Smergo minore

Identificazione

The adult red-breasted merganser is 51–64 cm (20–25 in) long, has a wingspan of 66–74 cm (26–29 in), and weighs 800–1,350 g (28–48 oz).<p>It has a spiky crest and long thin red bill with serrated edges. The male has a dark head with a green sheen, a white neck with a rusty breast, a black back, and white underparts. Adult females have a rusty head and a grayish body. Juveniles look similar to females, but lack the white collar and have smaller white wing patches.<p>The range of the red-breasted merganser broadly overlaps with that of the similar and closely related common merganser. The two species can therefore occur in the same place at the same time, though the species often choose different habitats (only the red-breasted frequents saltwater). Breeding male plumages are fairly distinctive, but other plumages such as those born by females, immatures, and non-breeding males can make the two species hard to distinguish. The common merganser displays more contrast between the darker head and lighter breast and has a light chin patch not seen on the red-breasted.<p>During courtship, the female gives a rasping prrak prrak, while the male gives a catlike meow. In flight, the female makes a harsh gruk. At other times this species is largely silent.

Tassonomia

Nome scientifico

Mergus serrator

Autorità

Linnaeus, 1758

Ordine

Anseriformi

Famiglia

Anatidae

Genere

Mergus

Areale e habitat

Areale riproduttivo

NA, PAL : s Greenland, Iceland, n British Isles, Scandinavia to Sakhalin and Kamchatka pens., and Kuril and Commander is. (se Russia), s through n Kazakhstan and ne China; w Alaska mainland through mainland Canada from Arctic to n Great Lakes and e to Nova Scotia

Areale non riproduttivo

to coasts of s Europe (e North Atlantic), Black and Caspian seas; Japan, Korean Pen. and e China (w North Pacific); to wc Mexico (e North Pacific), Gulf Coast and Florida (w North Atlantic)

Migrazione

Complete migrants

Comportamento

Red-breasted mergansers dive and swim underwater. They mainly eat small fish, but also consume aquatic insects, worms, crustaceans, and amphibians.<p>Its breeding habitat is freshwater lakes and rivers across northern North America, Greenland, Europe, and the Palearctic. It nests in sheltered locations on the ground near water. It is migratory and many northern breeders winter in coastal waters further south. Outside of the breeding season, it forms flocks that can reach 100 individuals, though these flocks are smaller during spring migration than they are in autumn migration and in winter. <p>The fastest duck ever recorded was a red-breasted merganser that attained a top airspeed of 100 mph (160 km/h) while being pursued by an airplane. This eclipsed the previous speed record held by a canvasback clocked at 72 mph (116 km/h).

Conservazione

The red-breasted merganser is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies. The species is also considered a game bird under the Migratory Bird Treaty between the United States and Canada. This means that the species gets some protection, though hunting it is legal in North America in certain seasons and places determined by local hunting regulations. However, few hunters are interested in the species and relatively few birds are harvested.<p>The species is widespread and common enough to be categorized as least concern by the IUCN, though populations in some areas may be declining. Threats include habitat loss through wetland destruction, exposure to toxins such as pesticides and lead, and becoming bycatch of commercial fishing operations. Anglers and fish farmers have also persecuted the species, which they regard as a competitor, though the impact of this on the species' population is not known.

Tendenza della popolazione

stable