Why do birds sing so loudly in the morning in spring? It’s the ‘dawn chorus’

As spring begins, so does a fresh song at daybreak, unique to the season. Just before the sun rises, birds start singing their melodies, creating a chirpy symphony. 

This phenomenon is known as the dawn chorus, and it’s special for a number of reasons: There are more birds singing at this time of year, and they also sing more often. This energetic burst of birdsong is often louder than usual too. The dawn chorus’ early morning explosion of sounds has even inspired multiple poems and songs. 

“It’s the epitome of spring,” says Jordan E. Rutter, an ornithologist at the American Bird Conservancy. After the long and cold winter, “all of a sudden you have this influx of so many beautiful birds coming back and singing.”

This harmony of birdsong at dawn happens during a fundamental time of the year. The dawn chorus is, in fact, mostly composed of birds of both genders singing to find a mate so they can breed (though males may sing more). 

“There is such a large increase in quantity of song by individuals and the collective,” Rutter says. “These birds sing louder to literally be heard. They need to compete with each other as well, and the louder the better in regards to who is the most impressive mate.”

During this time, males also sing to assert their dominance and claim their territory. “Those songs are how they communicate to other males of the same species, or even just other birds and predators in general, and say, ‘This is my home,’” says Rutter.

In the United States and Canada, the dawn chorus can be heard roughly from March through May, when many bird species migrate there from their winter homes to breed. Peak dawn chorus times might depend on where you live, Rutter says. For example, April is peak for the southern U.S., but birds in Washington, D.C., will put on the best show in early May. (Alternatively, in the tropics, the dawn chorus can be heard almost any time of year, as many birds have a prolonged breeding season in those warmer climates.)

Why is it a ‘dawn’ chorus?

But why birds sing in the early morning is still “an open question,” says Mike Webster, an ornithologist at the Cornell Lab of Ornithology. “There’s a lot of debate, and I don’t think there’s any consensus on exactly why it is that everything happens at dawn.”

One hypothesis is that weather conditions at daybreak make it easier for birdsong to travel. 

“In general, sound travels farther when the air is cooler and more dense. Sound also transmits more clearly (and very slightly faster) when humidity is higher so that details of the song do not degrade as much over distance,” says Heather Williams, a professor at Williams College who has studied the neuroscience of birdsong. She notes that wind may also impede sound transmission. “At dawn, the cooler air results in decreased winds at ground level, so coupled with the higher humidity, sound carries farther and more clearly, with less distortion.”

It may also be that in the morning, after the night has passed, male birds want to inform their rivals that they’re still there, claiming their territory.

During the dawn chorus, each singer has their own entrance time, too. “Each species tends to have a very specific time or amount of time before sunrise when they start singing,” says Webster. Some birds, for example, will start chirping 45 minutes before the sun comes up, others half an hour. “It’s really very precisely timed.”

Some species even have songs that they perform only during the dawn chorus, according to Webster. This unique symphony resonates in every habitat where songbirds live, from deserts to forests to grasslands. Among those, warblers, thrushes, vireos, orioles, grosbeaks, and flycatchers are some of the most iconic birds you can hear.

But how do the birds understand other individuals of their own species among all the noise? “Birds are very good at picking out the songs of their own species,” says Webster. “Even though there’s lots of other species singing, making it hard for them to hear each other, they still can pick up on each other’s voices.”

How to tune in to bird radio

Witnessing the dawn chorus can be a rewarding experience, but this phenomenon can also help scientists working on bird conservation. “Listening to birdsong is a window into the health of the species and the health of the ecosystem,” says Webster. For example, scientists record the dawn chorus to understand which species live in an area, or how populations are faring. “You can get a gauge of the health of the ecosystem by who’s participating in the dawn chorus,” he adds.

Fortunately, anyone can listen in. This spring, just wake up early, bring a cup of coffee, head out into nature (even just in your backyard), and stand still and listen. 

“You don’t need to know how to identify bird calls or songs to just appreciate them,” says Rutter. “It’s the most natural soundtrack on Earth, which is just so wonderful.”