10 Interesting Facts About American Green Tree Frogs

They're abundant, adaptable, and have an appetite for mosquitoes.

American green tree frog
The American green tree frog occurs across a swath of the U.S. Southeast.

kristianbell / Getty Images

The American green tree frog is a staple of summer nights in the U.S. South, where its groaning call echoes through countless swamps, forests, fields, and backyards. Yet even for many people who share their habitats, hear them sing, and sometimes see them by their porch lights, these frogs are easily overlooked and undervalued.

Here are a few interesting things you may not know about green tree frogs.

1. They Have a Wide Range

An American green tree frog perched in sunlight in Illinois
An American green tree frog at Shawnee National Forest in southern Illinois. Greg Schechter / Flickr / CC BY 2.0

American green tree frogs can adapt to a variety of habitats, as long as they have a few key resources available. They range along the Atlantic and Gulf coasts from Delaware to South Florida to South Texas, and inland as far as Oklahoma, Missouri, and southern Illinois.

The American green tree frog is the official state amphibian for both Louisiana and Georgia, two states where it is widespread.

2. They Live in Arboreal Habitats

As their name suggests, green tree frogs are largely arboreal (tree-dwelling). Yet while they spend much of their lives in trees, they also need clean water, especially in breeding season. The species is commonly found near ponds, lakes, streams, marshes, and other wetlands, where they seem to prefer habitats with lots of floating plants (like lily pads and duckweed), grasses, or cattails.

3. They Can 'Honk' 75 Times Per Minute

Green tree frogs are sometimes known as "bell frogs" in honor of their advertisement call (or mating call), which is an abrupt nasal honk or bark repeated up to 75 times per minute.

During the breeding season, roughly March to October, males often congregate to sing from weedy, watery habitats, typically perched on floating vegetation or other plants within about 2 inches (5 cm) of the surface. This mating song is distinct from their other calls, which serve purposes like defending territory or announcing rainfall, and can be heard by females from at least 300 yards (274 meters) away.

Listen to an American green tree frog's mating call on the National Park Service's sound gallery.

4. They Provide Free Pest Control

Green tree frogs are insectivores, so their survival depends on their ability to find enough flies, mosquitoes, and other small insects to eat. Not only are many pesticides directly toxic to frogs, sometimes killing them with alarming speed, but they can also indirectly threaten the amphibians by choking off their food supply.

The species poses no known negative effects for humans, and it can benefit us with its appetite for troublesome insects like mosquitoes.

5. They Aren't Always Green

green tree frogs, brown in color, resting on the ground
Green tree frogs often become more brown or gray while inactive during cooler, drier weather. Judy Gallagher / Flickr / CC BY 2.0

The skin of an American green tree frog is usually lime green, but it can vary in color depending on the animal's activity. A green tree frog may look olive green, brown, or gray when cool and resting, but then return to its vivid green color once it's warm and active again.

The frogs also have a white, yellow, or sometimes iridescent stripe along each side of their body, although the length of these stripes varies among populations, and some green tree frogs don't have them at all. Some also have yellow or golden flecks overlaying the green color of their backs.

6. Their Lives Revolve Around Rain

A green tree frog on a log in a forest in North Carolina
Green tree frogs tend to be energized by recent rainfall. NC Wetlands / Flickr / public domain

Several factors determine when green tree frogs breed, including day length, temperature, and precipitation. Rainfall seems to be especially significant, as the species generally breeds after rainfall. And while the relative importance of these factors isn't well understood, the species generally breeds after rainfall.

Rain is so important, in fact, the frogs have developed a "rain call" that's distinct from their mating or alarm calls. Some people even refer to the species as "rain frogs," and consider them good predictors of rainy weather.

7. They Lay Hundreds of Eggs at a Time

Once a female frog has responded to a male's calls and he has fertilized her eggs, she deposits her clutch in shallow water among aquatic plants. The size of that clutch can vary widely, but it often features several hundred eggs. The average number of eggs can range from about 700 (southern Illinois) or 800 (Georgia) as high as 2,100 (Arkansas).

The fertilized eggs will hatch after about a week, and the tadpoles will complete their metamorphosis into frogs within about a month.

8. They Are Abundant

green tree frog on a screen window
Green tree frogs often capitalize on electric lights to help them hunt insects at night. Rusty Clark / Flickr / CC BY 2.0

Although many frogs and other amphibians are currently in decline around the world — a crisis fueled largely by habitat loss, invasive species, and disease — the American green tree frog seems to be an exception. It's listed as Least Concern by the International Union for Conservation of Nature (IUCN), which notes its population is large, stable, and widespread, and the species isn't known to face any major threats.

9. They Are Adaptable

green tree frog calling from a tree branch
Some green tree frogs alter their calls when faced with acoustic competition. Clinton & Charles Robinson / Flickr / CC BY 2.0 

Green tree frogs do face some threats, though, and while the species may enjoy relative stability overall, some populations are safer than others.

In Florida, for example, green tree frogs are one of several native species to face growing competition from Cuban tree frogs, an invasive species native to Cuba, the Bahamas, and the Cayman Islands. Not only do Cuban tree frogs outcompete and sometimes eat native tree frogs, but they also produce calls with similar timing and pitch to those of green tree frogs, threatening the native species with a new source of acoustic competition.

At least some green tree frogs may be adapting to this threat. When their habitat is invaded by Cuban tree frogs, green tree frogs respond by modifying their own calls to be shorter and louder.

10. They're Popular As Pets, But It's Better to Admire Them From Afar

American green tree frogs are small, charismatic, and relatively easy to care for, making them popular as pets. However, the pet trade can be hazardous for frogs in general, helping spread deadly pathogens like chytrid fungi. Anyone considering a pet frog should be diligent about its origins, and you should never take a frog from the wild. If you do commit to a frog as a pet, try to find one that was locally bred in captivity.

Green tree frogs are generally timid and do not tolerate much handling, which can both stress them out and increase their risk of illness. They may be easy to care for, but they are not the cuddliest of pets. If you find one in the wild, whether in the backcountry or your backyard, try to admire it without picking it up.