Animal
Amazon milk frog
The Amazon milk frog is a big tree frog. It lives high up in rainforest trees and has golden eyes. It lays its eggs in little pools of water inside trees.
The Amazon milk frog is a large tree frog that lives high in the treetops of the rainforest in northeastern South America. It is active at night, has big golden eyes, and lays its eggs in pools of rainwater trapped in holes in trees, where its tadpoles grow up.
Trachycephalus resinifictrix is a large, nocturnal treefrog of the canopy of primary rainforest in the eastern Amazon basin and the Guianas. It breeds only in water-filled tree holes, often many meters above the ground, and gets its common name from a milky secretion it releases when threatened. Since a 2013 taxonomic split it is known from a smaller range than before.
Photo: Crusier, CC BY 3.0, via Wikimedia Commons
Meet the Amazon milk frog
The Amazon milk frog is a big tree frog.
It is brown and pale gray, with tiny white spots. It has golden eyes. It lives high up in rainforest trees and comes out at night.
The Amazon milk frog is one of the larger tree frogs: a grown-up female can be about as long as an adult's palm. Adults have bands of brown and pale gray, bumpy skin dotted with white spots, and big golden eyes, which is why it is also called the Mission golden-eyed tree frog.
It got its name 'milk frog' because it can give off a milky white liquid when it feels threatened. It lives high in the rainforest treetops and is busy at night.
Trachycephalus resinifictrix is a large amphibian (class Amphibia) of the treefrog family Hylidae: Mignet (2015) gives adult snout-vent lengths of 86 to 100 millimeters for females and 65 to 77 millimeters for males. Diagnostic features include a short, blunt snout, a large dorsal patch, a granular belly, and a back and sides covered in small pustules.
Zoo accounts, such as the Buffalo Zoo's, explain the common name: the frog secretes a milky white poison when threatened. The IUCN lists English names including Mission Golden-eyed Treefrog and Amazon Milk Frog. The photographed milk frog is a captive at Warsaw Zoo in Poland.
Quick facts
- Group
- Amphibian
- Length
- 0.07 to 0.1 m
High in the rainforest
Milk frogs live in the Amazon rainforest in South America.
They live very high up in the treetops. They may hardly ever come down to the ground.
Amazon milk frogs live in the rainforest of northeastern South America: the eastern Amazon in Brazil and the Guianas (Guyana, Suriname and French Guiana).
They live in the canopy, the leafy roof of the forest high above the ground, and they may seldom, if ever, come down. Scientists rarely find them, probably because they stay so high up in the trees.
The IUCN's 2023 assessment restricts the species to the eastern Amazon basin in Brazil (Amazonas and Pará states; possibly Amapá and Roraima) and north into Guyana, Suriname and French Guiana, at 0 to 450 meters. Records from the central and southern Amazon in Brazil, Bolivia, Peru and Ecuador, and probably Colombia, were reassigned to Trachycephalus cunauaru after a 2013 study, and Venezuelan records remain uncertain.
It inhabits the canopy of tropical primary rainforest and may seldom, if ever, descend to the ground. The IUCN suggests that its arboreal habits are probably why it is rarely recorded; its population trend is unknown.
Continent
Its habitat
Where can you find this animal?
- Lives here naturally · Countries and seas named by a scientific source
- Sightings recorded · Records of wild sightings (GBIF)
Lives here naturally · Countries and seas named by a scientific source
Canopy of lowland primary rainforest in the eastern Amazon basin of Brazil (Amazonas and Pará) and the Guianas, including French Guiana (not shaded separately). Records from the western and southern Amazon now belong to a related milk frog; Venezuela is uncertain and not shaded.
Places: Brazil, Guyana and Suriname.
Source: iucn-red-list · checked October 2026
Sightings recorded · Records of wild sightings (GBIF)
Counts of GBIF records of wild observations (human and machine) and preserved specimens. Records include introduced populations, vagrants, escaped or released animals and misidentifications, so a country with records is not necessarily part of the native range.
Wild sightings have been recorded in Brazil, Colombia, Peru, Venezuela, Suriname, Ecuador, Guyana and Bolivia.
Source: gbif · checked October 2026
Range maps show where scientists say an animal lives, often country by country. An animal may live in only part of a country shown, and sightings records can include animals that wandered far from home.
Night-time insect hunter
Milk frogs eat bugs.
At night they hunt insects in the trees. Baby milk frogs, called tadpoles, eat tiny bits of plants and algae in the water.
Adult milk frogs are insectivores, which means they eat insects. They hunt at night among the branches high in the trees.
Their tadpoles have a very different menu. Living in small pools inside tree holes, they eat algae and bits of rotting plants, and sometimes they eat eggs laid by other milk frogs in the same pool.
Adults are nocturnal insectivores of the canopy (Buffalo Zoo; Mignet 2015). Tadpoles develop in water-filled tree holes, a small, closed habitat; Mignet (2015) reports that in the wild they feed on algae and plant detritus and sometimes on eggs of their own species, an opportunistic form of egg-eating called oophagy.
