Common eider pair

Bird of the Month August 2023: Common Eider

The common eider, or dunter in Shetland dialect, is one of our most recognisable duck species. Between the distinctive black and white plumage of the males and the unique wedge-shaped beak, they really don’t look like any other species. However, at this time of year, moulting males take on an altogether different appearance that can cause a bit of confusion. All the more reason to take a second look at this beautiful and much-loved duck.

The Dapper Dunter

For much of the year, male eiders are unmistakeable. Europe’s heaviest duck, they are large, black and white birds with a pale green nape and pinkish blush to the breast. A long, yellow and grey wedge-shaped beak gives them a sleek facial profile unlike any of our other ducks. Another distinguishing feature is their endearing display call, often described as like a Frankie Howerd impression. Females may not be as eye-catching as the males, but they are nevertheless beautiful in their own right. A subtle mix of brown and grey barring gives them a warm russet plumage. This acts as an extremely effective camouflage when on the nest. They have the same beak shape as the male although it is not as brightly coloured. Ducklings are a dark chocolate brown colour.

Male common eider
Male eiders are unmistakeable with their black and white plumage
Female eider
Females are a lovely mix of browns, greys and black barring, perfect camouflage on the nest

At this time of year, however, male common eiders can look quite strange, especially when seen at a distance out at sea. In August, ducks moult all of their flight feathers at the same time. As a result, they are flightless for about a month, which makes them vulnerable to predation. To help protect the usually brightly coloured males at this time, they moult into what is called eclipse plumage. This often resembles a species’ female plumage to make them much more subtle and less noticeable. Male eiders turn mostly brown, retaining only a few odd patches of white. Their yellow beaks turn pale grey. At a distance, this makes them look distinctly odd and they can even sometimes be mistaken for non-duck species such as great northern divers.

Eclipse male eider
These males are in eclipse plumage

The Seafarer

Eiders are a truly maritime species. Indeed, that Shetland name comes from their bobbing up and down motion while at sea. In the UK, they breed in coastal colonies from Northumberland and Cumbria north. In winter they range further afield, with birds turning up as far south as Cornwall. Globally, they breed on Alaskan, Canadian, Icelandic, Scandinavian and Siberian coasts. They often form large rafts on the sea in winter, with the males’ plumage and their habit of staying reasonably close to shore making them fairly easy to spot. In flight, despite their size, they can reach speeds of up to 50 miles per hour. Common eiders eat a range of shellfish including crabs and mussels. To catch these, they dive to depths of up to 20 metres. They swallow most of their food whole.

Common eider raft
Eiders often form large rafts in winter

During the breeding season, females usually return to the same colony each year. In common with most ducks, the males are not involved at all once the female has laid her eggs. Famously, female eiders pluck their own breast down to line the nest with. The down is extremely light but has incredible insulating properties, helping to keep the eggs warm as they incubate. Removing the down also exposes the female’s body warmth to the eggs. Although she won’t eat at all during the four-week incubation period, a female eider will leave the nest every day or so to drink. While she is gone, the down helps keep the eggs hidden as well as warm. Once the eggs hatch, the ducklings leave the nest with the female as soon as their feathers are dry. They head straight to the sea and often form large crèches with other females. This practice makes it easier to protect the ducklings from predators.

Common eider family
Eider ducklings head to the sea very soon after hatching

From St Cuthbert to Eiderdowns

Common eiders have long been associated with humans, partly due to that wonderfully soft eiderdown. In Northumberland, people often call them St Cuthbert’s duck, or Cuddy’s duck for short. This is down to their association with the 7th century Bishop of Lindisfarne who spent some years as a hermit on nearby Inner Farne island. The island had, and still has, a colony of eiders. St Cuthbert apparently prohibited any hunting or disturbance of the ducks, even when they nested right next to the alter in his small chapel. Some people even count this as the world’s first environmental protection legislation. In reality, this may all be myth as no contemporary accounts mention the ducks in connection with Cuthbert. It was only 500 years later that the stories appeared. Whatever the truth of the stories, though, the common eider remains important in Northumberland, and it is the county emblem bird.

Eider male
Common eiders are the Northumbrian county bird

Humans have been harvesting eiderdown, meanwhile, for at least 1,100 years, probably much longer. We long ago realised that the light, soft, warm down would make an excellent material for insulating clothes and bedding, as well as filling pillows. Unlike some down harvesting which cruelly live-plucks birds or uses feathers from birds killed for food, eiderdown harvesting is cruelty-free. Most harvesters only take down from nests once the ducklings have left for the sea. Harvested colonies are usually bigger than natural ones because birds choose to go where they are protected from predators during the breeding season. Some communities, such as the World Heritage Site of Lånan in Norway, even build little houses for the ducks to provide even more security, as well as constantly patrolling the area. Approximately 70% of the four tonnes or so of down harvested globally each year comes from Iceland. The remainder comes from Norway and Canada.

Eider female on the nest
Eider females use their own feathers to line the nest

Excellent Eiders

From their incredible down to their comical wooing calls, there is lots to love about the common eider. They can be incredibly tame at down-harvesting colonies, with humans sometimes able to lift nonchalant birds off the nest. Yet they are also incredibly hardy, able to survive winter at sea and dive to impressive depths for food. Definitely more than enough reason to look out for this impressive sea duck.

Listen out for the Frankie Howerdesque ooos at the end of this clip

Thanks for reading! If you like my writing and would like to leave me a tip, you can do so below.

Leave a Comment