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What the sources say

Mute SwanCygnus olor

Every figure, record and mechanism on the Mute Swan profile was written from a source, and this is the working table behind it: 44 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

The IUCN Red List of Threatened Species 2025

Cygnus olor. The IUCN Red List of Threatened Species 2025: e.T22679839A281844289.

The page saysLeast Concern
The source saysLeast ConcernNote: GBIF copy of the Red List, taxon id checked against the DOI

Source
02

Wood et al. 2024

Wood et al. (2024). Mute Swan (Cygnus olor). Birds of the World.

The page saysBirds of the World says the pair bonds often last for life
The source saysform strong pair bonds that often last for life
The page saysOften, though not always. Birds of the World says males and females form strong pair bonds that often last for life.
The source saysMales (properly called “cobs“) and females (known as “pens“) form strong pair bonds that often last for life.
The page saysMales and females form strong pair bonds that often last for life, and a pair bows and entwines necks each spring.
The source saysform strong pair bonds that often last for lifeNote: vibe.reason; same source as the body claim

Source
03

British Trust for Ornithology

BirdFacts: Mute Swan. British Trust for Ornithology.

The page saysFrom weighings of live birds, adult males average 10.75 kg and females 8.54 kg
The source saysFemale 8.54±1.23 kg (6.3-10.5 kg, N=233) Male 10.75±1.56 kg (8.2-13.4 kg, N=314)Note: Averages from the Body weight table, adults by sex
The page saysA bird that reaches breeding age typically lives 10 years, and breeding usually starts at four
The source saysTypical life expectancy of bird reaching breeding age 10 years with breeding typically at 4 years
The page saysThe oldest bird in the British Trust for Ornithology's ringing records was 29 years old, a record set in 2009
The source saysMaximum age from a ringed bird 29 years, 1 month, 11 days (set in 2009)
The page saysThe grey cygnets turn grey-brown, then white, during their first year
The source saysthe grey cygnets transform through grey-brown into white adults during their first year
The page saysMales are the heavier sex. Across 314 live adult males weighed for the British Trust for Ornithology, the average was 10.75 kg; across 233 adult females, 8.54 kg.
The source saysFemale 8.54±1.23 kg (6.3-10.5 kg, N=233) Male 10.75±1.56 kg (8.2-13.4 kg, N=314)Note: Body weight table, adults by sex; weights are from live birds
The page saysTen years is typical for a swan that survives to breeding age, by the British Trust for Ornithology's ringing data.
The source saysTypical life expectancy of bird reaching breeding age 10 years with breeding typically at 4 years
The page saysThe longest-lived bird in those records reached 29 years, 1 month and 11 days, a record set in 2009.
The source saysMaximum age from a ringed bird 29 years, 1 month, 11 days (set in 2009)
The page saysweightKg: 10.75
The source saysMale 10.75±1.56 kg (8.2-13.4 kg, N=314)Note: task #1114: BTO's live-bird average for adult males; Medium, where the name guess gave Light. Not in a curated matchup

Source
04

RSPB

Mute Swan. RSPB.

The page saysLakes, rivers, canals and sheltered bays across Europe and Asia, introduced in North America
The source saysincluding lakes, rivers, canals and urban park ponds
The page saysMainly aquatic plants, plus grass grazed from nearby fields
The source saysThey feed mainly on aquatic plants, but also graze on grass in nearby fields and meadows.
The page saysDespite the name, mute swans are not silent. They often grunt softly while feeding and will hiss loudly if disturbed, especially when protecting their young
The source saysDespite their name, Mute Swans aren’t actually silent. They often grunt softly while feeding and will hiss loudly if disturbed – especially when protecting their young.
The page saysIn flight, their wings make a whooshing sound
The source saysWhile flying, their wings make a dramatic whooshing sound
The page saysNewly hatched cygnets often hitch a ride on their parents' backs for warmth, protection and to save energy.
The source saysNewly hatched cygnets often hitch a ride on their parents’ backs for warmth, protection and to save energy.
The page saysIn spring, pairs bow to each other with wings held aloft, then entwine their necks, often forming a heart shape
The source saysEach spring, pairs perform a beautifully synchronised courtship display out on the water, bowing to each other with wings held aloft, before entwining their necks, often forming a heart shape.
The page saysThe female lays four to seven eggs and incubates them while her partner stands guard
The source saysThe female lays a clutch of four to seven eggs, which she incubates while her partner stands guard.
The page saysMute swans feed mainly on aquatic plants, and also graze on grass in nearby fields
The source saysThey feed mainly on aquatic plants, but also graze on grass in nearby fields and meadows.
The page saysNo. A feeding swan often makes quiet grunts, and a disturbed one hisses loudly, most of all near its cygnets. The wings are noisy too: you might hear a swan flying over before you see it.
The source saysThey often grunt softly while feeding and will hiss loudly if disturbed – especially when protecting their young. While flying, their wings make a dramatic whooshing sound, so you might hear them coming before you see them!
The page saysMales and females form strong pair bonds that often last for life, and a pair bows and entwines necks each spring.
The source saysEach spring, pairs perform a beautifully synchronised courtship display out on the water, bowing to each other with wings held aloft, before entwining their necks, often forming a heart shape.Note: vibe.reason, second part

