What bird sounds like a frog?

A bird that sounds like a strange frog in a marsh at dusk or after dark is most likely an American Bittern, a hidden heron whose breeding-season call is a deep, gulping oong-KA-chunk that carries for half a mile. In a yard, a hedge or a park, a frog sound dropped into a long, rambling song is more likely a Gray Catbird or a Northern Mockingbird, two birds that copy frogs along with everything else. And sometimes, honestly, it is a frog.

The likeliest bird: an American Bittern in the marsh

The American Bittern is a classic case of a frog that turns out to have feathers. A California nature columnist, writing about bitterns at Sacramento National Wildlife Refuge, admitted that the first time she heard one, she assumed it was some odd frog, and was astonished to learn it came from a bird. Audubon writes the call as oong-KA-chunk, a loud pumping sound repeated a few times and often audible half a mile away, usually at dusk or at night.

How the bird makes it explains why it sounds so un-birdlike. The male clacks his bill, gulps air into his esophagus until it swells, then forces the air back out past the voice box while pushing his head down and out. The result is part gulp, part boom, part burp, which is how the bird earned folk names like thunder pumper and water belcher. Males use it to advertise and defend a nesting territory.

You will hear a bittern far more often than you see one. It is a stout, solitary heron that lives in large freshwater marshes with tall cattails, sedges and grasses and patches of open shallow water, and it tends to stand still at the edge of the reeds or slip through them unseen. In flight it gives a low kok-kok-kok. Most bitterns migrate; in winter they use similar marshes plus brackish coastal ones.

The mimics: a frog in the hedge

If the frog sound came from a yard, a thicket or a rooftop in daylight, and other sounds came before and after it, you are probably listening to a mimic.

The Gray Catbird copies other birds, mechanical sounds and tree frogs, and works them into a raspy, rambling song sung from inside a bush. It sings most phrases only once, so the frog goes by in a moment and the bird is on to something else. Listen for the catlike mew call between songs, which gives the singer away.

The Northern Mockingbird copies frogs and crickets as well as cats, dogs and many other birds, and a male may know anywhere from 43 to 203 song types. Unlike the catbird, it hammers each phrase three or four times before switching. Mockingbirds live year-round across nearly all of the continental United States, and the males start singing in late January or February and keep it up into summer. Unmated males in particular like a high perch.

How to tell which one you heard

• A deep, gulping boom from a big marsh at dusk, repeated a few times, then silence: American Bittern.
• A brief froggy note inside a long, raspy song from a bush, with a mew now and then: Gray Catbird.
• A frog sound repeated three or four times, then a totally different sound, from a high perch: Northern Mockingbird.
• Many voices at once from a pond or wet woods on a warm night, each one repeating the same note: probably the frogs themselves.

If you are near a wetland, the bittern is the answer worth waiting for. If you are in a backyard, record a minute of the song and let Warble name the mimic doing the frog.

Questions people ask

Warble is a game, not a field guide. Facts about birds on this page come from the sources above.