Why did the birds stop singing? What happens in late summer

Birds stop singing in late summer because song is a breeding tool and breeding is over. Its two main jobs are attracting a mate and holding a territory, and both are driven by hormones that rise with the long days of spring and fall away once the young have fledged. At the same time most adults begin their annual molt, replacing every feather, which is costly and leaves them quieter and more hidden. The young birds beg rather than sing, and the migrants slip south at night. The chorus does not return until the days lengthen again in late winter.

Song is a breeding-season tool

It helps to separate two kinds of bird noise. Songs are the long, complex performances tied to courtship and territory. Calls are short notes for alarms and for keeping a flock together. When people say the birds have gone quiet, they mean the songs.

Song runs on hormones. Experiments on canaries showed that females given androgens (the family that includes testosterone) began singing at almost male rates, and the song centers of their brains grew. In wild songbirds those hormones track day length: spring's lengthening days switch the system on, and as the young leave the nest the levels fall and the urge to sing falls with them. A New Hampshire naturalist's summary is blunt: in spring you might hear ten to twenty kinds of birds singing at once, and by late August the silence is the story.

Nothing left to defend

A male sings in April to claim a patch of woods and to talk a female into it. By July that job is done. The pair has a nest or has emptied one, and the parents spend their days hauling food to chicks instead of advertising. Audubon's summary of the season is that most birds are hunkered down, finishing the work of raising young, with no urgency to call attention to themselves.

Species that raise several broods, like the American Robin, the Eastern Phoebe and the Song Sparrow, sing in bursts, going quiet between nests and picking up again for the next one. That is why a robin that stopped in June sometimes returns for a week in July.

Molt: quiet and hidden

The second reason is a wardrobe change. Most birds replace their feathers once a year, and the main molt comes right after breeding, while food is still plentiful. It is expensive: feathers make up somewhere between four and twelve percent of a bird's body weight, and growing a full new set takes real energy. Songbirds shed gradually and symmetrically, a few feathers from each side at a time, so they can still fly, but a bird with gaps in its wings and tail is slower and more exposed.

So a molting bird does exactly what you observe: it stays low in the thickets, keeps quiet, eats, and waits. The cardinal that sang from the top of the maple in May is now working through the underbrush and saying almost nothing.

The young beg, they do not sing

Most songbirds fledge from late June through July, and a fledgling does not sing. It begs. The insistent, whiny note repeated for minutes on end in the August hedge is usually a young bird following a parent and demanding food. Look for a fluffy, slightly dazed bird with a short tail, an oversized bill and pale corners to its mouth, moving clumsily from branch to branch. Juveniles wear that plumage for less than a month, and the begging fades with it.

Migration happens at night, mostly in silence

Many of the loudest spring singers, the warblers, tanagers, orioles and thrushes, are gone by September, and they leave without a farewell concert. Warblers, tanagers, orioles and sparrows migrate at night, when hawks are not hunting, and the thrushes that sang at dawn all June switch in August to short contact calls at dawn and dusk before they go. What remains of their voices is the nocturnal flight call: a brief note given in the dark so that birds of the same species can keep together. Sit outside on a clear September night and you may hear them passing overhead.

What you still hear

Late summer is not silent so much as changed.

Add the American Crow, and the chickadees and titmice, whose contact calls hold their flocks together in the woods. Vireos and wood-pewees are the last summer singers, some still calling into September and October.

A small second season in fall

There is one more twist. As the days shorten in September, the change in light nudges the hormones again, and some resident birds sing a little: not the spring performance, but a few phrases at dawn. In New England, cardinals, chickadees and titmice do this, and Song Sparrows that stay for the winter continue to defend a territory. The message, roughly: I am still here, this is still mine. A full song in fall is almost always a bird that lives on your street all year.

When the singing comes back

Sooner than you think. The trigger is day length, not temperature, so the first songs arrive in late winter while there is still snow. Cardinals begin trying out their whistles in the middle of January, the Tufted Titmouse gives its peter-peter during midwinter thaws, and in the South mockingbirds can be nesting, and singing, before winter is officially over. The migrants add their voices in April and May.

The quiet months are a good time to learn the calls, since there are no songs to drown them out. Warble hears a cardinal's chip or a jay's scream as readily as a full song, so a walk in September still adds birds to the album.

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Warble is a game, not a field guide. Where this page states a fact about a bird, it comes from the sources above.