When we think of ducks, our minds often go instantly to images of bright and bold males, while the females look a little drabber.
That’s certainly the case for many of our duck species along the Solent.
The reason for this change in colouration is linked to differing parental roles. Females spend more time incubating eggs and caring for the chicks, so their plumage tends to be duller and better camouflaged, helping them to blend into their surroundings and stay hidden from predators. The males, however, have a smaller role to play in raising the chicks, and so most of the effort is put into impressing females and keeping other males away. The brighter the feathers, the healthier and more suitable a particular male is to a female.
Photo of male and female mallard
Many species of diving and dabbling ducks have this difference – the only ducks in fact that do not stick to this rule are the shelduck family, which includes the common shelduck and the Egyptian goose (a non-native resident duck to the UK).
Shelduck male and females have the same plumage because they share parental care duties, meaning neither must show off more than the other.
Photo of two male shelduck accompanied by a female
The ducks you can spot most easily along the Solent belong to the dabbling duck family – which includes species like the mallard, gadwall, teal, wigeon, shoveler and pintail.
They are called dabbling ducks because of their feeding habits, finding food on the water’s surface or sifting the bottoms of ponds, rivers and lagoons with their backsides in the air.
In late August, you might notice something rather strange at your local duck pond. The brightly coloured male mallards seem to disappear, leaving only females behind. So where have they gone?
The answer is that they haven’t vanished at all. Instead, the male ducks are undergoing a remarkable change known as an eclipse plumage.
A vanishing act
Male ducks have their moment to shine during the winter and spring months, showing off impressive colours to attract females. However, at the end of the breeding season, they undergo a moult that temporarily transforms their appearance as old, worn feathers are replaced with new ones.
All birds replace their feathers at certain times of the year. Some do so gradually, moulting a few feathers at a time, while others undergo an extreme loss of feathers in one go. This is called a catastrophic moult. Shelducks are well known for this strategy, which you can read more about in our previous blog.
For around a month at the end of summer, dabbling ducks lose all their feathers, including their primary flight feathers that provide the power needed for flight, before growing healthy new ones.
You can see the challenge this creates for males. A duck sporting bright eye-catching plumage would be easier for predators to spot while it was grounded and unable to fly without its flight feathers.
This is where the crafty eclipse plumage comes into its own.
Photo of male mallard duck moulting
When flightless and vulnerable, males lose their colourful feathers and take on the drab plumage of females, helping them blend into their surroundings for several weeks until their flight feathers regrow.
Not only does it provide camouflage, but it can also confuse predators. Female ducks usually offset their moult for several weeks compared to males, making it difficult for predators to tell which birds are still able to fly and which are temporarily flightless. Rather than risk wasting energy on a bird that could easily escape, predators may avoid hunting them altogether.
Here are four ducks in their eclipse plumage that you might spot around the Solent in late summer:
Mallard
Normally, male mallard ducks have a fantastically vibrant metallic green head, accompanied by a grey and brown body. In eclipse plumage, however, they lose this entirely in favour of a mottled brown appearance.
The easiest way to tell males apart from females during this period is by looking at bill colour. Males retain their yellow bills, while females keep their dull, orange-coloured bills.
Males will also typically retain some chestnut colouring on the chest and a dark stripe running along the top of the head.
After three to four weeks in eclipse plumage, male mallards regrow their colourful feathers again, ready for the winter season.
Male mallard: bright green head, yellow bill, grey and brown back and black tail
Female mallard: mottled brown plumage with dull orange bill
Two male mallards in eclipse plumage: mottled brown colour with yellow bill and a dark head
Teal
Teals migrate to the Solent coastline for the colder months and, if you spot them shortly after they arrive from their journey across the Baltics, you might think the males look a little worse for wear.
This is often because they are coming out of their eclipse plumage phase. Male ducks regrow their flight feathers first before investing energy into regrowing their colourful feathers.
Once they arrive on the Solent and have had time to rest and feed within our rich coastal habitats, they can shift their energy from migration to growing their stunning breeding plumage once again.
Male teal are quite possibly one of the most beautiful duck species we get along our waters. With a chestnut head, vibrant teal eye stripe that changes colour in the light, grey-brown mottling and a bright yellow rear patch, what doesn’t this duck have?
Males emerging from eclipse plumage often still have remnants of their fabulous head pattern, and within a few weeks of arriving on the Solent these will be replaced by a winter-ready coat.
Male teal: a chestnut head, vibrant teal eye stripe, grey-brown mottling and a bright yellow rear patch
Female teal: mottled brown plumage, with teal patch on their wing, and a black bill
Male teal in eclipse plumage: mottled brown colour with a dark head, grey and teal wings, and dull bill
Shoveler
Another winter migrant to the Solent coast, this species of duck is fantastically named because of their large spoon-shaped bills, equipped with specialised lamellae that help them filter-feed in the water.
When they arrive at the end of summer, many of the males will have finished their moult – but at this stage they are still in the phase of growing their colourful feathers. So, you might notice shovelers also looking a bit drab and untidy during this time.
Male shovelers, during the winter and spring, have dark green heads with a bright yellow eye, white chests and orangey‑brown sides. Females are mottled brown, showing a glimpse of a pale blue forewing.
Males in eclipse plumage again look like females, and if you’re struggling to tell the difference then the rangers like to look out for differences in bill colour. Females tend to have a dull orange bill, whereas the males have a dark bill all year round. The males also have darker head feathers.
Male shoveler: a vibrant green head, black back, terricota and white chest, and a long black bill
Female shoveler: mottled brown plumage, with a long orange bill
Male shoveler in eclipse plumage: mottled brown colour with a dark head and long black bill
Goosander
At the beginning of the blog, we mentioned that many dabbling and diving ducks go through an eclipse plumage, and this last duck is a member of the latter.
Goosanders are a type of diving duck from the sawbill family. This is due to their bills being long, thin and covered in serrated edges, like a chainsaw.
There are a few spots around the Solent where you can see goosanders, as they prefer hiding away in harbours and along estuaries, just where the river meets the sea.
The males and females, during the winter and spring, look completely different and are easy to tell apart. But come the end of summer, the male goes through quite a stunning change, which can confuse a lot of birdwatchers.
During the male’s eclipse plumage, the only way you can tell the difference is by looking out for a large white patch on the wing. Otherwise, the brown head, dull white belly and grey body are identical to those of a female.
Once he’s gone through his moult, the male regrows a fabulous green head, with a prominent forehead, black back and white underbody.
Male goosander: a vibrant green head, black back and long red bill
Female goosander: brown head, white and grey back and a long, red bill
Male goosander in eclipse plumage: dull brown head, grey back with a prominent white wing stripe, and a long dull beak
Have you been tricked by a male in eclipse plumage? This fascinating disguise has fooled many a birdwatcher and will continue to do so at the end of summer every year.
If you enjoyed learning about some of the duck species we find on the Solent, check out our Meet the Birds pages to discover what other ducks and waterbirds can be found along the coast during the winter months.
