Swan

“Mute” is misleading

The mute swan is named for being quieter than other swan species, particularly the noisy whooper and trumpeter swans. But it’s not silent — agitated mute swans hiss loudly, grunt, and snort. Cygnets (chicks) make piping calls to their parents. The most acoustically distinctive feature is the wing music — a whirring sound produced by the wings in flight, used by birds in formation as a navigation cue.

A possessive bird

Mute swans are famously territorial during breeding season. They aggressively defend their nesting area against geese, ducks, dogs, kayaks, and even humans. A swan attack can drive a person off a footpath or capsize a small boat. The attacks rarely cause serious injury, but the warning hisses, the wing-flap displays, and the willingness of a 14 kg bird to charge are intimidating.

This aggression has made mute swans contentious in places where they’ve been introduced — they outcompete native waterfowl by physically chasing them off entire lakes.

English crown property

In the United Kingdom, all unmarked mute swans on open water belong by law to the Crown — a tradition dating to at least the 12th century, when swans were a status food at royal banquets. The annual Swan Upping ceremony on the Thames still surveys swan populations and assigns ownership in a tradition unbroken for over 800 years.

Lifelong pair bonds (mostly)

Mute swans are known for forming long-term, often lifelong pair bonds. Pairs typically remain together year-round, defending a territory and raising broods together. When a partner dies, the survivor sometimes takes a new mate quickly; sometimes years pass before another pairing.

The “mate for life” reputation is partly real and partly storytelling — divorce does occur, especially after several failed breeding seasons.

Other swan species

Six other swan species exist worldwide:

• Trumpeter swan (Cygnus buccinator) — North America; recovered from near-extinction.
• Whooper swan (Cygnus cygnus) — Eurasia; very loud bugling call.
• Tundra/Bewick’s swan (Cygnus columbianus) — Arctic breeders.
• Black swan (Cygnus atratus) — Australia; entirely black plumage.
• Black-necked swan (Cygnus melancoryphus) — South America.
• Coscoroba swan (Coscoroba coscoroba) — South America; sometimes considered a goose-swan intermediate.

The discovery of black swans in Australia in 1697 famously upended European philosophy’s assumption that “all swans are white” — a discovery now used as the namesake for the Black Swan concept of unforeseeable improbable events.