10 Interesting Facts About American Green Tree Frogs

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 illuminated by their porch lights, these frogs are easily overlooked and severely undervalued.

Here are 10 interesting things you may not know about this ever-common tree frog.

1. American Green Tree Frogs Have a Wide Range

American green tree frogs can adapt to a variety of habitats, as long as they have a few key resources available. They inhabit 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 Spend Ample Time Near Water Despite Being Arboreal

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 during the 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, and cattails.

3. They Can 'Honk' 75 Times Per Minute

Green tree frogs are sometimes known as "bell frogs" because of their resounding 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 two inches of the surface. This mating call is distinct from the calls they use to defend territory or announce rainfall and can be heard by females from at least 300 yards 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

American green tree frogs are extremely lovable—and not just because of their bright green hue or their charming honk. They're also natural predators to public enemy No. 1: mosquitos.

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

5. American Green Tree Frogs Aren't Always Green

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, then return to its vivid green once it's warm and active again.

The frogs also have a white, yellow, or sometimes iridescent stripe along each side of their bodies. 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. They Breed in Accordance With Rain

Several factors determine when green tree frogs breed, including day length, temperature, and precipitation. 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 wet weather to come.

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 to more than 2,000.

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

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 a species of least concern by the IUCN, which notes its population is large, stable, and widespread. The species isn't known to face any major threats.

9. They Are Adaptable

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. American Green Tree Frogs Are Popular as Pets

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 keeping 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, admire it without picking it up.