---
title: "What the sources say about the Black Swan | AnimalTracks.wiki"
description: "55 claims from the Black Swan profile, each beside the words of the source that backs it."
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# What the sources say about the Black Swan (*Cygnus atratus*)

> 55 claims from the Black Swan profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Black Swan](https://animaltracks.wiki/animals/black-swan/)

## Cygnus atratus. The IUCN Red List of Threatened Species 2018: e.T22679843A131907524.

https://doi.org/10.2305/iucn.uk.2018-2.rlts.t22679843a131907524.en

| The page says | The source says |
| :--- | :--- |
| Least Concern | IUCN Red List category: Least Concern (LC). |

## Black swan | Kakīānau. New Zealand Birds Online.

https://www.nzbirdsonline.org.nz/species/black-swan

| The page says | The source says |
| :--- | :--- |
| A crinkle-feathered wing display | The larger male raises its elaborately crinkled upper wing feathers (coverts and tertials) in sexual and threat displays. |
| a bright red bill with a white band near the tip | The bill is a bright red with a terminal white band (note: "near the tip" also fits the Australian Museum's "a distinct narrow white band towards the end") |
| flight feathers that flash pure white when the wings lift or the bird takes flight | When the wings are lifted, or when flying, pure white flight feathers are visible |
| Adults measure 110 to 140 cm long | Length: 110 - 140 cm |
| Males typically weigh 5 to 7 kg, and females are markedly smaller, at 4 to 6 kg | Weight: 5 - 7 kg (male), 4 - 6 kg (female) ... Females are markedly smaller than males |
| In New Zealand, where black swans were introduced in the 1860s | Black swans were deliberately introduced, initially from Melbourne, in the 1860s. |
| the oldest known bird lived to 15 years | Maximum longevity 15 years - mean adult survival 0.84 (note: New Zealand Birds Online (Williams 2013, updated 2023), scoped to New Zealand in the sentence; ADW's 2004 'forty years in the wild' figure was not used) |
| When submerged plants are sparse or out of reach, they will graze lakeside pastures | When lakes levels are high and submerged plants unreachable, or when submerged plants are sparse, swans will graze lakeside pastures |
| The larger male raises the elaborately crinkled feathers on his upper wings, called coverts and tertials, in courtship and threat displays. | The larger male raises its elaborately crinkled upper wing feathers (coverts and tertials) in sexual and threat displays. (note: "courtship" for the source's "sexual") |
| Black swans also hiss when defending their young. | Hisses when defending young or when threatening. |
| share incubation, which lasts 36 days on average | Incubation behaviour shared Incubation length (mean) 36 days |
| The larger male raises the elaborately crinkled feathers on his upper wings, called coverts and tertials, in courtship and threat displays. | The larger male raises its elaborately crinkled upper wing feathers (coverts and tertials) in sexual and threat displays. (note: FAQ 2) |

## Black Swan. Australian Museum, 2024.

https://australian.museum/learn/animals/birds/black-swan/

| The page says | The source says |
| :--- | :--- |
| Submerged water plants and algae, reached by plunging its neck up to a metre underwater; occasionally grazes on land | The Black Swan is a vegetarian. Food consists of algae and weeds, which the bird obtains by plunging its long neck into water up to 1 m deep. Occasionally birds will graze on land, but they are clumsy walkers. |
| Freshwater lakes, brackish estuaries, and coastal wetlands across Australia | Black Swans prefer larger salt, brackish or fresh waterways and permanent wetlands (note: unchanged stats.habitat, rechecked against sources) |
| a body that is mostly black | In adult Black Swans the body is mostly black |
| Black swans are vegetarians. | The Black Swan is a vegetarian. |
| They feed on algae and submerged water plants, reaching them by plunging their long neck into water up to a metre deep | Food consists of algae and weeds, which the bird obtains by plunging its long neck into water up to 1 m deep. (note: "submerged water plants" for "weeds": NZBO, "entirely herbivorous, preferring submerged freshwater plants") |
| though they are clumsy walkers | they are clumsy walkers |
| They are found throughout Australia except the Cape York Peninsula, and are more common in the south | Black Swans are found throughout Australia with the exception of Cape York Peninsula, and are more common in the south. |
| They are now common in New Zealand, and rarely reach New Guinea | The Black Swan has been introduced into several countries, including New Zealand, where it is now common, and is a vagrant to New Guinea. (note: "rarely reach" for the source's "vagrant") |
| Taking off needs at least 40 metres of open water | requiring 40 m or more of clear water to take off |
| Pairs stay together for life | They pair for life, with both adults raising one brood per season. |
| A clutch can hold up to ten eggs. | Clutch size: Up to 10 (note: Australian Museum (2024) over NZBO's table (clutch max 7), whose text also reports 7-14 egg clutches from dumped nests) |