Source
05

New York State Department of Environmental Conservation

Mute Swan. New York State Department of Environmental Conservation.

The page saysNot actually mute: it hisses, snorts and twirls with its wings raised.
The source saysmute swans, as indicated by their name, are not very vocal. However, they will grunt, snort, or hiss to communicate
The page saysNot actually mute: it hisses, snorts and twirls with its wings raised.
The source saysboth males raise their wings and fluff their feathers, known as "busking" (also part of the mating ritual), and begin twirling in place
The page saysRaises its wings and twirls in a busking display, part of both rival standoffs and the mating ritual
The source saysboth males raise their wings and fluff their feathers, known as "busking" (also part of the mating ritual), and begin twirling in place
The page saysWhen an adult male with a nest or brood meets another male, both raise their wings and fluff their feathers
The source sayswhen an adult male with a nest or brood encounters another male. In these instances both males raise their wings and fluff their feathers
The page saysThis is called busking, and the two males then twirl in place
The source saysknown as "busking" (also part of the mating ritual), and begin twirling in place
The page saysNew York's wildlife agency says the ritual appears more like a dance than a fight
The source saysa ritual that appears more like a dance than a fight
The page saysBusking is also part of the mating ritual
The source saysknown as "busking" (also part of the mating ritual)
The page saysBreeding mute swans are very territorial, and both sexes are aggressive toward people and other waterfowl within their nesting area
The source saysDuring the nesting and brood-rearing periods mute swans are very territorial. Both males and females are aggressive toward people and other waterfowl within their nesting area.
The page saysNew York's wildlife agency says they eat about 4 to 8 pounds (1.8 to 3.6 kg) of vegetation a day
The source saysconsume about 4-8 pounds of vegetation dailyNote: task #1114: figure tied to its New York source, metric added
The page saysNew York's wildlife agency says they were first brought to the United States from Europe in the late 1800s, and it lists the mute swan as a prohibited invasive species
The source saysMute swans are a non-native, invasive species first brought to this country from Europe in the late 1800s
The page saysit lists the mute swan as a prohibited invasive species
The source saysDEC recently adopted regulations listing mute swan as a "prohibited" invasive species

Source
06

Animal Diversity Web, University of Michigan

Cygnus olor (mute swan). Animal Diversity Web, University of Michigan.

The page saysLakes, rivers, canals and sheltered bays across Europe and Asia, introduced in North America
The source saysThey live in well-sheltered bays, open marshes, lakes, and ponds.
The page saysLakes, rivers, canals and sheltered bays across Europe and Asia, introduced in North America
The source saysMute swans breed in the British Isles, north central Europe and north central Asia.
The page saysLakes, rivers, canals and sheltered bays across Europe and Asia, introduced in North America
The source saysThey have been successfully introduced in North America
The page saysblows from their wings can be especially painful
The source saysBlows from their powerful wings can be especially painful.
The page saysthere are records of swans knocking boaters off jet skis
The source saysThere are records of them knocking boaters off of jet skis.
The page saysTheir voices do not carry far, and Animal Diversity Web ties that to a straight trachea, the windpipe
The source saysthe sounds are not far-reaching due to their straight trachea
The page saysAn adult measures 144 to 158 cm long, with a wingspan of 2 to 2.5 metres
The source saysMute swans are large birds, measuring 144 to 158 cm. The wingspan is 2 to 2.5 meters.
The page sayssome swans have been seen with as many as four mates
The source sayssome have been observed to have as many as four mates
The page saysThey breed in the British Isles, north central Europe and north central Asia
The source saysMute swans breed in the British Isles, north central Europe and north central Asia.
The page saysdangerLevel: Medium
The source saysBlows from their powerful wings can be especially painful.Note: task #1114: Medium: can injure, rarely seriously
The page saysdangerLevel: Medium
The source saysThere are records of them knocking boaters off of jet skis.

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.