Hyla avivocaBird-voiced Treefrog

Geographic Range

The bird-voiced treefrog Hyla avivoca is most commonly found in deep wooded swamps with emergent woody vegetation in the south-eastern United States (Knapp 2001, Behler 1979).

Habitat

Bird-voiced treefrogs prefer swamps and brushy areas and are usually found in trees that grow in water. (Georgia Museum of Natural History 2000)

Physical Description

Adult length 28 mm to 51 mm (1.25 inches to 2.25 inches).

The backs of bird-voiced treefrogs are gray, brown or green, often have one or more dark spots and have a warty surface. They have light, sometimes white, spots under their eyes. They have large toe pads, with adhesive disks on the tips of their digits. The hidden surfaces of their thighs and groin area usually range from light green to white and they have dark bars on their hind legs. The species is dimorphic, females are usually larger than the males. The males range in size from 28 mm to 39 mm (1.25 inches to 1.75 inches) and the females range from 32 mm to 51 mm (1.5 inches to 2.25 inches). The males have a darker throat pouch than the females. The tadpoles, prior to metamorphosis, are black and have several orange bands on their tails and an orange spot on their heads. (Wright 1949, Northern Prairie Wildlife Research 2001, Georgia Museum 2000)

Development

Reproduction

Bird-voiced treefrogs are considered late breeders, usually breeding from June to mid-August. The eggs are layed in shallow water in packets of 6 to 15 eggs. Females lay, on average, a total of 500 to 650 eggs. The eggs will hatch into tadpoles usually within a few days. The tadpoles will develop into adults within approximately one month. The tadpoles transformed size is approximately one-half inch. Breeding is usually increased with heavy rains. (Knapp 2001, Georgia Wildlife 2000, Auburn University 2001)

Lifespan/Longevity

Behavior

Bird-voiced treefrogs are usually found in shrubs around swamps. They are nocturnal and arboreal. They descend from the trees only to breed. Males will perform their mating call perched on tree limbs 610 mm to 2440 mm (2 to 8 feet) above water. They can only be heard calling during breeding season. The call is a series of bird-like whistles, given at a rate of several per second, rapidly repeated numerous times. The call has been compared to that of whistling for a dog.(Northern Prairie Research Center 2001, Conant 1958, Behler 1979, Auburn University 2001)

Food Habits

Bird-voiced treefrogs are opportunistic feeders. Their diet consists mainly of spiders and small arboreal insects. They typically hunt for their prey by foraging about in trees and shrubs. (Illinois Department of Natural Resources 1998)

Economic Importance for Humans: Positive

By eating small insects these frogs may keep pests populations lower.

Economic Importance for Humans: Negative

None Known

Conservation Status

Bird-voiced treefrogs are classified as a threatened species in the state of Illinois. This is the northern most portion of the species' range, and these frogs occur only in a few cyprus swamps in the extreme southern tip of Illinois. It is listed as threatened because it occurs only in these few locations. Its population can be affected by any river damming or swamp drainage that causes changes to swampy land. (Georgia Museum of Natural History 2000)

Other Comments

There are two known sub-species to the Hyla avivoca, the western bird-voiced treefrog, Hyla avivoca avivoca, and the eastern bird-voiced treefrog, Hyla avivoca agechiensis. Hyla avivoca avivoca are smaller in size and has a light spot under their eyes. They are most commonly found from Illinois to Louisiana and west Florida. Hyla avivoca agechiensis is larger in size with either yellow or light green spots under their eyes. They are most commonly found in central Georgia and southwest South Carolina.

Bird-voiced treefrogs emit skin secretions that are very irritating to humans. These secretions can cause runny noses and watery eyes. (Behler 1979)

Contributors

Jessica Underwood (author), Fresno City College.

Glossary

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.

World Map

arboreal

Referring to an animal that lives in trees; tree-climbing.

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.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

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.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

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).

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.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

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.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

References

Auburn University Museum Herpetology Webpage, "Hyla avivoca Bird-voiced Treefrog" (On-line). Accessed February 28, 2001 at http://www.auburn.edu/academic/science_math/cosam/museum/herps/hyla_avivoca.html.

Behler, J. 1979. The Audubon Society Field Guide to North American Reptiles and Amphibians. New York: Alfred A. Knopf , Inc..

Conant, R. 1958. A Field Guide to Reptiles and Amphibians. Boston: Houghton Mifflin Company.

Knapp, W. December 10, 2002. "The Frogs & Toads of Georgia" (On-line). Accessed January 13, 2003 at http://wwknapp.home.mindspring.com/docs/bird.voiced.tfrog.html.

Northern Prairie Wildlife Research Center, February 23, 2001. "Bird-voiced Treefrog" (On-line). Accessed February 28,2001 at http://www.npwrc.usgs.gov/narcnext/idguide/hylaaviv.htm.

The Georgia Museum of Natural History, , Georgia Department of Natural Resources. June 1, 2000. "Bird-voiced Treefreg, Hyla avivoca" (On-line). Accessed February 27, 2001 at http://museum.nhm.uga.edu/GAWildlife/Amphibians/anura/Hylidae/havivoca.html.

Wright, A., A. Wright. 1949. Handbook of Frogs and Toads. Ithaca, New York: Comstock Publishing Associates.