Red-Eyed Tree Frog (Agalychnis callidryas): Facts and Habitat

What does a red-eyed tree frog look like?

The red-eyed tree frog is built for life in the leaves. Its back is a bright leaf green, sometimes with a few small white spots, and its smooth skin helps it blend into foliage. The belly is white to cream. Along each flank runs a pattern of blue to purplish bars edged with yellow or cream, and the upper legs carry the same blue color.

The most famous features are the eyes. They are large, bulge from the sides of the head and have a bright red iris with a vertical, slit-shaped pupil, a typical trait of night-active frogs. When the frog rests, it covers them with a translucent lower eyelid patterned with fine golden lines, so a sleeping frog looks almost entirely green.

The feet are orange to reddish and end in round, sticky toe pads. The hands and feet are partly webbed, and the long, thin limbs let the frog reach between twigs and leaves. Color details vary across the range: in parts of Costa Rica and Panama, for example, the flanks can be blue, orange or purplish. Young froglets are brown or tan with yellowish eyes and turn green with red eyes as they grow.

How big is a red-eyed tree frog?

This is a small frog. Frog length is measured from snout to vent (the rear opening of the body), leaving out the legs.

Females are clearly larger than males, a common pattern in frogs because larger females can produce more eggs. An adult weighs about as much as two or three sugar cubes.

Where do red-eyed tree frogs live?

Red-eyed tree frogs live in humid lowland and foothill forests from southern Mexico through Belize, Guatemala, Honduras, Nicaragua, Costa Rica and Panama to northwestern Colombia. They are most widespread on the Caribbean (Atlantic) side of Central America and also occur on the Pacific side in parts of Costa Rica and Panama. They are found from sea level up to about 1,250 m (4,100 ft).

The key requirement is still water for breeding: ponds, swamps, flooded ditches and slow backwaters with plants hanging over them. The frogs need high humidity and spend their lives in the trees and shrubs around these sites, often in the middle and upper layers of the forest. They also use secondary forest, forest edges and gardens if water and cover are nearby. For a fuller picture of the range and habitat, see where do red-eyed tree frogs live?.

What do red-eyed tree frogs eat?

Adult red-eyed tree frogs are insectivores and hunt at night. They eat crickets, katydids, grasshoppers, moths, flies, mosquitoes and other insects, along with spiders and other small invertebrates. Larger individuals occasionally eat smaller frogs.

They are mostly sit-and-wait hunters. A frog waits on a branch or leaf, watches for movement with its large eyes and then lunges, catching prey with its sticky tongue. Good night vision matters for this: the vertical pupils open wide in darkness and close to narrow slits in bright light.

The tadpoles have a different diet. In the water they feed on algae, plant material, tiny particles and plankton, and they also scavenge and sometimes eat other tadpoles.

Behavior: a nocturnal life in the leaves

Red-eyed tree frogs are strictly nocturnal. During the day an adult clings to the underside of a broad leaf, tucks its colorful legs and feet under its body, presses its belly flat and closes its eyes. In this pose it looks like a small green bump on the leaf and is hard for birds and other day-hunting predators to spot.

At night the frogs wake up, open their eyes and move through the vegetation to hunt and, in the breeding season, to call. They are agile climbers that often walk hand over hand along stems, gripping with their toe pads and long fingers, and they can also leap between branches. To learn how those pads work, read how do tree frogs stick to leaves?.

If a predator disturbs a resting frog, it may suddenly open its red eyes and flash its blue flanks and orange feet before jumping away. Biologists call this a startle display. It is the main explanation for the frog’s striking colors, discussed in why do red-eyed tree frogs have red eyes?.

Males are also known for an unusual form of communication. Besides calling, they shake the branch or leaf they sit on with rapid movements of their body, sending vibrations that rival males can feel. This branch shaking, called tremulation, is used in contests between males.

Reproduction and life cycle

Breeding takes place in the rainy season, roughly from May to November in much of the range, when ponds and puddles fill up. Males gather around the water at night and give short “chack” calls from the vegetation. Competition is intense, and males sometimes wrestle each other for a female.

A female chooses a male, who climbs onto her back and grips her in a mating embrace called amplexus. She then carries him down to the water, where she absorbs water through her skin, and back up to a leaf hanging over the pond. There she lays a clutch of usually about 40 eggs (from about 10 to more than 100) in a clear jelly, and the male fertilizes them as they emerge. A pair may lay several clutches in one night, returning to the water in between.

The eggs normally hatch after about 6 to 10 days. The tadpoles wriggle free of the jelly and drop from the leaf into the water below, which is why the eggs are laid over water. The most remarkable part of the story is early hatching. Research by Karen Warkentin and colleagues in Panama showed that embryos can hatch early, sometimes days ahead of schedule, when they feel the vibrations of an attacking snake or wasp, or when the clutch is threatened by flooding or drying. Hatching early lets them escape into the water, although very young tadpoles are more vulnerable to fish and other aquatic predators.

The tadpoles grow in the water for several weeks to a few months, depending on temperature and food, before turning into froglets and climbing out. The young frogs are brown at first and gain their green color and red eyes as they mature. You can follow the general process in how do tadpoles turn into frogs?.

How long do red-eyed tree frogs live?

Wild red-eyed tree frogs are thought to live about 5 years. Many never reach adulthood, because eggs and tadpoles are eaten in large numbers. In captivity, where there are no predators and food is regular, individuals have been reported to live more than 8 years.

Predators and threats

Red-eyed tree frogs are prey for many animals at every stage of life:

• Eggs: cat-eyed snakes (Leptodeira) and social wasps eat whole clutches, and fungi can kill eggs.
• Tadpoles: fish, freshwater shrimp, dragonfly larvae and water beetles.
• Adults: snakes, birds, frog-eating bats, large spiders and other predators.

Camouflage by day, the startle display and the ability to leap away are the frog’s main defenses. It does not rely on poison.

Conservation status

The IUCN Red List classifies the red-eyed tree frog as Least Concern. The species has a large range, lives in many protected areas and tolerates some disturbance, such as secondary forest and the edges of farmland.

That does not mean it is free of problems. Deforestation and drainage of breeding ponds remove habitat, and amphibian diseases such as chytrid fungus and ranaviruses affect frogs in the region. Collection for the international pet trade has also been a concern in some areas, and since 2010 the species has been listed in CITES Appendix II, which means international trade must be permitted and monitored.

Red-eyed tree frog myths and facts

• Myth: the bright colors mean it is poisonous. In fact the red-eyed tree frog is not poisonous like the poison dart frogs. Its colors are mostly hidden at rest and are used to startle, not to warn. More in are red-eyed tree frogs poisonous?.
• Myth: the frog is easy to see in the forest. Despite its famous photos, a resting frog with its eyes closed and legs tucked in is very well camouflaged against a green leaf.
• Fact: its eggs can “decide” when to hatch. Embryos respond to the vibrations of predators by hatching early, one of the best-studied examples of this behavior in any animal.

Red-eyed tree frogs and people

The red-eyed tree frog has become a symbol of tropical rainforests. Its image appears on posters, books and conservation campaigns, and it is one of the animals visitors most hope to see on night walks in Costa Rica and Panama. It is also well known to scientists, who study its early hatching, vibration signals and color variation at field stations such as La Selva in Costa Rica and Barro Colorado Island in Panama.

Watching these frogs in the wild is best done at night during the rainy season, near ponds in lowland forest, with a guide and a dim light. Looking without touching protects the frogs, whose thin skin is easily harmed by handling.