Tree Frog

Quick Take

• Red-eyed tree frogs use their vivid eyes as a weapon, though not in the way you would expect. See their vivid eye defense →
• One tree frog species produces a milky coating that scientists are quietly turning into medicine. Explore White's tree frog skin →
• Europeans once trusted a frog more than a weather forecast, and it actually worked. Discover the frog barometer →
• The frog sound everyone imitates on TV actually belongs to just one specific species living in one specific place. Find the iconic ribbit species →

Unlike their somewhat dumpy terrestrial counterparts, tree frogs generally have bright colors that make them a favorite zoo exhibit. Their distinctive calls often make them heard but not seen in their native habitat, as they are primarily active at night. Although these frogs live mostly in tropical climates, some species live in more temperate areas and hibernate during the winter.

5 Incredible Tree Frog Facts

• In Europe, these frogs were historically seen as barometers because they would respond to approaching rain by calling.
• Most of these frog species can change skin color, sometimes in response to their mood, shifting among a range of green, gray, brown, and yellow hues.
• White’s tree frogs have a strong sense of hearing and can sense vibrations through the ground.
• Red-eyed tree frogs are considered to be the ambassadors of these frog species because of their strikingly vivid eyes.
• These frogs have an additional eyelid that veils their eyes. They also blink when swallowing to force down their prey.

Scientific Name and History

Tree frogs comprise several families of the order Anura. Those in the family Hylidae and the genus Hyla are sometimes called true tree frogs and are the most numerous. Nonhylid tree frogs incorporate the families Centrolenidae, Hyperoliidae, Rhacophoridae, and Microhylidae.

Frogs have lived on Earth for over 200 million years. There is fossil evidence that the red-eyed tree frog has remained much the same for more than 10 million years. The reason there are so many different species from several different biological families is a process called convergent evolution — that is, similar living conditions caused them to evolve to look very similar.

To the ancient Egyptians and Mesopotamians, frogs symbolized fertility, while to the ancient Greeks and Romans they represented not only fertility but also harmony and licentiousness. Frogs have been popular characters in folklore and fairy tales, including the frog that turned into a prince when kissed by the fair maiden.

Types of Tree Frogs

Although there are far too many types of tree frogs to name here, a few notable ones include:

• White-lipped tree frog: largest, lives in Australia and Oceania.
• Cuban tree frog: largest in the Western Hemisphere, lives in the Caribbean and southeastern U.S.
• Red-eyed tree frog: flashing, bulging eyes; has remained relatively unchanged for 10 million years; lives in southern Mexico, Central America, and northern South America.
• Green tree frog: bright green, uses a variety of barking calls for communication.
• White’s tree frog (aka dumpy tree frog or Australian tree frog): encase their bodies in a cavity to preserve moisture, live in Australia and New Guinea.
• Gray tree frog: lives in North America.
• Little grass frog: smallest of all tree frogs, lives in cypress swamps of Virginia, Florida, and Alabama.
• Boophis tree frog (aka bright-eyed or skeleton): the only genus in the subfamily Boophinae; lives on Madagascar and Mayotte Island.
• Other notable species include the European green frog, the spring peeper, the pine barren tree frog, the Borneo-eared tree frog, Cope’s gray tree frog, and the Pacific tree frog — the one responsible for the famous “ribbit” sound attributed to all frogs on TV and in movies.

Appearance

The most distinguishing feature of the tree frogs is their feet, as the last bone in their toes is claw-shaped. Toe pads with tiny suction cups and extraskeletal structures on their toes also help them climb trees. They come in a variety of colors, most commonly green, gray, or brown.

Because of their primarily arboreal habitat — living on leaves and small branches — most of these frogs are small and typically more slender than terrestrial frogs. The smallest species are less than an inch in length.

The largest of these frogs are the white-lipped tree frog found in Australia and Oceania, ranging from four inches to 5.5 inches long. The largest species in the Western Hemisphere is the Cuban tree frog, found in the Caribbean and the southeastern United States, with a length of 2 to 5.5 inches. It is brown and somewhat bland and dumpy in appearance.

