Darwin’s frog is one of only two species of frog known to raise its young within the male’s vocal sac rather than in a body of water.
These amphibians have two distinct colorations. Some are green, others are brown and the rest are a combination of these colors. On the underside is a pattern of black and white which is thought to be behind their nickname of ‘cowboy frog.’
Protruding from the triangular head is a fleshy proboscis.
These animals are declining in the wild through a range of threats. One of the major ones is chytrid fungus.
Learn more about these amazing amphibians by reading on below.
Darwin’s frog is most noticeable due to the fleshy proboscis protruding from the triangle shaped head.
Their body is covered by warty skin colored brown or green with a combination of both also possible. The underside of their body is a pattern of black or white. Small yellow and orange spots may also be present on the underside. This coloration helps to provide camouflage in their environment.
The eye features a horizontal pupil.
They have thin legs which help them to hop around their environment. Only the back feet are partially webbed as they are primarily adapted for life on land.
Adults measure up to 3cm (1.25in) long with a weight of 2 to 4.8g (0.07 to 0.17oz). Females tend to be slightly larger than the males.
Darwin’s frog is a carnivore. They feed on invertebrates such as insects, worms and snails.
They are an ambush predator. These animals wait for prey to approach them and when it does they will stick out their long, sticky tongue to capture the prey.
South America is the native home of the Darwin’s frog. Here they are found in Argentina and Chile.
They make their home in temperate forests where they spend much of their time among leaf litter.
Some populations may be found near human habitations.
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Breeding can occur year round with a peak from November to March. Males will attract the female using a bell-like call.
The female deposits up to 40 large eggs in each clutch on to moist soil. After the eggs are laid the male performs much of the parental care. This begins with him defending the eggs.
These frogs have a unique breeding method. Instead of developing in the water the hatching eggs are gathered in the male’s mouth where the tadpoles will develop in his vocal sac.
During this developmental stage while the tadpoles are in the vocal sac they live solely off their own egg yolk.
When they finish their development they metamorphose and emerge from the father’s mouth. It takes around six weeks to reach metamorphosis.
These frogs are active during the day. When resting they shelter under logs or moss.
Outside of the breeding season Darwin’s frog is considered to be a solitary species.
Predators and Threats
When threatened the Darwin’s frog will freeze as if they are dead. They appear like a leaf which may also provide camouflage.
The biggest threat to Darwin’s frog is chytrid fungus which has emerged in North and South America along with Europe and Australia. It affects the skin of amphibians by stopping them absorbing water or nutrients.
Further threats are presented by forestry and drought. Fires may also present a threat. In parts of their range volcano eruptions may threaten local subpopulations.
Currently the population is declining and they may already be extinct in parts of their range.
In parts of their range Darwin’s frog is known as the ‘cowboy frog’ by locals. The reason for this is not clear, it may come from their call sounding like a whistling cowboy or that the spots on their underside resemble those a cow.
These frogs are named for famed naturalist, Charles Darwin who discovered them on a voyage to Chile in 1834.
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Mono Andes, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons
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