Why Are Mute Swans Called Mute? Swan Sounds Explained

Where the name “mute” comes from

The mute swan was named by comparison with its noisy relatives. In northern Europe, people who knew the whooper swan, a winter visitor with a ringing, trumpet-like call, noticed that the resident swans on their rivers and lakes rarely called at all. “Mute” was a relative description, meaning quiet, and it stuck.

The scientific name is less helpful: Cygnus olor simply means “swan swan,” because both cygnus and olor are old words for swan.

What sounds do mute swans make?

Spend time near a pair of mute swans and you will hear quite a lot:

• Hissing: the classic warning. A swan pulls its neck back, opens its bill and hisses at intruders that come too close to its nest, partner or cygnets.
• Snorts and grunts: short, hoarse sounds used in contact between partners and during disputes.
• Soft calls during courtship: pairs make rhythmic, quiet sounds while performing head movements together, which seem to help them coordinate their displays.
• Cygnet calls: young cygnets are noisy, giving contented whistles and peeps, and harsher, more urgent cries when they are lost or cold.

These sounds are soft compared with other swans and travel only a short distance, which is why many people never notice them.

The sound of mute swan wings

The most famous mute swan sound is not a call at all. In flight, its wings make a loud, rhythmic throbbing or whistling hum, often written as “vaou, vaou, vaou.” The sound is produced by air passing over the stiff flight feathers with each wingbeat and is unique to this species among swans.

The wing noise can be heard from 1–2 km (0.6–1.2 mi) away. Because mute swans call so little in the air, biologists think the throbbing works as a contact signal, letting members of a flying group or family keep track of each other. Other swans fly almost silently and rely on their voices instead.

Why are other swans so much louder?

The difference is partly anatomy. Whooper, trumpeter and tundra swans have a very long windpipe, or trachea, that loops into a hollow inside the breastbone before reaching the lungs. Like the tubes of a brass instrument, this long, coiled windpipe helps produce loud, resonant, far-carrying calls.

The mute swan’s windpipe does not form this loop inside the breastbone, so it cannot make the same booming sounds. Its quieter habits also suit its lifestyle. Many mute swans live year-round on a single territory and do not need to keep flocks together over long migrations, as the Arctic-breeding swans do.

Whooper and trumpeter swans: the noisy cousins

The whooper swan (Cygnus cygnus) breeds in Iceland, Scandinavia and northern Russia and spends the winter in Britain, Ireland and western Europe. Its name comes from its loud, bugling whoop, and flocks can be heard long before they are seen.

The trumpeter swan (Cygnus buccinator) of North America is the continent’s largest native waterfowl. Its deep, horn-like call gave it both its English name and its scientific name, from bucina, a Roman trumpet. Mated trumpeter swans often call in duet, and their calls carry across wetlands for long distances.

For other remarkable callers, from howler monkeys to blue whales, see our list of the loudest animals.

Do swans sing before they die?

The phrase “swan song” comes from an ancient Greek belief that swans, silent through life, sing a beautiful song just before they die. The legend was repeated by writers for centuries, but there is no reliable evidence that mute swans, or any swans, do this. Today “swan song” is just a figure of speech for a final performance.

How to recognize a mute swan by sound and sight

If you hear a deep, rhythmic throbbing overhead, look up: it is almost certainly a mute swan in flight. On the water, a swan that is silent most of the time, holds its neck in an S-curve and has an orange bill with a black knob is a mute swan. A swan with a straight neck, a black and yellow bill and a loud bugling call is a whooper. Mute swans may be quiet, but they are rarely shy. To learn how they defend their families, read can a swan break your arm?