American green treefrog

American Green Tree Frog

What it is

The American green tree frog, scientifically known as Dryophytes cinereus (formerly Hyla cinerea), is a common species of New World tree frog. It is a member of the Hylidae family and is characterized by its moderately sized, slender body, long legs, and bright green to reddish-brown coloration. Sometimes, light yellowish spots are present on its dorsum. This species is primarily nocturnal and insectivorous.

Distribution and Habitat

This frog is indigenous to the central and southeastern United States, with a geographic range extending from the Eastern Shore of Maryland to southeast Florida, and populations as far west as central Texas. They are found in coastal plains and prefer open canopy forests with permanent water sources and abundant vegetation. Common habitats include cypress ponds, water lily prairies, and marshes. The American green tree frog is also adaptable, frequently being sighted in suburban environments such as backyards with ponds or garden structures.

Description and Behavior

The American green tree frog has smooth skin, large, protruding eyes with horizontal pupils, and ranges from 3.2 to 6.4 centimeters in length. Its coloration can vary, potentially leading to confusion with other species, and some evidence suggests it can change color in response to background or temperature. They are ectothermic and heterothermic. As a small and easily frightened species, they do not tolerate frequent handling well. They are arboreal, using toe pads to cling to vertical surfaces, and are most active at night. When defending territory, they may emit aggressive calls or engage in grappling.

Diet

Primarily insectivorous, the American green tree frog consumes a variety of small invertebrates including flies, mosquitoes, grasshoppers, cockroaches, spiders, beetles, and ants. Prey selection appears to be influenced by activity levels, with more active prey being favored. Ambush-style foraging is common, with most prey taken at night. It is also noted that they may ingest plant material.

Breeding and Reproduction

Male American green tree frogs attract females with low-frequency advertisement calls. Breeding occurs through amplexus, and males compete for mates by adjusting their call timing or using 'satellite' tactics to intercept females. Females lay clutches of eggs, typically around 400 eggs, in permanent bodies of water. Clutch size is positively correlated with female size. Breeding is strongly influenced by environmental factors such as day length, temperature, and precipitation, generally following rainfall.

Conservation and Threats

The American green tree frog faces threats from habitat loss due to urbanization and wildfires. Increased salinity and pesticide concentrations in their wetland habitats negatively impact reproductive success. Tadpoles are preyed upon by sunfish, bass, and dragonflies, while adults are predated by snakes, birds, and other frogs. Interestingly, this species is not easily susceptible to the chytridiomycosis pathogen, though the reasons for this are not fully understood.

Role as Bioindicators

Due to their permeable skin, American green tree frogs can absorb synthetic compounds from their aquatic environments, making them valuable bioindicators for measuring aquatic contamination, particularly from pesticides like polychlorinated biphenyls.