Coquí or Bird? What You Are Hearing at Night in Puerto Rico

The rhythm test: coquís do not improvise

The common coquí (Eleutherodactylus coqui) is nocturnal, and its call is a rapid, loud ko-KEE that gives it its name. Males give it to attract mates and during aggressive encounters with other males. The key to separating it from a bird is regularity: the same phrase, with the same length, repeated over and over, almost always with other coquís answering nearby.

Night birds rarely sound like a line of identical voices in every shrub. A Puerto Rican Owl or Nightjar is usually one voice, or two answering each other, coming from a fixed point and pausing for stretches. If the sound seems to come from everywhere at once and never stops, think frogs or insects first.

Not every coquí says 'coquí'

Puerto Rico has several coquí species with different calls, and some do not sound like their name. The endangered coquí llanero, known from a single freshwater wetland in Toa Baja, gives series of short, very high notes between 7.38 and 8.28 kHz, the highest frequency among the island's coquís. That makes it hard to detect by ear.

That species also breaks the idea that frogs call only late at night: its activity starts around 4:30 p.m. and drops sharply before midnight. An automated-recorder study in Puerto Rico (Ospina and colleagues, 2013) found that frog calling activity responds to daily rain and temperature; a humid night after a downpour can sound very different from a dry one.

The birds that do call at night

In the public collection of Puerto Rico recordings, the Puerto Rican Owl has 20 timed recordings, from 7:00 p.m. to 6:35 a.m., at places as different as El Yunque, Guánica, Maricao, Ceiba, and Arecibo. The Puerto Rican Nightjar appears mostly between 6:30 and 8:30 p.m. at Guánica, Yauco, Lajas, and Susúa, which is where it lives: dry forest and scrub in the south and southwest.

The Antillean Nighthawk calls in flight over open ground with a dry, repeated killy-ka-dick; on the island it has been recorded at dusk and at night in Carolina, Guánica, Lajas, and Río Grande. The Yellow-crowned Night Heron gives a loud quawk, higher than a Black-crowned Night Heron's, and feeds at dusk and at night, though also by day. None of them repeats a ko-KEE.

The confusing case: a mockingbird at midnight

If you hear a bird singing varied phrases at 1:00 a.m. under a streetlight, it is most likely a Northern Mockingbird (Ruiseñor). Audubon notes that it regularly sings at night, and unmated males do so especially at full moon or near lights. It also imitates other sounds, including insects and frogs.

The clue for separating it from a real coquí is variety: a mockingbird repeats a phrase several times and then switches to a completely different one. A coquí never changes repertoire. If the voice jumps from whistles to clicks to something like a car alarm, it is a bird.

Five questions to decide in the dark

One: how many identical voices are there? Many suggests frogs or insects; one or two, a possible bird. Two: where is it coming from? Low plants near the ground point to a coquí; a moving voice overhead, to a nighthawk; a fixed tree in forest, to the owl. Three: does the phrase change? If it changes a lot, think mockingbird.

Four: what time is it? Dusk and the first hour of night are the nightjar's peak in its dry forest; the pre-dawn hours, the owl's. Five: where are you? A wetland adds night-herons, gallinules, and the Limpkin, which wails at dawn or at night. Write down these answers and record 30 seconds; with that, almost any experienced listener can confirm it.

Which app is for what

Bird platforms such as eBird and the Macaulay Library take bird recordings tied to a species checklist; they are not the place for a coquí recording. iNaturalist, by contrast, accepts verifiable observations with photos or sounds across many groups of organisms, frogs included.

If you recorded a coquí chorus with a Puerto Rican Owl in the background, upload it to eBird for the bird only, without stripping the frogs from the audio: Macaulay Library guidance says not to remove other species' sounds or apply noise reduction. The coquí noise is part of the recording's real context.

Is the coquí a bird?

No. The coquí is a frog in the genus Eleutherodactylus. Its ko-KEE call, given by males at night, is Puerto Rico's best-known night sound, but no bird makes it.

What bird sings at night in Puerto Rico?

The most common are the Puerto Rican Owl in forest and wooded areas, the Puerto Rican Nightjar in the southwestern dry forest, the Antillean Nighthawk flying over open areas, and the Northern Mockingbird under city lights. At wetlands, night-herons and the Limpkin call too.

How can I tell if it is a coquí or a bird?

A coquí repeats the same short phrase without variation, from low vegetation, in a chorus with many others. A night bird is usually a single voice from a fixed point that pauses, or, in a mockingbird's case, one that changes phrases often.

How loud is the coquí?

In Hawaii, where the coquí is invasive, calling males were measured at up to 73 decibels, enough to cause complaints about lost sleep. In Puerto Rico it is native and part of the natural soundscape.

What does the Puerto Rico barn owl sound like?

The Puerto Rican Barn Owl is extinct and known only from cave remains, so there are no recordings. The American Barn Owl is listed as accidental on the island; the night bird almost everyone hears is the endemic Puerto Rican Owl.

What does the Puerto Rican nightjar sound like?

The Puerto Rican Nightjar sings in the dry forest and scrub of the south and southwest; its timed recordings cluster at dusk and in the first hour of night. Listen to the recordings on its profile, made at Guánica, before you go, and do not use playback: it is an endangered species.