Red-Eyed Tree Frog — facts, diet, habitat & conservation

The red-eyed tree frog is one of the most photographed animals in the world — the poster amphibian for tropical rainforests. What the photos do not show is that its entire survival strategy is a performance. It has no poison. It has a bluff.

Overview

Red-eyed tree frogs live in the humid lowland rainforests of Central America, always near a pond or slow stream. They are nocturnal and arboreal, spending the day asleep on the underside of a leaf and the night climbing through the vegetation hunting insects. The species is common enough that it has become a symbol of rainforest conservation, its bright face used on posters and logos worldwide.

Physical characteristics

The body is vivid leaf-green, sometimes with white spots or fine bluish lines. The flanks are barred blue and cream, the upper legs are blue, the feet are orange, and the eyes are a startling scarlet with narrow vertical pupils. The toes end in large adhesive pads that grip smooth wet leaves.

None of these bright colours are visible when the frog is at rest. It tucks its legs against its body, covering the blue and orange, closes its red eyes behind a marbled semi-transparent lower lid that still lets it sense light and movement, and becomes a plain green lump indistinguishable from a leaf.

The startle defence

When a predator — a snake, a bird, a bat — discovers a sleeping frog despite the camouflage, the frog does not run immediately. It flashes: eyes snapping open to reveal two large red discs, legs kicking out to expose the blue and orange, the whole animal seeming to change instantly from a leaf into a bright, alien creature.

The effect on the predator is a momentary hesitation, and researchers think it also leaves a misleading after-image — the hunter’s eye holds a “ghost” of a red-eyed, blue-flanked frog for a fraction of a second after the real frog has already leapt away into the dark. That fraction of a second is often enough.

Reproduction and hatching

In the rainy season, males call from vegetation over water and, when a female arrives, ride on her back while she descends to lay a clutch of 30–50 eggs on the underside of a leaf overhanging a pond. Over several nights she may lay multiple clutches, carrying water up from the pond in her bladder to keep them from drying out.

The embryos develop in the jelly for about a week — but they can hatch on demand. If the clutch is attacked by an egg-eating snake or a wasp, the vibrations trigger embryos as young as four days old to hatch prematurely, thrashing free of the jelly and dropping into the water below, trading the risk of being eaten in the egg for the risk of being an undersized tadpole.

Threats and conservation

The red-eyed tree frog is Least Concern but declining. Its rainforest habitat is being cleared for cattle pasture, plantations, and development across Central America. As a moisture-dependent amphibian with permeable skin it is also exposed to agricultural chemicals, and to the chytrid fungus that has wiped out other frog species in the same forests. For now it remains one of the region’s more resilient amphibians, partly because it tolerates disturbed, secondary forest better than many of its neighbours.

Red-Eyed Tree Frog: common questions

Is the red-eyed tree frog poisonous?

No. Unlike the poison dart frogs it shares the rainforest with, the red-eyed tree frog has only mild skin secretions and relies entirely on hiding and startling predators to survive.

Why does it have red eyes?

For a trick called startle or flash colouration. A sleeping frog is folded up and pure green, invisible against a leaf. If a predator finds it anyway, the frog suddenly opens its huge red eyes and flashes the blue-and-yellow flanks and orange feet it had hidden. The predator freezes for a split second at the burst of colour — long enough for the frog to leap away, leaving an after-image of a red-eyed creature that has vanished.

Can frog eggs really hatch early?

Yes, and the red-eyed tree frog is the classic example. Its embryos develop inside jelly clutches stuck to leaves over a pond. If they sense the vibrations of a snake or wasp attacking the clutch, embryos as young as four days — a day or more before they would normally hatch — can burst out early and drop into the water to escape.

Are red-eyed tree frogs endangered?

The species is listed as Least Concern and is still widespread, but its population is declining as Central American rainforest is cleared, and like all amphibians it is vulnerable to the chytrid fungus and to pollution.