Did you know?
One milk frog can lay hundreds of eggs.
A single milk frog clutch in the wild can have more than a thousand eggs.
Wild clutches of 106 to 1,540 eggs have been recorded (Schiesari and colleagues, cited by Mignet 2015).
Golden eyes and bumpy skin
Milk frogs have big golden eyes.
Their skin is bumpy, with tiny white dots. Their legs have stripes. Their toes end in round pads.
A milk frog has big eyes ringed with gold. Its skin is covered in small bumps and white dots, and its legs are banded brown and pale gray, like stripes.
When it feels threatened, the skin can give off a milky white liquid, which is how the frog got its name. Young milk frogs look different from adults: they start out dark brown or gray and get their adult pattern as they grow.
Diagnostic characters given by Mignet (2015) include a short, blunt snout, only a low fold of skin above the eardrum, a large dorsal patch, a granular belly, and small pustules covering the back and sides. Limbs carry dark crossbars, and in young frogs the finger tips are blue-green.
Color changes with age: newly metamorphosed froglets are dark brown to dark gray with white-speckled limbs, and the adult pattern develops over the first year. The milky secretion released when the frog is threatened is described by the Buffalo Zoo as poisonous.
A nursery in a tree hole
Milk frogs lay their eggs in a pool of water inside a tree.
The eggs hatch into tadpoles. The tadpoles grow legs and turn into little frogs.
In the rainy season, male milk frogs call loudly from holes in tree trunks that are filled with rainwater. A female lays her eggs in the water, and there can be hundreds of them in one clutch.
The eggs hatch into tadpoles that swim in the little pool. Over several weeks they grow legs and turn into tiny froglets about 1 to 1.5 centimeters long.
Reproduction takes place only in water-filled tree holes (phytotelmata). Tree holes used by the species measured 15 to 190 centimeters deep, held 2.8 to 90 liters of water and lay 2 to 32 meters above the ground; males call from them, mostly during the rainy season from about August or September to April or May (Schiesari and colleagues, cited by Mignet 2015). Clutches in nature contained 106 to 1,540 eggs.
In a zoo breeding program, tadpoles metamorphosed after about 6 to 10 weeks, some taking 14 to 16 weeks, and new froglets measured 1 to 1.5 centimeters. Growth then slows: Mignet's young frogs looked like adults at one year old but measured only about 5 to 5.5 centimeters, and he considers females unlikely to breed at that age.
Loud calls in the night
Milk frogs sleep in the day and wake up at night.
The males call very loudly from holes in trees. Their calls help the females find them.
Milk frogs are nocturnal, which means they are active at night and rest during the day. They are known for their loud calls.
A male calls from a water-filled hole in a tree to attract a female, and that same hole is where the eggs will be laid.
The species is nocturnal and arboreal and, as the IUCN notes, is characterized by loud vocalizations. Males call from water-filled tree holes to attract females; the hole is both a calling site and the future nursery.
Mignet (2015) notes that although the species is commonly bred in zoos, very little about that breeding had been published, and wild frogs are rarely recorded.
Did you know?
Milk frog babies grow up in a pool inside a tree.
Milk frog tadpoles grow up in rainwater trapped in tree holes, which can be more than 30 meters above the ground.
Breeding tree holes were found 2 to 32 meters above the ground, holding 2.8 to 90 liters of water (Schiesari and colleagues, cited by Mignet 2015).
Protecting the rainforest canopy
There are many milk frogs, and they are not in danger.
They need tall rainforest trees with holes full of rainwater. Keeping the rainforest safe keeps them safe.
The IUCN lists the Amazon milk frog as Least Concern, because it lives across a large area and there are probably many of them. It lives in several protected areas.
Still, cutting down the rainforest can harm the frogs in some places. They need old, tall trees with water-filled holes for their tadpoles. Many zoos also breed milk frogs.
The IUCN Amphibian Specialist Group assessed the species as Least Concern in 2021 (published 2023), given its wide distribution and presumed large population; the population trend is unknown. Local populations are likely affected by forest conversion, clear-cutting, selective logging and human settlement, and the species occurs in several protected areas.
It is also found in the pet trade and in zoos. Mignet (2015) notes that it is commonly bred in zoos and is easy to raise, and presents its breeding as a model for programs for endangered frogs with similar needs. Research is still needed on whether frogs in parts of Venezuela, Peru and Colombia belong to this species.
IUCN Red List
How is the amazon milk frog doing in the wild?
- Least Concern (this animal)
- Near Threatened
- Vulnerable
- Endangered
- Critically Endangered
- Extinct in the Wild
- Extinct
Least Concern
Not at risk of disappearing from the wild right now.
Amazing facts
-
Milk frog babies grow up in a pool inside a tree.
Milk frog tadpoles grow up in rainwater trapped in tree holes, which can be more than 30 meters above the ground.
