STEVE INSKEEP, HOST:
And let's take a moment to listen to the sounds of your backyard, or one like yours.
(SOUNDBITE OF WHISTLING)
DAVID GREENE, HOST:
OK, that's not actually a bird whistling reveille. But when we invited people to send us sounds of nature, we heard sounds that were distinctive enough. [POST-BROADCAST CORRECTION: In the audio of this story, we misidentify a tune as reveille; in fact, it's assembly.]
INSKEEP: Each sound is a little mystery made by a species that we try to identify. And the sound that J.P. Kennia (ph) heard on Cape Cod was kind of creepy.
(SOUNDBITE OF GREAT HORNED OWL)
GREENE: Creepy, indeed. His private name for it was simply dinosaur bird. He heard it this summer in Chatham, Mass. He guessed it might be some kind of owl. To find out for sure, we called an expert.
JESSIE BARRY: J.P. is correct. This is a juvenile great horned owl.
INSKEEP: That's Jessie Barry of the Cornell Lab of Ornithology. She says her office gets many notes asking about this common bird, which sounds nothing like a cartoon owl asking, who (ph).
(SOUNDBITE OF GREAT HORNED OWL)
INSKEEP: This owl sounds hungry. When an owl gets really hungry, it can screech like a fussy toddler.
BARRY: It's this loud screech that really sounds like they're almost just saying, mom, mom, I'm over here, and I'm hungry.
GREENE: This screech is most common in the spring and summer months when baby owls are growing up. They're almost ready to leave the nest but still expect their parents to feed them.
BARRY: Great horned owls start nesting pretty early in the year, and it takes, you know, weeks for the chicks to grow up in the nest. And then once they start to leave the nest, that's when they begin to give this vocalization.
INSKEEP: And even though great horned owls can sound spooky, Barry says they're not.
BARRY: It sounds kind of scary, but we are very safe. And great horned owls are going to be trouble for a skunk or a raccoon but not for us.
GREENE: At least we hope. That is Jessie Barry from the Cornell Lab of Ornithology helping us decode the eerie screech of the great horned owl. If there's a wildlife sound that you want some help identifying, use your smartphone to record at least a minute or two of the natural world in your backyard.
INSKEEP: Send the file to nprcrowdsource@npr.org with the subject line, decode nature, as well as your location. And for more on this project, follow the hashtag #DecodeNature on Twitter. Transcript provided by NPR, Copyright NPR.