Why Do Birds Sing in the Morning? The Dawn Chorus Explained

What is the dawn chorus?

The dawn chorus is the burst of bird song that begins before sunrise and peaks around sunrise, especially in spring. In the Northern Hemisphere it is loudest from about April to June, when birds are breeding and migrants have returned from the south.

The first birds usually start singing about an hour before sunrise, while the sky is still dark. More species join as the light grows, until dozens of birds may be singing at once. After sunrise the chorus fades, although birds keep singing on and off through the day.

In most temperate songbirds, the singers are mainly males. Song tells rival males to stay away and tells females that a healthy, territory-holding male is available.

Why sing at dawn rather than later?

Scientists have tested several explanations. None explains everything on its own, and different factors probably matter for different species.

• It is too dark to feed well. Insects are hard to see and often inactive in the cold dawn air. Instead of wasting effort looking for food, a bird can put the time into singing.
• Proving fitness after the night. Small birds use up a large part of their fat reserves keeping warm overnight. A male that sings hard at first light shows rivals and females that he is in good condition. Experiments with extra food suggest that well-fed birds sing more at dawn.
• Reclaiming territory. Some territory holders die overnight. Early morning is when vacancies appear and when newcomers may try to move in, so resident males sing to reassert their claim.
• Guarding a fertile mate. In many songbirds, females lay eggs in the early morning and are most likely to mate around dawn. Singing then may help males attract a partner, deter rival males and guard their own mate.
• Sound travels well. Dawn air is often still, cool and calm, with little wind or background noise. Some studies have found song carries better then, although the evidence is mixed and this is now seen as a smaller factor.

Which birds sing first?

The dawn chorus has a fairly consistent order. Research in Britain and South America has found that species with larger eyes, which can see better in low light, tend to start singing earlier. Birds that perch and feed higher in the trees, where light arrives first, also tend to start sooner.

In Britain and much of Europe the first singers are usually:

• European robins, which may start more than an hour before sunrise
• Blackbirds and song thrushes
• Wrens, whose loud song carries far in the half-light
• Later, tits, chaffinches and warblers

In eastern North America, the American robin is one of the earliest singers, often joined by the northern cardinal, song sparrows and mourning doves, with many warblers and finches coming in later.

How the chorus changes through the year

In winter most birds sing little in the morning. Exceptions include the European robin, which sings all year, and in North America the northern cardinal, which begins singing on mild late-winter days. As days lengthen, rising hormone levels trigger more song, and the chorus builds through late winter into spring.

The chorus is richest in late April and May in Britain, and May and early June in much of the northern United States and Canada, when residents and returning migrants are all singing. After eggs hatch, parents spend more time feeding chicks, and from July the chorus quiets down. In late summer, when many birds molt, mornings can be surprisingly silent.

Do birds sing at dusk and at night?

Many birds also sing around sunset, forming a smaller dusk chorus. Robins and blackbirds are often among the last singers of the day.

A few birds sing at night. Nightingales and some reed warblers do so naturally, and the northern mockingbird is famous for night song in North America. In towns, artificial light and daytime noise push some birds, especially robins, into singing in the dark. That story is told in why do robins sing at night?.

How to enjoy the dawn chorus

The best time to listen is a calm, dry morning between late April and early June, from about an hour before sunrise. Woodland edges, parks and large gardens are good places. International Dawn Chorus Day, on the first Sunday in May, began in Birmingham, England, in 1987 and is now marked with early bird walks in many countries.

Try picking out one voice at a time. The robin’s thin, wistful warble, the blackbird’s slow, mellow fluting and the cardinal’s loud, clear whistles are a good place to start.