Geographic Range
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.
Habitat
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
- Other Habitat Features
- riparian
Physical Description
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.
- Other Physical Features
- ectothermic
- heterothermic
- bilateral symmetry
- Sexual Dimorphism
- female larger
Development
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
Reproduction
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.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- oviparous
There is no parental investment beyond the efforts of mating and egg-laying.
- Parental Investment
- no parental involvement
-
pre-fertilization
- provisioning
-
protecting
- female
Lifespan/Longevity
Lifespans in the wild are unknown, but captives can live 6 years with proper care.
Behavior
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.
- Key Behaviors
- saltatorial
- motile
- sedentary
- solitary
Home Range
No information was available on green treefrog home ranges.
Communication and Perception
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.
- Perception Channels
- visual
- tactile
- acoustic
- vibrations
- chemical
Food Habits
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.
- Primary Diet
- carnivore
- Animal Foods
- insects
Predation
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.
- Anti-predator Adaptations
- cryptic
Ecosystem Roles
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.
Economic Importance for Humans: Positive
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
Economic Importance for Humans: Negative
These treefrogs have no known negative economic impacts.
Conservation Status
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.
Additional Links
Contributors
Tanya Dewey (editor), Animal Diversity Web.
Matthew Nichols (author), Radford University, Karen Powers (editor, instructor), Radford University.
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- terrestrial
-
Living on the ground.
- freshwater
-
mainly lives in water that is not salty.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- marsh
-
marshes are wetland areas often dominated by grasses and reeds.
- swamp
-
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
- riparian
-
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- heterothermic
-
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- polygynous
-
having more than one female as a mate at one time
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- external fertilization
-
fertilization takes place outside the female's body
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- saltatorial
-
specialized for leaping or bounding locomotion; jumps or hops.
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- solitary
-
lives alone
- visual
-
uses sight to communicate
- acoustic
-
uses sound to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- vibrations
-
movements of a hard surface that are produced by animals as signals to others
- chemical
-
uses smells or other chemicals to communicate
- cryptic
-
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
- carnivore
-
an animal that mainly eats meat
- insectivore
-
An animal that eats mainly insects or spiders.
- metamorphosis
-
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
References
Aresco, M. 1996. Geographic Variation in the Morphology and Lateral Stripe of the Green Treefrog (Hyla cinerea) in the Southeastern United States. American Midland Naturalist , 135/2: 293-298.
Creel, T., C. Foster, D. Forrester. 2000. Parasites of the Green treefrog, Hyla cinerea, from Orange lake, Alachua county, Florida, U.S.A.. Comparative parasitology , 67/2: 255-258.
DeGarady, C., R. Halbrook. 2006. Using Anurans as Bioindicators of PCB Contaminated Streams. Journal of Herpetology , 40/1: 127-130.
Freed, A. 1980. Prey Selection and Feeding Behavior of the Green Tree Frog (Hyla cinerea). Ecology , 61/3: 461-465.
Gunsburger, M. 2005. Differential Predation on Tadpoles Influences the Potential Effects of Hybridization between Hyla cinerea and Hyla gratiosa. Journal of Herpetology , 39/4: 682-687.
Gunzburger, M. 2005. Reprodcutive Ecology of the Green Treefrog (Hyla cinerea) in Northwester Florida. American Midland Naturalist , 155: 321-328.
Halliday, T. 1986. The Encylopedia of Reptile and Amphibians . New York, NY: Facts on File.
Horn, S., J. Hanula, M. Ulyshen. 2004. Abundance of Green Tree Frogs and Insects in Artificial Canopy Gaps in a Bottomland Hardwood Forest. American Midland Naturalist , 153: 321-326.
Linzey, D. 2001. Vertebrate Biology . New York, NY: Mcgraw-Hill.
Martof, B., W. Palmer, J. Bailey, J. Harrison III. 1980. Amphibians and Reptiles of the Carolinas and Virginia . Greensboro, NC: University of North Carolina Press.
Mitchell, J., K. Reay. 1999. Atlas of Amphibians & Reptiles in Virginia . Richmond, VA: Virginia Department of Game and Inland Fisheries.
PETCO Animal Supplies, Inc., 2004. "Green treefrog care sheet" (On-line). Accessed December 08, 2007 at http://www.petco.com/caresheets/amphibians/Treefrog_Green.pdf .
Pham, L., S. Boudreaux, S. Karhbet, B. Price, A. Ackleh, J. Carter, N. Pal. 2007. Population Estimates of Hyla cinerea (Schneider) (Green Tree Frog) in an Urban Environment. Southeastern Naturalist , 6/2: 203-216.
Saenz, D., L. Fitzgerald, K. Baum, R. Conner. 2006. Abiotic Correlates of Anuran Calling Phenology: The Importance of Rain, Temperature, and Season. Herpretological Monographs , 20: 64-82.
Walton, A. 1933. The Nematoda as Parasites of Amphibia. The Journal of Parasitology , 20/1: 1-32.