Darwin’s Frog

Quick Take

• Darwin's frog fathers have a parenting trick so bizarre it sounds impossible, and it is nothing like what any other frog does. Discover vocal sac parenting →
• This frog's camouflage goes beyond color. Each individual has a unique body pattern that works like a fingerprint. See their unique markings →
• One of Darwin's frog's two species may already be gone forever, wiped out by something far deadlier than any predator. Learn about the chytrid threat →
• A frog the size of a sewing thimble can hit speeds that would surprise you, and it relies on a very specific body feature to do so. Check their surprising speed →

Darwin’s frog is native to streams and forests of Chile and Argentina. This tiny frog species gets its name from explorer Charles Darwin. He discovered the frog during his famous “Voyage of the Beagle” from December 1831 to October 1836. Darwin’s frog is able to camouflage itself on the forest floor, thanks to its evolution to look like a dried-up leaf.

5 Darwin’s Frog Facts

• Male Darwin’s frogs carry hatchling tadpoles in their vocal sac for about 50 to 70 days.
• Darwin’s Frogs are carnivores, eating small insects, snails, worms, and spiders.
• Both humans and fungus are to blame for the frogs’ decline toward extinction.
• These tiny frogs only grow up to 1.4 inches in length.
• Despite being small, Darwin’s frogs travel at speeds of up to five miles per hour.

Classification and Scientific Name

Commonly called Darwin’s frogs, these tiny amphibians of the class Amphibia bear the scientific name of Rhinoderma darwinii. They belong to the family Rhinodermatidae.

Two species of Darwin’s Frogs exist. One originates in northern Chile (Rhinoderma rufum), while the other lives in southern Chile and Argentina (Rhinoderma darwinii). Sadly, scientists believe the northern Darwin’s frog is extinct due to a deadly fungus outbreak. But hope remains that these northern species still exist somewhere in the forests of northern Chile.

In their scientific name, “rhinoderma” means rhinoceros-nosed. But they get their common name from the explorer who discovered and documented their existence, Charles R. Darwin.

Appearance and Behavior

Darwin’s frog’s upper body skin is brown or green in color with large blotches. Its bottom side is usually black or white. Its skin features many warts as well.

The tiny frog relies on its coloration and skin texture to camouflage itself on the forest floor and in streams, looking like a dried leaf. Each individual frog’s body print and colors work much like a fingerprint for humans. No two frogs have the exact same patterned appearance.

The frog’s body is rounded, but its head is shaped like a triangle with a pointed snout. Its thin legs work very well for hopping on the forest floor at speeds of up to five miles per hour. Only its hind feet have webbing between toes, ideal for swimming. This lets the front feet better grip the ground.

This little frog is similar in size to a sewing thimble. It averages from 0.9 to 1.2 inches in length.

Darwin’s Frog is a diurnal creature, meaning it sleeps at night and is mostly active during the daytime. When threatened by predators, the frog plays dead. It lies very still on the forest floor or floating in a stream. Its coloration and skin patterns make it look like a dead leaf, blending it in perfectly with forest debris.

Habitat

Darwin’s Frogs live in the glades and forests of Chile and Argentina. The frogs prefer living in forests, bogs, and along the edge of slow-moving streams or swamps. But they live at altitudes of up to 3,600 feet above mean sea level. Overall, their habitat includes grasslands, the woody debris of forest floors, mossy areas, young trees, young bushes, and elsewhere in native forests.

Darwin’s Frogs are best suited for places with short vegetation, which keeps the soil moist and at a cooler temperature. Since their coloration matches the habitats in which they live, they also find better places to hide from predators.

During the day and when sleeping, Darwin’s Frogs take shelter under logs or moss. They also enjoy basking in sunlight when no predators are near.

Diet

Like many of its amphibian and frog cousins, Darwin’s Frog is a meat-eater. To capture its prey, the carnivorous frog simply sits quietly and waits for passing insects, spiders, snails, and worms. When prey comes near, the frog ambushes it quickly and silently with its long, sticky tongue.

Predators and Threats

The biggest threats to Darwin’s Frogs are the fungus chytrid, which causes an infectious disease called chytridiomycosis. This fungal infection is capable of killing more frogs, more quickly than its natural predators or humans. Scientists do not know the origin of the fungus responsible for this fungal infection. But it is believed to have wiped out the entire population of the northern Darwin’s Frog species of northern Chile. This means only the southern population of Darwin’s frogs remains in southern Chile and Argentina.

Southern Darwin’s Frogs also face the ongoing threats of animal predators. These include rodents, snakes, and birds.

When a predator is near, the Darwin’s Frog uses its coloring to help it hide from the animal. By lying very still on the forest floor, the frog blends in with its surroundings. The predators only see what looks like another dead leaf on the ground. The frogs also drop or jump into a stream and float like a leaf down the river.

Humans threaten the Darwin’s Frog habitat through urbanization. Deforestation and encroaching cities take habitat from the frogs for human use. Other threats are the result of climate change: changing temperatures and increased UV exposure can kill the frogs.

The northern Darwin’s frog is believed to be extinct. Its southern cousin in southern Chile and Argentina is vulnerable to extinction. Their risk of extinction is primarily due to human deforestation, climate change, and fungal infection threats.

Reproduction, Babies and Lifespan

To reproduce, Darwin’s Frog males call out loudly during the night and throughout each day for females. This call is a quick pattern of “piiip” sounds. When a male finds a female to mate with, he leads her to shelter for breeding. This shelter is usually a mossy log or other partial covering.

The Darwin’s Frog is very unusual in how it takes care of its young. Each mating season ideally results in up to 40 clear eggs in a clutch. The female deposits the clutch of eggs into leafy debris on the forest floor. The male fertilizes the eggs, then stays nearby because his job is not finished. He waits for about three weeks near the clutch until the larvae are able to squirm within their eggs. He then scoops all of the eggs into his throat’s vocal sac. There, they spend about three days before hatching into tadpoles.

The tadpoles remain in the male’s vocal sac for another 50 to 70 days. During this time, the father frog provides nourishment from fluids within the sac. The tadpoles also gain nourishment from the yolk in the eggs.

At the end of their 50 to 70 days in the vocal sac, the tiny froglets move into their father’s mouth. The male frog then appears to spit the little frogs out. This process usually takes place at a stream.

Darwin’s Frogs can live 10 to 15 years in the wild.

Population

The International Union for Conservation of Nature (IUCN) lists Darwin’s Frogs (Rhinoderma darwinii) on their Red List of Threatened Species as endangered because the population is decreasing.

Listed conservation threats include:

• Urban development
• Agriculture and deforestation
• Fire and fire management
• Invasive diseases
• Pollution
• Volcanoes
• Droughts