This free app is helping millions of people discover the hidden lives of birds

I’m not a bird watcher, but I’ve become a bird listener ever since downloading a bionic ear app to my phone. It lets me enter a different world, one where I’m surrounded not just by chirping but by Black Phoebes, White-breasted nuthatches, Northern flickers and Dark-eyed juncos.

It’s magical.

I’ll admit, I’m horrible at identifying, or really even spotting, birds. Friends eagerly point at a tree saying “Look, a Pileated woodpecker!” and all I see is a blur. Or “A California Towhee!” and all I see are a bunch of branches. They pass me binoculars and I get nauseous from the movement.

Let’s face it, I lack the pattern-recognition knack that makes birding fun.

That all changed when I downloaded the Merlin Bird ID app from the Cornell Lab of Ornithology. I originally added it to my phone to try to identify a bird I’d actually managed to see (a Steller's Jay so blue even I couldn’t miss it). Then I turned on the Sound ID.

Whoa.

I was immediately immersed in a new reality, one bursting with birds I’d never paid attention to because they were invisible to me. Imagine being plunked down onto a street in Paris where there's a wild swirl of language going on around you. And then someone throws a switch and you understand them all.

How does Merlin Sound ID work?

Here's how it works: First you download the free app to your phone. When you hear birds, you open the app and hit "Sound ID" and then the microphone button. The app starts listening for birds, and when it hears and identifies one, it pops up a line with the name of the bird and a photo. It can sort out even if multiple birds are singing at the same time.

From my back porch just now, it heard Chestnut-backed chickadees, House finches and Bushtits, all the while ignoring truck, car and bus sounds as well as nearby roofers, a distant jackhammer and someone's leaf blower. Even in the city, it did a great job.

When you stop recording, you can tap each bird to get a photo and more information.

Suddenly I know the birds that chirp in a tree across the street each morning were House finches, and the quiet peeping I’d heard in the backyard was a Golden-crowned sparrow. When I walked in the park by our house I was awed to realize the hoots I kept hearing were not just one but two kinds of owls – Great horned and Barn.

I am not the only person to be entranced by this. The sound portion is the most popular part of the Merlin app, said Alli Smith, Merlin project coordinator at the Cornell Lab of Ornithology. In the past 30 days, 2.5 million people used Merlin's Sound ID app while 500,000 used the Photo ID, she said.

'Really good at identifying birds by sound'

Merlin's Sound ID can identify 1,054 bird species. It's based on the Macaulay Library, which contains 2 million recorded bird songs from around the world that are then annotated by a team of bird experts.

"They're really, really good at identifying birds by sound," said Smith. When you use the app, you also see a representation of the audio waveform scroll across the screen. "The experts physically draw a box around the part of the file where the bird is singing," she said. That allows the program to tie a song to a given species.

Multiple recordings are important because birds sound different depending on the time of year and geography. "Carolina wrens sound totally different in New York than in Georgia. We want to make sure we capture them all so we don't accidentally train Merlin to recognize only New York Carolina wrens," she said.

It's a time- and labor-intensive process. For each species, the experts listen to about 150 different recordings, which they tag so the program can learn them. For some species that can go as high as 400.

Bird mistakes

Merlin is not perfect, and it can get confused. That's one reason it asks to access your location, so it knows what birds are likely to be around. Here in San Francisco, I'm probably not hearing a Black-capped Siskin (which lives in Guatemala.)

Smith's dog makes a whining sound when he sees a rabbit outside that routinely confuses the app. And a week ago mine told me a Rec & Park truck backing up to a pile of wood chips was a Peregrine falcon.

But I'll admit that when I listen to the examples of an actual Peregrine falcon Merlin thoughtfully provided, it was an honest mistake – they sound remarkably similar. And that identification had a red dot next to it, telling me that it would be rare for a species to be seen where I was.

It's not cheating

Just to be clear, using Merlin Sound ID isn't cheating at bird watching. Because there is no cheating when it comes to learning to appreciate the avian world, Smith said.

"Merlin is lowering the barrier to entry, making birding less daunting," she said. "It can be intimidating to open a bird book and think, 'Oh my God, there are 7,000 birds in this book and they all look the same!'"

Instead, you can let Merlin be your magic ear. That's where the name of the app actually comes from, because of it's "almost magical way of guessing which bird you saw."

You can of course also do things the old-fashioned way, by sight. Merlin has a series of five questions to narrow things down once you've gotten a glimpse of a bird.

• Where did you see the bird?
• When did you see the bird?
• What size was the bird? (wren, robin, crow or goose-sized?)
• What were its main colors?
• What was it doing?

Answer those simple questions and it will give you list of possible birds to choose from based on your location. But I wasn't surprised to hear that five times more people use Sound ID than the photo ID guide.

Me? I'm content to stick with my magical ear for the time being. Someday I may try to work out which bird goes with what name and sound, but for now it's enough to know the bird I heard when I was out watching agricultural robots down in Monterey was a Pied-billed grebe.