By Dominic Couzens
Whatever you have learnt about ducks probably isn’t true about the Goosander. This is a very different animal from your quacking park staples, and almost everything they do, it doesn’t do.
If you take a list of unusual duck facts, many of them will be true of Goosanders. The Goosander is a duck apart, a thoroughbred and a maverick. Far from being a portly, bread-ivorous consumer of benefit handouts, the Goosander is
a big-game fishing duck.
Instead of occupying slummy waters in the urban sprawl, this bird is at home in fast-flowing, highly oxygenated, supercharged wild rivers and deep pools. It lives, in many parts of its range, among forests full of bears and wolves. It is the antithesis of the duck that is, if not domesticated, then domiciled. It is wild and untamed.
My first experiences with these characters always led me to assume that people, in the view of Goosanders, were to be avoided. From deep reservoirs in winter to streams in summer, you tended to see the back end before you saw the front, the big, torpedo-shaped bodies whistling off and away, not a thought for pleasantries. There is no breaking bread with a Goosander.
Their diet, too, is the opposite of a handout. Many species of ducks, throughout the world, take an extremely leisurely approach to feeding. Mallards, for all their adaptability, give the impression that they are never making any more effort than we would to dig up carrots. Shovelers bulldoze the water surface, Teals pick seeds from the mud; Pochards graze underwater and sleep for much of the rest of the time; even Eiders in the sea only dive down to yank immotile cockles from the sea bed.
Goosanders, though, are birds that chase, and their prey is both fast and reluctant to be caught. They are among the very few ducks that catch fish for a living, along with their ‘sawbill’ relatives, the Red-breasted Merganser and Smew. These ducks need pace underwater, and they need unobstructed space in which to spot and snatch their prey.
Almost any fish species less than 20cm in girth may be consumed, anything from a stickleback to a salmon. They catch what is most abundant; in extreme cases they can swallow a fish 36cm long. They will search among the sediment and among stones, in a submarine world it is hard for us to imagine. They have excellent vision and will hunt well into dusk, or even after dark.
The serrated edges of their mandibles allow them to hold slippery prey.
Goosander: Hunting and homes
Where fishing is good, Goosanders will gather. In contrast to the quarrelling Mallards spitting over bread, these sleek hunters will hunt co-operatively, and with deadly effectiveness. Sometimes they dive as one to startle fish into rash decisions, and sometimes they will form a line to drive shoals of prey into shallow water. There is no jostling in this classy species.
Goosanders don’t follow the duck trail in much of their breeding behaviour, either. Despite being large, they nest in holes in trees, or sometimes rocks or strange sites, such as hollow logs on the ground, or in buildings.
These holes may be anything from 1m above ground to an impressive, decidedly lofty 30m. True, that epitome of duck-hood, the Mallard, will sometimes nest in tree-holes as well, but among duck species as a whole it remains unusual. Most types, from Tufted Ducks to Gadwalls, nest among vegetation on the ground.
One might immediately sense a problem for Goosanders, when looking for nest-sites: where can they find anywhere big enough? You could fit a Mandarin or a Smew into a small space, but not a Goosander. The penthouse suite must be spacious. Fortunately, in most parts of their range, Goosanders can call in large woodpeckers to provide housing.
In Europe, it is Black Woodpeckers and in North America, Pileated Woodpeckers, both of which are impressively bulky, and the woodpeckers’ habit of continuously excavating holes means that the ducks can keep their numbers up.
In Britain, where Black Woodpeckers are absent, Goosanders can use other holes and hollows, perhaps where branches have broken off. They will also use nest-boxes.
Almost all duck species’ progeny are quickly led to water almost as soon as they hatch. Nestling Goosanders spend their first day or two in the hole and then conform to type.
Of course, this arrangement comes with a snag, if you are 30m above ground. The chicks might be lightweights, physically, but they certainly aren’t in courage; necessity urges them to make the jump to ground, and then the mother urges them on, during the walk to water, however far that might be – 1.5km has been recorded.
It is quite a jolting start in life. In their early days, the mother may treat the chicks to a parental quirk which is unusual among wildfowl, a ride on her back. Presumably this has some survival value, but she isn’t always able to accommodate the whole brood, which can number 12, and occasionally as much as 17.
Goosander mystery solved
Looking at the Goosander’s overall behaviour, it seems to follow almost every unusual lead in the world of wildfowl, from hole nesting to ferrying young to chivvying fish.
Yet another strange behaviour that it exhibits might qualify as the strangest of all, and it is taking place at about the time you are reading this article, or just after.
You are probably aware that some birds perform special migratory movements for the purposes of moult. The most famous of these birds is the Shelduck, which flies from Britain to Germany in the summer, while Barnacle Geese sometimes fly north of the breeding grounds to moult. They go for no other reason than to change their feathers in a safe environment.
It has been discovered quite recently that Goosanders also have a moult migration, yet extraordinarily, it is confined to the males. For many years, it had been noted that the drakes were absent from their Scottish rivers from June to October or so, even where the mothers and broods were feeding, and for many years their whereabouts was a mystery.
It has now been shown that these drakes undertake a remarkable journey, travelling all the way to the North Cape of Norway. Here they mingle with 35,000 other males from other parts of western Europe and loaf about, moulting their plumage.
It is well known that ducks commonly show differential migration, with each gender exhibiting a different migratory strategy – for example
male Smews remain close to the breeding grounds in winter, while in Britain, further away, we see more females and immature males.
However, for the male Goosanders to migrate such a significant distance, leaving the females behind, is of a different order of magnitude.
On the other hand, for such a remarkable, unconventional duck, it is just another example of doing everything in its own way.
Scientific name: Mergus merganser
UK numbers: 3,100-3,800 breeding pairs /
12,000 wintering birds
Habitat: Upland rivers in summer, lakes, gravel pits and reservoirs in winter