As one of the most striking members of the Hylidae family, red-eyed tree frogs may have developed their bright eyes, in part, so that predators may question their meal choice and go for less intimidating prey. Another adaptation, called startle coloration, allows red-eyed tree frogs to flash their bulging eyes and reveal webbed orange feet and their bright blue-and-yellow flanks, often causing birds and snakes to stop in surprise, which giving the frog time to flee. Their bright green color may also overstimulate predators’ eyes by creating a confusing ghost image.

American green tree frogs are bright green, which helps them camouflage in surrounding foliage in the wild. They have a light white or cream-colored stripe from the side of the head down to their flanks.

White’s tree frogs encase their bodies in a milky white coating called caerulein that helps them survive in dry areas by conserving body moisture. Scientists have used extracts from their skin for medicines that fight staphylococcus bacteria, lower blood pressure, and treat cold sores caused by the herpes virus.

Behavior

Most species are nocturnal and solitary but will gather in large groups during mating season. Many spend their days sleeping on leaves and branches. In hot summer months, White’s tree frogs often go looking for water in people’s homes. When threatened, they emit an ear-piercing scream. Green tree frogs use a variety of barking calls for communication. Adults will frequently camouflage themselves in vegetation by tucking in their legs and closing their eyes.

Habitat

Tree frogs live on every continent except Antarctica, with the highest concentration in Central and South America, where you will find about 600 species. About 30 species live in the warmer regions of the southeastern United States. Most, but not all, species are arboreal, which is why they have long legs and toe pads to help them climb and jump. Non-arboreal species live in lakes and ponds or among moist ground cover.

Red-eyed frogs live in tropical lowlands from southern Mexico, through Central America and into northern South America. They are nocturnal, hiding in the rainforest canopy.

An adaptable species called White’s tree frog lives in Australia and New Guinea. They prefer moist forests and typically do not live near bodies of water, instead collecting rainwater that pools on leaves and in cup-shaped plants and crevices. This species’ adaptability allows them to live in suburban and agricultural areas near people, and they are commonly found in bathrooms, water tanks, and reservoirs.

Diet

Like other amphibians, these frogs are carnivores, eating insects like crickets and flies, worms, spiders, moths, and other invertebrates. The large Cuban frog will eat anything that will fit in its mouth, including lizards, snakes, small mammals, and even other frogs. These frogs ambush their unsuspecting prey with their long, sticky tongues.

Predators and Threats

Predators include a variety of mammals, reptiles, birds, and even some large fish, primarily due to the frogs’ small size. The official conservation status of these frogs is listed as Least Concern, because of their wide distribution and assumed large population. Nevertheless, these frogs face threats to their overall population, including habitat destruction by humans, pollution, climate change, and disease. Habitat destruction is a concern in Europe, although conservation efforts in several European countries have successfully rebuilt some tree frog habitats.

Reproduction, Babies, and Lifespan

The males of almost every species attract mates via barking calls, with each tree frog type having its own unique call.

Some hatch as miniature adults, but more commonly these frogs hatch as tadpoles that develop into adults. Females lay eggs on leaves above water, allowing hatched tadpoles to drop into the water to develop. The metamorphosis from tadpole to adult can take a few weeks to a few months.

White’s tree frogs begin to reproduce in their second year and often fast for several days before mating. Males develop a black pad on their thumbs to help grip females during mating. Clutch size varies according to species and can contain 150 to 1,000 eggs, with hatching beginning about 28 to 36 hours after laying.

Lifespan varies among species, with some living less than three years. Gray tree frogs in North America live about five years, while the Australian tree frog can live as long as 15 years in captivity. White’s tree frogs generally live about 16 years but have lived as long as 21 years in captivity.

Population

Scientists have no real estimate of the worldwide population of these frogs as they are widespread and are not endangered. However, their populations are thought to be declining as humans continue to encroach on their habitats.

In the Zoo

The Smithsonian National Zoo in Washington, D.C., keeps red-eyed tree frogs along with White’s tree frogs. Both species receive a diet of crickets, cockroaches, and worms. The best time to see these frogs in the zoo is in the early morning and late afternoon. They are primarily nocturnal creatures, so most of the time, visitors will see them sleeping on top of green leaves in their exhibit. You’ll have to look carefully, though, as these frogs tend to blend in with their environment.