How to identify a bird song online (or from a recording)

Two tools can analyze a recording you already have. Merlin Bird ID, the Cornell Lab's app for iPhone and Android, can import an audio file such as an mp3, m4a or wav and suggest the species. BirdNET's browser demo takes a WAV or MP3 file and analyzes it inside your web browser, with nothing uploaded. Then check the suggestion against reference recordings in the Macaulay Library, xeno-canto or Audubon's online field guide, look up the sound by description, or ask other birders. Recording live with an app on your phone is easier still.

Tools that analyze a recording you already have

Merlin Bird ID, on your phone

Merlin's Sound ID usually listens live, but it also takes files. In Sound ID, tap import and choose an audio file, or share a file to Merlin from another app. Cornell's help page lists mp3, m4a and wav among the formats, depending on what your phone supports. Merlin runs on Android and iOS phones and tablets, not on desktop computers, so a clip on your laptop needs to reach your phone first. It identifies more than 2,000 species by sound, most strongly in the United States, Canada and Europe.

BirdNET, in a web browser

This is the closest thing to a true online bird song identifier. BirdNET, a collaboration between the K. Lisa Yang Center for Conservation Bioacoustics at Cornell and Chemnitz University of Technology, has a demo page that runs its model inside your browser. You drop in a WAV or MP3 file, or record from the microphone for up to five minutes, and the results appear on the page; you can download them as a spreadsheet file. The page is clear that the audio is processed in the browser and nothing is uploaded. Turn on the location filter, which is off by default, so the list leans toward species likely where you are. BirdNET's newer phone app, BirdNET Live, can also analyze files stored on your phone.

A practical snag: neither page mentions video files. If the song is in a video, save or export the audio on its own before you try either tool, and trim it to the part where the bird is loudest.

Compare against reference recordings

Once you have a candidate, or even just a hunch, listen to known recordings of that bird and play your clip right after. Three libraries are worth knowing.

• The Macaulay Library is part of the Cornell Lab of Ornithology, with recordings covering 96 percent of the world's bird species; you look them up through its Media Search catalog. Cornell trains Merlin on recordings from it.
• xeno-canto is a volunteer project, online since May 30, 2005, that holds more than a million sound recordings of over 12,900 species: birds, plus grasshoppers and their relatives, bats, frogs and land mammals. Anyone can upload, and the recordings are published under Creative Commons licenses.
• Audubon's online field guide has species pages with a Listen section of songs and calls and a written description of the voice, handy for checking what you hear against what the experts wrote.

When you compare, listen for the shape rather than the tone, because a phone recording from across the yard will never sound like a studio clip. How many notes? Does the phrase repeat, and how many times? Does it rise, fall or stay flat? A familiar backyard puzzle shows why that works:

Describe the sound and look it up

Sometimes the recording is too faint to analyze, but you remember the sound perfectly. Put it into plain words: it mewed like a cat, it said its own name, it screamed at night, it sounded like a squeaky wheel. A description like that, plus where and when, is often enough to narrow things down.

The sound finder on this site is built for exactly that. It lists birds by what they sound like, with recordings to confirm: for example a bird that sounds like a cat or a bird that says cheeseburger. Add the season, the time of day and the habitat, and the list of suspects gets short fast.

Ask people who know

Birders tend to be generous with mystery recordings. A local bird club, a regional birding group online or the most bird-obsessed person you know may well name your clip faster than any app. Give them what an app would want: the date, the place, the habitat, the time of day, and the clip trimmed to the bird.

Communities are also how the reference libraries stay honest. On xeno-canto, users can flag a recording they think is misidentified, and the community discusses it until there is agreement, usually within a few days. That is the same skill you are borrowing when you post your clip.

Why recording live is easier

Every method above works harder than it needs to, because an old clip has lost its context. A live bird gives you another chance: you can step closer, wait for a cleaner phrase and record again. The app also knows where you are. Merlin weighs the species likely in your area and works best with location services on, and BirdNET's browser filter only narrows by place if you switch it on. A voice memo forwarded by a friend often carries none of that.

Live apps also show suggestions while the bird is still singing. Merlin lists names in real time with example recordings you can play on the spot, so you can check the match before the bird flies off. Warble uses the same live approach for its game: you tap the button while the bird sings, the phone compares the sound against 800 US species with no signal needed, and a named bird becomes a card in your state's album. One catch a day is free.

Next time you hear something you cannot place, skip the voice memo and open a listening app instead. You will have a name, and a reference recording, before the song ends.

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Questions people ask

Warble is a game, not a field guide. Where this page states a fact about a bird, it comes from the sources above.