Darwin's frog dads raise their young inside a vocal sac

In the cool forests of southern Chile, a frog about an inch long can spend nearly two months with his children inside his throat. The Animal Diversity Web (ADW), a University of Michigan database, says that when the young are ready, the father releases them as miniature frogs. EDGE of Existence, a conservation program, says they hop out of his mouth about 50 days after he took them in. As parental leave goes, that is hard to beat.

This is Darwin’s frog, Rhinoderma darwinii, and the job belongs to the father. The sac he uses is a vocal sac, the stretchy pouch of skin under a male frog’s throat that most frogs inflate to call. In this species it doubles as a nursery. The frog is Endangered, and a fungal disease that reached its largest known stronghold in 2023 has turned part of its story into a rescue mission.

This article follows the nursery step by step, shows where the sources disagree, and says plainly what none of them confirm.

Meet Darwin’s frog

Darwin’s frog lives in temperate forests and rainforests of Chile and Argentina. EDGE says its coloring hides it against the leaves of Chilean bamboo and monkey puzzle trees on the forest floor.

The two size sources do not match, so the table shows both. The pointed nose is the feature to look for, because it helps tell this frog from a plain small brown one.

The father’s nursery, step by step

The sources describe the same sequence with small differences in wording. Here is the sequence as they report it.

Two details deserve a flag. The ADW and Mongabay say the male takes in the tadpoles after they hatch, while EDGE and Discover Wildlife describe him reacting to twitching embryos. Grzimek’s Animal Life Encyclopedia sides with the embryo version: it says the male waits about 20 days, until the eggs are nearly ready to hatch, then takes the eggs into his mouth, and they soon hatch in the vocal sac. Three of the five sources point to late-stage eggs, so that is the reading we favor, though it is not settled. The second flag is the duration: about 6 weeks, about 50 days, 50 to 70 days, or just “days.” That is why we say six to ten weeks.

One more point clears up a common worry. The ADW describes the young developing in the sac and emerging as complete, living froglets. The pickup is a transfer, not a meal.

The cousin that did it differently

There are two Darwin’s frogs. The northern species, Rhinoderma rufum, has a different method. Mongabay, summarizing a 2013 study, reports that the northern male moves the tadpoles to fresh water and releases them there, while the southern male keeps them in his sac until they are froglets.

The northern species may be gone. The 2013 study in PLoS ONE, by Claudio Soto-Azat and colleagues, says it has not been recorded since 1980. The team visited every known site and found no frogs. They used a model to estimate extinction around 1982, with a 95% confidence interval running from 1980 to 2000, and they recommended listing it as Critically Endangered (Possibly Extinct). The authors also say hope remains that it survives somewhere. An estimate is not a death certificate. Discover Wildlife says it has been presumed extinct since 1981, a small difference from the 1980 last record.

Why fatherhood was not enough

Parenting does not help much when the forest disappears. Soto-Azat and colleagues found the southern species at 36 sites in 26 areas, in small and fragmented populations. They name the replacement of native forest by pine and eucalyptus plantations, farms and towns as major pressures. EDGE says pine planting dried the forest floor. Mongabay, reporting on the same study, says natural forest in the central-south coastal range fell 67% from 1975 to 2000.

Habitat loss does not tell the whole story. The 2013 authors say it does not fully explain the disappearances, because frogs also vanished from protected areas. They point to volcanic eruptions that coincided with local losses, illegal pet-trade collection, and the risks of small populations. They suggest chytrid fungus and climate change might contribute, but at that time the fungus’s impact on wild Darwin’s frogs had not been investigated.

That has changed. The IUCN Amphibian Specialist Group website says chytrid, the fungus behind the disease chytridiomycosis, reached Tantauco Park in southern Chile in 2023. The park had held the largest known populations and was free of the fungus until then. More than 1,300 frogs died in the first year. In October 2024, 53 frogs flew about 13,000 kilometers (roughly 8,000 miles) to ZSL London Zoo, a trip that involved 51 people from 9 institutions, and all survived. The plan is a breeding network, with offspring eventually returning to Chile. For the disease itself, see the Panamanian golden frog.

What the sources do not tell us

• How long the father guards the eggs, for certain. EDGE says he waits until the young start to wriggle. Grzimek’s gives about 20 days, and the other pages we opened give no number.
• How many eggs there are. None of the pages we could open give a count.
• What the young feed on inside the sac. None of the pages we opened explain it.
• A single size. The two sources differ, so we say roughly an inch.
• Whether the northern species survives. The 2013 authors cannot rule it out.

Common mistakes and myths about Darwin’s frog

Mix-up: the father eats his young. He takes them into his mouth and holds them in the vocal sac while they grow, then they come out as froglets.

Mix-up: vocal sacs are only for singing. Most frogs use them to call. For a tour of that job, see the spring peeper. Here the same structure is a nursery.

Myth: both Darwin’s frogs raise young the same way. Per Mongabay, the northern male released tadpoles into water.

Mix-up: frog parenting always looks like this. Frogs parent in many ways. A 2019 field study of the Goliath frog found cleared nests, and a camera trap showed a large frog sitting by one through the night. The authors say it is unclear which sex builds or guards the nests.

Myth: habitat loss alone explains the decline. The 2013 authors say it does not.

Conservation status

Darwin’s frog is listed as Endangered on the IUCN Red List of Threatened Species. That is the category as distributed by GBIF, the Global Biodiversity Information Facility, and we checked it on November 9, 2026. Endangered means the species is judged to face a very high risk of extinction in the wild.

Older pages can lag. The ADW lists the species as Vulnerable, and Mongabay reports that it was Vulnerable in 2013, when the study’s authors proposed upgrading it. The Amphibian Specialist Group website and Discover Wildlife both say Endangered. The pressures our sources name are forest loss, climate change and chytridiomycosis. The sources give no confirmed overall population trend, though one park lost more than 1,300 frogs in a year. For a species like this, the date on a category matters.

Categories are reviewed and can change, and the copy GBIF distributes can trail the IUCN website by some months. GBIF’s copy does not give the year of the IUCN assessment, so we do not state one.