Red-breasted Merganser (Diving and Sea Duck)

Red Breasted Mergansers
The red-breasted merganser (Mergus serrator) is a diving duck, one of the sawbills. [36]
 
The adult red-breasted merganser is 51–62 cm (20–24 in) long with a 70–86 cm (28–34 in) wingspan. 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 greyish body. The juvenile is like the female, but lacks the white collar and has a smaller white wing patch. [36]
 
Red-breasted mergansers dive and swim underwater. They mainly eat small fish, but also aquatic insects, crustaceans, and frogs. [36]
 
Its breeding habitat is freshwater lakes and rivers 
across northern North America, Greenland, Europe, and Asia. It nests in sheltered locations on the ground near water. It is migratory and many northern breeders winter in coastal waters further south. [36]
 

Common Merganser (Diving and Sea Duck)

Common Merganser
The common merganser (North American) or goosander (Eurasian) (Mergus merganser) is a large duck of rivers and lakes in forested areas of Europe, northern and central Asia, and North America. It eats fish and nests in holes in trees. [35]

It is 58–72 cm (23–28 in) long with a 78–97 cm (31–38 in) wingspan and a weight of 0.9–2.1 kg (2.0–4.6 lb); males average slightly larger than females but with some overlap. Like other species in thegenus Mergus, it has a crest of longer head feathers, but these usually lie smoothly rounded behind the head, not normally forming an erect crest. Adult males in breeding plumage are easily distinguished, the body white with a variable salmon-pink tinge, the head black with an iridescent green gloss, the rump and tail grey, and the wings largely white on the inner half, black on the outer half. