Whooper swans

Birds of the Month December 2023: Bewick’s and Whooper Swans

Here in the UK, our only fully resident swan species, the mute swan, is joined in winter by two northern relatives. Bewick’s and whooper swans both breed further north but travel here in varying numbers each autumn. Superficially very similar to each other, these two swans have a number of differences in both their appearances and breeding and wintering grounds. Bewick’s swans are actually a subspecies of the North American tundra swan, although in the past they were considered a full species. Whatever their taxonomic status, though, December is a wonderful month to try and catch up with both Bewick’s and whooper swans.

Spot the Difference

Most of the world’s six swan species, bar Australia’s black swan, conform to the classic, largely white plumaged swan colouration. This includes Bewick’s and whooper swans. In fact, whooper swans are considered such ‘typical’ swans that their scientific name, Cygnus cygnus, reflects this. When a bird or animal has the same genus and species name, it is called a tautonym. This usually signifies that the creature in question is the most typical representative of the genus. This is the type species.

Whooper and mute swan
Whooper swans have a large area of yellow on the bill, unlike the mute swan in this picture

Both Bewick’s and whooper swans have black legs and feet. They sport yellow and black bills. The easiest way to tell the two birds apart is by the extent of yellow on these beaks. In whooper swans, the yellow forms a triangle that extends down past the nostrils on each side. Bewick’s bills, meanwhile, show a greater proportion of black. The yellow patch is also a more rounded shape that doesn’t reach the nostrils.

Bewick's swans
These Bewick’s swans have less yellow and more black on their bills than whoopers

Another way to separate the two is on size. Whooper swans are similar in size to mute swans. As such, they are one of the world’s heaviest flying bird species. The smaller Bewick’s swan is more comparable in size to Canada geese. Bewick’s also have a more rounded head and smaller beak compared to the whooper’s wedge-shaped head and long bill. Youngsters of both species begin life as fluffy grey cygnets, looking similar to mute swan babies. By winter, these cygnets will be a grey or buff colour. Their beaks, meanwhile, are pale pink and black and show no yellow. Both species are much more vocal than mute swans. Whooper swans have a louder, more bugling call compared to the softer ‘hoo-hoo’ of Bewick’s.

Whooper swan juvenile
By winter, both whooper and Bewick’s juveniles sport pinkish and black beaks and a buff plumage like this whooper youngster

Beaky Fingerprints

Incredibly, those yellow and black beak markings mentioned earlier are subtly different from bird to bird. This means they are as individual as fingerprints, although the differences are more noticeable in Bewick’s swans than in whoopers. In 1963, conservationist and founder of the Wildfowl and Wetlands Trust, Peter Scott, first noticed the differences in the beaks of Bewick’s swans visiting Slimbridge. He and his family lived at the site and enjoyed painting the birds, and it was this practice that led them to look more closely at their subjects. Spotting these beak differences prompted Scott and his family to name each swan and follow their behaviour every winter. As the years passed, they created beautiful painted catalogues of the birds’ beaks.

Bewick's beaks Slimbridge
This beautiful catalogue of Bewick’s swan beaks is on display at Slimbridge – original painting copyright of WWT

By referring to this catalogue, they could record each individual bird’s annual arrival and departure in autumn and spring. Recognising each bird also revealed that they mated for life and that families stayed together during the winter. Researchers today continue the study in what is probably the only long-term project using facial recognition rather than ringing to recognise particular birds. In more general terms, the beak patterns divide into three broad types for both Bewick’s and whooper swans. ‘Dark neb’ beaks show a thick, black line that connects the bill tip to the brow line and divides the yellow areas. This form is rare in whooper swans. ‘Yellow neb’ bills have no continuous black line from tip to brow dividing the yellow. The last group, ‘penny face’, shows the black dividing line but with an open, yellow area in the middle of the line.

Bewick's swan yellow neb
This yellow neb Bewick’s swan has no black line between the bill tip and brow
Bewick's swan black neb
This black neb Bewick’s has a clear black section dividing the yellow bill areas

From Russia (and Iceland) With Love

Bewick’s swans breed across Arctic Russia on tundra pools and lakes. Eastern breeding birds winter in China, Korea and Japan. A small group winters on the southern shores of the Caspian Sea. More westerly breeding Bewick’s travel to various wintering grounds spread across the Netherlands, Denmark, Ireland and the UK. East Anglia, the Severn Estuary and Lancashire are regular wintering hotspots for the approximately 4,000 birds that come here.

Bewick’s swans are very vocal, unlike our resident mute swan

There has been a marked change in the number wintering here, however, with a drop of 95% over the last 25 years. Ireland and the Netherlands also see less birds. Although some of this is down to population declines, climate change is the main cause. As conditions stay warmer further north, Bewick’s swans can save valuable energy by wintering closer to their breeding grounds. This shortening of migration is called short-stopping. Warmer weather also means that those birds that do come here are arriving later than ever. Their subspecies partner, the whistling swan, breeds in Arctic Canada and Alaska.

Finnish one Euro coin
The whooper swan is Finland’s national bird and appears on their one euro coins

Whooper swans breed slightly further south than Bewick’s swans. They favour pools and lakes in scrubby taiga regions of Scandinavia and Russia, as well as breeding further south on the Asian steppe. There is also an Icelandic breeding population. In addition, between 25 and 30 pairs breed in northern Scotland each year, predominantly in Shetland, Orkney and the Outer Hebrides. British and Irish wintering birds come almost exclusively from the Icelandic population. They tend to winter in more northern parts of the UK and Ireland than their smaller relative.

Whooper swans in a field
In winter, whooper (and Bewick’s) swans often feed in fields during the day

Both, however, often spend winter daylight hours feeding in fields on grass, grain and the remains of beet or potato crops. They roost on lakes and water bodies at night for safety. In contrast to Bewick’s swans, there has been a 244% increase in the number of wintering whoopers in the UK since 1995, with around 20,000 birds now visiting. This growth is down to a huge increase in the Icelandic breeding population, although populations elsewhere aren’t doing as well.

Swans A-swimming

Bewick’s and whooper swans are two beautiful winter visitors to the UK. Although their fortunes are mixed, with less Bewick’s travelling to our shores and more whoopers, both face a number of threats. Lead shot and fishing weight ingestion, collision with power lines, habitat loss and illegal hunting, despite global protections, all impact their numbers. Climate change is also likely to increasingly effect both species on their breeding grounds as weather patterns and food supply become more unpredictable. At the very least, the small number of Scottish breeding whooper swans may start to find our shores too warm for them. And there may come a time when short-stopping Bewick’s swans choose not to visit the UK at all. So, while we can still enjoy them, why not get out and try to spot one or both of these swans a-swimming this December?

Wintering whooper swans
Wintering whooper swans

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