Amphibians
Pacific Chorus Frog
Pseudacris regilla · also called Pacific chorus frog, Pacific tree frog, Pacific treefrog
The Pacific chorus frog is the most heard and least recognised amphibian in the world. Its two-note call is the “ribbit” dubbed into nearly every night scene in film history, recorded in the hills above Hollywood — even though almost no other frog on Earth actually says “ribbit.”
Overview
Pacific chorus frogs live across western North America from British Columbia to Baja California, from sea level to the mountains. They are tiny (2–5 cm), come in green, brown, grey, or bronze with a dark eye stripe, and hunt flies, beetles, ants, and spiders at night. They breed in almost any shallow water — ponds, ditches, tyre ruts, flooded fields.
The Hollywood ribbit
The male’s “kreck-ek” call was recorded in the canyons around Los Angeles from the early sound-film era and mixed into night scenes set anywhere in the world. Audiences heard it so often that “ribbit” became the sound a frog makes — when in reality frogs trill, bark, whistle, grunt, and scream.
Colour change
The frog shifts between green and brown over minutes to hours by moving pigment in its skin cells, cued by background and humidity. Each individual has a limited personal range.
Why it thrives
It is a generalist — broad diet, wide temperature tolerance, fast breeding, and happy in puddles and suburbs — so it stays abundant where fussier amphibians have vanished.
Status
The Pacific chorus frog is Least Concern and one of the most common frogs on the Pacific coast.
Pacific Chorus Frog: common questions
Do frogs actually say "ribbit"?
Almost none of them do — "ribbit" is essentially one species' call that became the global stereotype through the movies. The two-syllable "ribbit" (more accurately written "kreck-ek") is the advertisement call of the male Pacific chorus frog, a small frog abundant in the canyons around Hollywood. From the earliest days of sound film, studios recorded ambient night sounds in those hills, and the chorus frog's call was mixed into the soundtrack of night scenes regardless of where the story was set — a swamp in Florida, a jungle in Africa, a pond in England. Audiences heard it so often that "ribbit" became the accepted sound a frog makes, even though the thousands of other frog species produce trills, barks, whistles, grunts, clicks, and screams instead.
How does the Pacific chorus frog change colour?
It moves pigment within specialised skin cells. Chromatophores in the frog's skin contain granules of dark melanin and other pigments, and by spreading those granules out or clumping them together the frog darkens or lightens and shifts between greenish and brownish tones. The change takes minutes to a couple of hours, not the near-instant switch of a cuttlefish or a chameleon, and it is driven mostly by temperature, moisture, and the colour of the background the frog is resting on. Each individual has a limited personal range — a frog that is naturally green will not turn deep brown — but within that range the ability helps it stay inconspicuous as it moves between leaves, bark, and soil.
Is it a tree frog or a chorus frog?
Both names are used, and the confusion is real. Historically it was called the Pacific tree frog and placed in the genus Hyla with other tree frogs. Genetic work later moved it into Pseudacris, the chorus frogs, which are generally smaller, more terrestrial relatives, and the common name was updated to Pacific chorus frog. Physically it looks and behaves like a tree frog — it has expanded sticky discs on its toes and readily climbs vegetation — but it also spends a lot of time on the ground and in low cover like a typical chorus frog. Many field guides and biologists still use "Pacific tree frog," so the two names refer to exactly the same animal.
Why is this frog so common when many amphibians are declining?
The Pacific chorus frog is a generalist, and generalists cope with human-altered landscapes far better than specialists. It will breed in almost any shallow, fish-free water that lasts a few weeks, including artificial ones; it eats a broad range of small invertebrates; it tolerates a wide span of temperatures and moisture levels; it matures quickly and produces large egg clutches; and it does not depend on old-growth forest or pristine streams. As a result it remains abundant across suburbs, farmland, and disturbed habitat where more sensitive frogs and salamanders have disappeared. It is not immune to threats — it can carry and be affected by the amphibian chytrid fungus, and roadkill and pesticide runoff take a toll — but its ecology makes it resilient.