Mergus is the genus of the typical mergansers, fish-eating ducks in the seaduck subfamily (Merginae). The Hooded Merganser, often termed Mergus cucullatus, is not of this genus but closely related. The other “aberrant” merganser, the Smew (Mergellus albellus), is phylogenetically closer to goldeneyes (Bucephala). Although they are seaducks, most of the mergansers prefer riverine habitats, with only the Red-breasted Merganser being common at sea. These large fish-eaters typically have black-and-white, brown and/or green hues in their plumage, and most have shomewhat shaggy crests. All have serrated edges to their long and thin bills that help them grip their prey. Along with the Smew and Hooded Merganser, they are therefore often known as “sawbills”. The goldeneyes, on the other hand, feed mainly on mollusks, and therefore have a more typical duck-bill. They are also classified as “divers” because they go completely under-water in looking for food. In other traits, however, the genera Mergus, Lophodytes, Mergellus, and Bucephala are very similar; uniquely among all Anseriformes, they do not have notches at the hind margin of their sternum, but holes surrounded by bone.
Red-breasted Mergansers are typically found in small flocks, rather than huge rafts. They forage by diving and swimming under water, sometimes in cooperative groups, working schools of fish into shallow water.
Listen to the sound of Red-breasted Merganser
Copyright remark: Most sounds derived from xeno-canto
|wingspan min.:||67||cm||wingspan max.:||82||cm|
|size min.:||52||cm||size max.:||58||cm|
|incubation min.:||31||days||incubation max.:||32||days|
|fledging min.:||60||days||fledging max.:||32||days|
Video Red-breasted Merganser
Mergus serrator is a widespread breeder across much of northern Europe, which
accounts for less than a quarter of its global breeding range. Its European breeding
population is relatively small (<120,000 pairs), but was stable between 1970-1990. Although the species declined in Norway, Sweden and Russia during 1990-2000, it was stable across much of its European range, and the large Finnish population increased markedly. The species probably underwent only a small decline overall.
This duck inhabits boreal regions – locally also temperate and arctic regions – in North America and Eurasia, from the British Isles to the Bering Street. The birds visiting the European Union belong to a population which breeding area extends from eastern Greenland to Novaya Zemlaya and includes the British Isles, Denmark and Scandinavia. The sub-population of Greenland, Iceland and the British Isles is partly sedentary, partly migratory and wintering in the British Isles. It amounts to about 15000-25000 individuals. The sub-population of northern continental Europe is wintering from the Baltic Sea to Portugal. it amounts to about 125000 individuals. Apart from some extension of its breeding area in the British Isles, this species seems to be quite stable. The birds visiting Greece belong most probably to a more eastern population, the winter quarters of which are centred on the Black Sea. This populations is estimated at 50000 individuals, but its trends are unknown.
males leave nesting areas early June, and, with immatures, moult in small coastal or near-coastal groups, sometimes at considerable distances from breeding places, reaching peak numbers mid-July. Autumn migration may begin September, but final departures from most northern breeding areas not until mid- or late October when peak movement through Baltic and to Black Sea region. As with other diving ducks, tendency for females and young to move earlier and further than males. Spring return may begin late February; arrives April in Baltic breeding range, later (dependent on thaw) further north and east.