Breeding tree holes were found 2 to 32 meters above the ground, holding 2.8 to 90 liters of water (Schiesari and colleagues, cited by Mignet 2015).
-
One milk frog can lay hundreds of eggs.
A single milk frog clutch in the wild can have more than a thousand eggs.
Wild clutches of 106 to 1,540 eggs have been recorded (Schiesari and colleagues, cited by Mignet 2015).
-
The milk frog is named for a white, milky liquid on its skin.
When it feels threatened, a milk frog can give off a milky white liquid from its skin, and that is how it got its name.
The common name comes from a milky skin secretion released when the frog is threatened; the Buffalo Zoo describes it as poisonous.
-
Baby milk frogs change color as they grow.
New froglets are dark brown or gray with white-speckled legs, and they get their adult bands over their first year.
Froglets are dark brown to dark gray at metamorphosis; the adult gray-brown pattern with crossbarred limbs develops over about a year (Mignet 2015).
Words to know
- canopy
- the high, leafy roof of a forest, made by the tops of the trees
- nocturnal
- active at night and resting during the day
- tadpole
- a young frog that lives in water, breathes with gills and has a tail
- metamorphosis
- a big change in body shape as an animal grows, like a tadpole turning into a frog
- insectivore
- an animal that eats mainly insects
- arboreal
- living in trees
Discovery challenge
-
Where do milk frogs lay their eggs?
Where do Amazon milk frogs lay their eggs?
What kind of breeding site does Trachycephalus resinifictrix use?
- In rainwater inside tree holes
- In the ocean
- In sand on a beach
Show the answer
In rainwater inside tree holes
They lay their eggs in little pools of rainwater inside trees.
They lay eggs in tree holes filled with rainwater, high above the ground.
Exclusively water-filled tree holes (phytotelmata), 2 to 32 meters above the ground.
-
When are milk frogs awake?
When are Amazon milk frogs most active?
Which word describes the milk frog's daily activity?
- At night
- Only at noon
- Only in winter
Show the answer
At night
They wake up at night.
They are nocturnal: active at night and resting in the day.
Nocturnal and arboreal, calling and foraging at night in the canopy.
-
How did the milk frog get its name?
Why is it called a milk frog?
What is the origin of the name 'milk frog'?
- It drinks milk
- Its skin can give off a milky liquid
- It is white all over
Show the answer
Its skin can give off a milky liquid
Its skin can make a milky white liquid.
When threatened, its skin gives off a milky white liquid.
A milky skin secretion released when the frog is threatened.
-
Where do milk frogs live?
In which part of the rainforest do Amazon milk frogs live?
Which forest layer does the species inhabit?
- Under the ground
- High in the treetops
- In rivers
Show the answer
High in the treetops
They live high up in the treetops.
They live in the canopy, the leafy top of the rainforest, and may hardly ever come down.
The canopy of tropical primary rainforest; it may seldom, if ever, descend to the ground.
Places where you might see it
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For parents & teachers
What children will learn
- Describe how the Amazon milk frog lives in the rainforest canopy and why it is rarely seen.
- Explain the milk frog's life cycle, including tadpoles growing in water-filled tree holes.
- Understand that scientists sometimes discover that one 'species' is really two, changing where we think it lives.
Recommended ages: 3 to 17 · About 10 minutes
Talk about it
- Why might a tree hole be a safer place for tadpoles than a big pond? What problems might a tiny pool cause?
- Why do you think frogs that live high in the canopy are hard for scientists to study?
- How can zoos help frogs in the wild?
Try at home or in class
- Leave a cup outside in the rain and measure how much water collects: imagine a whole family of tadpoles living in a tree-hole pool.
- Draw the life cycle of a milk frog in four boxes: eggs, tadpole, tadpole with legs, froglet.
Key vocabulary: canopy, nocturnal, tadpole, metamorphosis, insectivore, arboreal
Where these facts come from
- The IUCN Red List of Threatened Species , International Union for Conservation of Nature (IUCN terms of use (no redistribution of Red List data or range maps))
- GBIF Backbone Taxonomy and GBIF Occurrence Search , Global Biodiversity Information Facility (CC0 1.0 (backbone); occurrence counts are facts derived from records under CC0, CC BY and CC BY-NC)
- Trachycephalus resinifictrix (Mission Golden-eyed Treefrog), 2023 global assessment , IUCN Red List of Threatened Species (IUCN SSC Amphibian Specialist Group)
- Biology and Captive Breeding of the Amazonian Milk Frog, Trachycephalus resinifictrix (Goeldi 1907), Reptiles & Amphibians 22(2): 68-75 (Mignet 2015) , International Reptile Conservation Foundation, via University of Kansas Libraries
- Amazon milk frog , Buffalo Zoo
- Wikidata , Wikimedia Foundation (CC0 1.0)
- Wikimedia Commons , Wikimedia Foundation (Per file: Public domain, CC0, CC BY or CC BY-SA only (credited on each page))
Checked, not yet human-reviewed. Last updated October 27, 2026. Spotted a mistake? Tell us.