Darwin’s Frog
It is endemic to the temperate forests of the south-central region and Patagonia of Chile and Argentina
Conservation Efforts | Pumalín Douglas Tompkins National Park
Deep within the Valdivian rainforest, where mist and rain sustain a vibrant yet fragile ecosystem, Rewilding Chile has launched a new amphibian monitoring program in Pumalín Douglas Tompkins National Park. At its heart is one of the forest’s most mysterious and threatened inhabitants: Darwin’s frog, a tiny yet vital species.
Endemic to the temperate rainforests of Patagonia, Rhinoderma darwinii is much more than a small, discreet amphibian. Its highly permeable skin makes it extremely sensitive to environmental changes, turning it into a sentinel species that reveals the health of the ecosystem it inhabits.
From Concepción to Aysén in Chile, and in some bordering areas of Argentina, this tiny frog—only a few centimeters long—camouflages perfectly among the forest leaf litter, making it incredibly hard to find. Its name honors Charles Darwin, who first described it in 1834 during his voyage through South America. Fascinated by its unusual appearance and behavior, he mentioned it in The Voyage of the Beagle.
This research program, carried out in collaboration with CONAF, aims to better understand the status of Darwin’s frog populations and their role in maintaining ecosystem balance by studying their interactions, ecological functions, and threats. This knowledge will help develop concrete strategies for their conservation and long-term survival.
Among the researchers who helped launch this project was naturalist, photographer, and herpetologist Andrés “Andy” Charrier, who passed away in July 2025. Andy served as an advisor to the program, contributing his deep knowledge and leadership to the creation of the Darwin’s Frog and Accompanying Amphibians Program.
“Amphibians depend directly on water, humidity, and rainfall. They are the most threatened group among all terrestrial vertebrates. They have always been sentinels—true environmental thermometers—that tell us how healthy an ecosystem is,” explained Andy Charrier.
“Amphibians depend directly on water, humidity, and rainfall. They are the most threatened group among all terrestrial vertebrates. They have always been sentinels—true environmental thermometers—that tell us how healthy an ecosystem is,” explained Andy Charrier.
Species Overview
One of the smallest frog species in the world, Darwin’s frog is hard to spot in its natural habitat thanks to its remarkable camouflage that makes it look just like a fallen leaf.
It has a rounded body, a triangular head with a pointed snout, and a small nasal appendage. Females are slightly larger, measuring between 2.5 and 3.5 cm, while males rarely exceed 2.8 cm. Its legs are long and slender; the front ones lack webbing, and only the first three toes of the back legs have a thin membrane.
Its skin is slightly granular with lateral folds and varies in color from bright green to earthy browns and reddish tones.
Life cycle and reproduction
Darwin’s frog has one of the most extraordinary reproductive strategies in the animal kingdom: male incubation. This rare behavior, called neomely, is otherwise known only in a few fish species such as seahorses.
During spring and summer, males call to females with soft, whistling sounds during the day. After a brief mating embrace known as amplexus, the female lays her eggs in a small cavity among moss, where the male fertilizes them. The female then leaves, and the male stays to guard the eggs.
After two or three weeks, the movement of the developing tadpoles triggers the male to swallow the eggs, storing them in his vocal sac—a modified part of his throat. Inside, the tadpoles complete their metamorphosis over six to eight weeks, nourished and oxygenated through the walls of the sac.
When the young frogs are fully developed, the male gently releases them into the damp forest floor. They emerge already as miniature adults, with limbs fully formed and only a small tail remnant, which is absorbed within days. After about two years, they reach reproductive maturity and the cycle begins again.
Al momento de la liberación ya tienen su forma adulta completada, con miembros delanteros y posteriores bien formadas, sólo presentan un pequeño apéndice o vestigio de cola que es reabsorbida durante los primeros días de vida libre.. A partir de ese momento, inician su vida completamente independientes y tras aproximadamente dos años, alcanzan la madurez sexual o reproductiva.
Darwin’s frog and accompanying amphibians
Distribution and Habitat
Darwin’s frog (Rhinoderma darwinii) is endemic to the temperate rainforests of southern Chile and Argentina, thriving in native forests of araucarias, coigües, canelos, alerces, and cypresses—from sea level up to about 1,800 meters. It favors old-growth forests with stable temperature and humidity.
In Argentina, populations are found mainly in the border regions, particularly in Nahuel Huapi and Lanín National Parks, across Río Negro and Neuquén provinces. In Chile, there are two known Darwin’s frog species: the northern Darwin’s frog (R. rufum) and the southern Darwin’s frog (R. darwinii).
The northern species once lived in the native coastal forests between Zapallar and Concepción but has not been seen since 1981, and may be Chile’s first extinct amphibian. Its historical range is now heavily altered due to population growth and habitat loss caused by agricultural expansion.
This alarming situation highlights the urgent need for research and conservation efforts focused on Chile’s native amphibians.
Behavior and Diet
Like most amphibians, Darwin’s frog is carnivorous, feeding mainly on small insects and invertebrates such as crickets, spiders, and worms. It is a diurnal species, spending its days among dense vegetation, mosses, and ferns while searching for food.
Adults show strong site fidelity—they tend to stay within the same small home range, moving on average only six meters per year. Their home territory is estimated at around two square meters.
One of the most fascinating traits of Darwin’s frog is its call—a high-pitched whistle reminiscent of a bird’s song, often compared to the chirp of a newborn duckling or the call of the Fío-Fío (Elaenia albiceps).
Threats
Amphibians worldwide face multiple threats that endanger their long-term survival. Darwin’s frog and its relatives are particularly vulnerable to a fungal disease known as chytridiomycosis, caused by Batrachochytrium dendrobatidis, which infects their skin and disrupts vital physiological processes.
Habitat loss from monoculture plantations (pine, eucalyptus, avocado, vineyards) further worsens their condition, as these species depend on both water and soil, and their permeable skin makes them highly sensitive to environmental changes.
New threats such as wildfires, prolonged droughts, and shifting rainfall patterns also affect their breeding success.
A 2022 study by the Center for Applied Ecology and Sustainability and the Institute of Ecology and Biodiversity found that 12 of Chile’s 60 native amphibians could go extinct due to climate change. By 2050, all species analyzed are expected to experience severe distribution changes—and some, including Darwin’s frog, could disappear forever.
Conservation Status
Today, Rhinoderma darwinii is listed as Endangered under Chile’s Species Classification Regulations and the IUCN Red List, while Rhinoderma rufum is classified as Critically Endangered in both systems.
Globally, amphibians are in crisis: their extinction rate is 211 times higher than historical levels, making them the most threatened group of terrestrial vertebrates. The chytrid fungus alone has caused the decline of over 500 amphibian species and the extinction of at least 90.
The main drivers of this crisis are habitat destruction, emerging wildlife diseases, climate change, invasive species, and pollution.
In this challenging context, Rewilding Chile seeks to deepen understanding of the ecological dynamics and threats affecting Patagonia’s ecosystems—through long-term monitoring and conservation programs designed to ensure the survival of Darwin’s frog and other southern amphibians.