## Black Swan. BirdLife Australia.

https://birdlife.org.au/bird-profile/black-swan/

| The page says | The source says |
| :--- | :--- |
| They can turn up wherever there is a wetland, from river estuaries, bays and large lakes to flooded pasture | They can occur wherever there is a wetland, from river estuaries, bays and great lakes to inundated pasture and water-meadows. (note: "flooded" for the source's "inundated") |
| Where wetlands dry out for part of the year, they disperse over wide distances looking for water | where the wetlands dry out for part of the year, swans are forced to disperse over wide distances in search of suitable water |
| When a wetland dries out for part of the year, black swans are forced to disperse over wide distances in search of suitable water, and have even been recorded swimming on isolated waterholes surrounded by vast tracts of arid, stony desert. | where the wetlands dry out for part of the year, swans are forced to disperse over wide distances in search of suitable water, and have even been recorded swimming in isolated waterholes surrounded by vast tracts of arid stony desert (note: FAQ 1) |

## Cygnus atratus (black swan). Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Cygnus_atratus/

| The page says | The source says |
| :--- | :--- |
| backed by loud, warning wing-beats | the wings of black swans make a louder sound than mute swans |
| a wingspan that can stretch to 200 cm | The wingspan ranges between 160 to 200 cm. |
| Their threats come with noise: a black swan's wingbeats are louder than a mute swan's | The threatening behavior of black swans is similar to mute swans; they both flap and wave their wings with two or three strokes followed by a call. However, the wings of black swans make a louder sound than mute swans. |
| it faces predators with its neck held erect and its bill pointed down | black swans flap their wings which produce loud noises and threaten predators with their necks erect and bills pointed down |

