacts: research and education; controls pest population
American green tree frog
The American green tree frog, Hyla cinerea, is a common species of New World tree frog belonging to the genus Hyla. A common backyard species, it is popular as a pet, and is the state amphibian of Georgia and Louisiana.
The frog is green, medium-sized, and up to 6 cm (2.5 in) long. Their bodies are usually green in shades ranging from bright yellowish-olive to lime green. The color can change depending on lighting or temperature. Small patches of gold or white may occur on the skin, and they may also have a white, pale yellow, or cream-colored lines running from their jaws or upper lips to their groins. They have smooth skin and large toe pads. Their abdomens are pale yellow to white. Males have wrinkled throats (indicating the vocal pouch) and are slightly smaller than females.
Distribution and habitat
These frogs are found in the central and southeastern United States, with a geographic range from the Eastern Shore of Virginia to southeast Florida, with populations as far west as central Texas, and as far north as Maryland and Delaware. The frogs are considered monotypic, but clinal variation has been observed from Florida north along the Atlantic coastal plain. This possibly may be attributed "to the result of strong selection and/or drift."
Green tree frogs "prefer habitats with plentiful floating vegetation, grasses, and cattails" and are often found in "small ponds, large lakes, marshes, and streams also can be found at night in a backyard swimming pool.
Because these frogs are small and easily frightened, they often do not do well with frequent handling. Some specimens do seem to tolerate occasional handling, however, so handling frequency should be determined on an individual basis. The little frogs tend to be nocturnal, and in captivity they will be the most active once the lights are off. Males frequently call most of the year, especially after being misted in the tank.<http://lllreptile.com/info/library/animal-care-sheets/amphibians/-/green-tree-frog/>
Most American green tree frog females breed once per year, but some have multiple clutches in a single mating season. In a Florida population, "advertisement calls of males were documented between March and September and pairs in amplexus were observed between April and August." In the Florida population, the average number of offspring in a single clutch was observed to be about 400 eggs. Eggs take between four and 14 days to hatch, with an average of five days. According to the Animal Diversity Web at the University of Michigan Museum of Zoology, "Female size was positively correlated with clutch size, but after the initial clutch, the number of eggs nearly always decreased."
Breeding is known to be strongly influenced by day length, temperature, and precipitation." While "the relative influence of these factors is not well understood," it is known as the frogs generally breed following rainfall, and males call more frequently as temperature and day length increase. Some evidence demonstrates the length of the breeding season length is correlated with latitude, with season length decreasing as latitude increases due to temperature limitations.
Males use a distinct advertisement call, "noticeably different than [sic] release or warning calls," to attract mates. Once a mate has been attracted, the pair begins amplexus, in which "the male tightly grasps onto the female to bring their cloacal openings close together for fertilization." Males are polygynous, generally seeking to mate with as many females as they can attract.
American green tree frogs are insectivores, usually consuming flies, mosquitoes, and other small insects such as crickets. One study suggested the frog selects prey not by its size, but according to its activity level, with the most active prey being the most frequently eaten. The same study showed "nearly 90% of Hyla cinerea prey were actively pursued," with the other 10% being "insects walking or close enough to be snatched up by the frog's tongue."
The frogs are popular pets because of their small size, appearance, and the undemanding conditions needed to take care of them. Unlike many amphibians, they do not require artificial heating. They need a large (at least ten-gallon) terrarium and do best with a substrate that will hold some humidity, such as commercial shredded bark or coconut husk bedding, or untreated topsoil on the floor of their terrarium. Tree frogs are arboreal, so the height on the tank is more important than the length. A variety of things for climbing, such as plants or branches, should be in the habitat. A shallow water dish should be included. Captive frogs should not be handled any more than necessary; when necessary, clean gloves should be worn.
Names and Taxonomy
Comments: According to Duellman (1993), the name should be changed from HYLA CINEREA (Schneider, 1792) to "HYLA CINERA (Schneider, 1799)," following Dubois ("1986," Alytes 5:130).