This is Bird Note. With today's mobile apps and sound libraries, it's never been easier to listen to birds on demand. But that wasn't always the case. Back in the 1920s, Cornell Ornithology professor Arthur Allen wanted to help his students learn bird calls in the classroom.

But back then, bird recordings were practically non-existent.

Fortunately, this was the era of the first Talking Films, and a prominent production company

enlisted Arthur's help to jazz up their movies with bird recordings.

Arthur and the production team hauled their clunky gear to the woods near Cayuga Lake,

but the noisy equipment kept scaring away the birds.

Eventually, it occurred to Arthur to put just the microphone

near a perch popular with song sparrows

and leave the rest of the gear out of view.

In the dawn hours of May 18, 1929,

a little brown bird made history.

That day, Arthur and his team recorded a song sparrow, house wren, and rose-breasted

gross beak.

With today's high-tech recording tools, bioacoustics researchers can eavesdrop on whales underwater,

bats in the air, and more than 11,000 bird species found around the world.

And it all started with a song sparrow.

For Bird Note, I'm Mark Bramhill.