Dear Alexandria,

I usually write answers to kids’ science questions early in the morning. I like how it’s so quiet—except for my bird neighbors singing and singing.

I asked my friend Jennifer Phillips what’s going on. She’s a bird scientist at Washington State University.

She told me birds sing in the morning to tell other birds that their territory still belongs to them.

“The morning time is usually a little bit more calm, especially in windy areas,” Phillips said. “So, it’s a good time to broadcast your song and for that song to potentially travel a little farther.”

A bird’s territory is the area that bird will defend from other birds. Like a sparrow might have a territory full of good places to nest and lots of seeds and berries to eat. If another sparrow shows up on that territory, the first bird will chase him away, so he doesn’t take the resources.

But that sparrow will also have a home range. That’s a bigger area where the bird might forage or hang out—but it won’t defend that space.  We know that because scientists follow birds and map their territories and home ranges.

A bird’s morning song can be a warning to other birds that might want to sneak onto their territory. It can also be an invitation to female birds looking for a good place to nest.

“We think they can tell each other apart based on their voices or their performance characteristics,” Phillips said. “The whole idea of that song is to advertise something about that individual. So, the song should be saying, ‘This is me. Look how good my song is.’”

There might be differences in a bird’s body—like its beak or throat muscles—that make his song different from another bird’s song. But the song also broadcasts information about the bird’s territory. If a bird can sing a long time, that means he has lots of seeds and berries to give him energy. A female bird looking for a good place to raise chicks might like that.

Birds who are already bonded to each other also sing together. That’s called dueting. It’s how bird pairs make sure their bond is solid. It’s also how birds like cardinals communicate with each other when one bird is in the nest and the other is out foraging.

A female cardinal in profile. She' smostly brown, grey and yellow with bits of red on her tail feathers, wings, and crown.
Female cardinals sing longer, more complex songs than male cardinals. Scientists think dueting might be one way she tells her mate to bring food back to the nest.

Phillips told me that there’s one bird—the brown-headed cowbird—that uses song to defend its relationship. If a male bird is part of a pair but keeps singing to attract other mates, the female bird will jam his song. She’ll sing super loud so other birds can’t hear him.

A female brown-headed cowbird sitting on a branch and singing. It's brown.
Brown-headed cowbirds lay lots of eggs. But they don’t spend time building a nest. Instead, they sneak into other birds’ nests and lay eggs there. Then, those other birds raise their chicks. Image: Rhododendrites/Wiki

It turns out we don’t know as much about female birds and their songs. That’s one thing scientists are trying to figure out now—by following and recording female birds to uncover how and why they sing.

I’m sure they’ll spar-row no effort to figure it out.

Sincerely,

Dr. Universe