## Karawita et al. (2023). The swan genome and transcriptome, it is not all black and white. Genome Biology.

https://doi.org/10.1186/s13059-022-02838-0

| The page says | The source says |
| :--- | :--- |
| whose black plumage is linked to a pigment gene | We also implicate genetic differences in SLC45A2 gene in the iconic plumage of the black swan (note: tagline) |
| that is cut short in the white mute swan | We observed that SLC45A2 in the mute swan had a nucleotide deletion in the open reading frame instigating a frame-shift mutation and an in-frame early stop codon (note: tagline; "cut short" for the source's "early stop codon") |
| A 2023 genome study of black and mute swans | Here, we generate the first chromosome-length black and mute swan genomes (note: "2023" is the paper's publication year (reference metadata; the source text carries "© The Author(s) 2023")) |
| checked genes linked to feather colour in other birds | Genomic analysis of genes known to be associated with plumage color in other birds |
| It found a deletion in the mute swan's copy of SLC45A2 | We observed that SLC45A2 in the mute swan had a nucleotide deletion in the open reading frame instigating a frame-shift mutation and an in-frame early stop codon |
| a gene involved in making the pigment melanin | SLC45A2 encodes a transporter protein involved in melanin synthesis |
| that the black swan's copy lacks | Position of the frame-shift mutation in the mute swan SLC45A2 compared to the black swan genome |
| The deletion scrambles the gene's code and cuts it short, and may have stopped the gene working. | identified a potential frame-shift mutation in the first exon of SLC45A2 in the mute swan, which may have led to pseudogenization of this gene (note: "scrambles the code and cuts it short" for frame-shift plus early stop codon; "stopped the gene working" for pseudogenization) |
| The authors suggest it is a candidate change that could explain white feathers in white swans. | These results suggest that this deletion in SLC45A2 is a candidate genetic change that could be responsible for the white plumage in white swans |
| Black may once have been the normal swan colour. | Instead, it would appear that at one point in history black plumage for the swan was the norm rather than the exception. (note: blockquote lead-in, hedged with 'may' for the source's 'would appear') |
| If this mutation is what gave the two species their different colours, the authors write, it would suggest their last common ancestor was black. | should a mutation of SLC45A2 have resulted in the differential plumage of the black and mute swan, it would suggest that the last common ancestor of these birds was, in fact, black (note: blockquote) |
| The 2023 study also describes earlier infection experiments: unlike mallards and mute swans, black swans are extremely sensitive to highly pathogenic avian influenza, a severe form of bird flu, and die within two to three days of infection. | © The Author(s) 2023 ... Unlike mallard ducks and mute swans, the black swan is extremely sensitive to HPAI, succumbing to the disease within 2 to 3 days post-infection. ... These experimental studies are consistent with reports of natural infections (note: the paper reports this from earlier experiments it cites ([2, 3]), not its own; "2023" is the publication year) |
| The researchers' own genome work showed that, unlike other wild waterfowl, black swans lack an expanded set of immune genes and mount a poorly controlled inflammatory response to the virus. | We use these genomes and transcriptomes to show that unlike other wild waterfowl, black swans lack an expanded immune gene repertoire, lack a key viral pattern-recognition receptor in endothelial cells and mount a poorly controlled inflammatory response to highly pathogenic avian influenza. |
| A 2023 genome study found that the mute swan's copy of SLC45A2 | We observed that SLC45A2 in the mute swan had a nucleotide deletion in the open reading frame instigating a frame-shift mutation and an in-frame early stop codon (note: FAQ 3; "2023" is the publication year (reference metadata; "© The Author(s) 2023" in the source text)) |
| a gene involved in making the pigment melanin | SLC45A2 encodes a transporter protein involved in melanin synthesis (note: FAQ 3) |
| has a deletion that the black swan's copy lacks | Position of the frame-shift mutation in the mute swan SLC45A2 compared to the black swan genome (note: FAQ 3) |
| The authors suggest it is a candidate change that could explain white feathers in white swans. | These results suggest that this deletion in SLC45A2 is a candidate genetic change that could be responsible for the white plumage in white swans (note: FAQ 3) |
| If it is what gave the two species different colours, they write, that would suggest their last common ancestor was black. | should a mutation of SLC45A2 have resulted in the differential plumage of the black and mute swan, it would suggest that the last common ancestor of these birds was, in fact, black (note: FAQ 3; the source's own condition and hedge kept) |

## van Dongen et al. (2015). Variation at the DRD4 locus is associated with wariness and local site selection in urban black swans. BMC Evolutionary Biology.

https://doi.org/10.1186/s12862-015-0533-8

| The page says | The source says |
| :--- | :--- |
| How wary a swan is may be partly down to its genes. | Our results suggest that wariness in swans is partly genetically-determined |
| A study of black swans at two wetlands in Victoria, Australia | Field work was conducted at two wetlands in Victoria, Australia |
| linked a gene called DRD4 to how wary each bird was of people | non-urban swans initiated escape from humans earlier than urban swans. We found no inter-individual variation in the SERT gene, but identified five DRD4 genotypes and an association between DRD4 genotype and wariness |
| At a restricted-access wastewater site in a non-urban area | the Western Treatment Plant, Werribee (WTP; 37°54’S, 144° 40’E), a restricted-access wastewater processing site in a non-urban environment |
| swans fled an approaching person at a mean distance of about 96 metres, against about 13 metres | the mean flight initiation distance was 13 ± 0.4 m at the urban site and 96 ± 15.9 m at the non-urban site (note: "fled" for flight initiation distance, the distance at which a swan initiated escape from an approaching human; scoped to the two study sites) |
| at an urban park lake with around 5 million visitors a year | Albert Park Lake (APL; 37°50’S, 144° 58’E), an urban recreational park, which receives around 5 million visitors per annum |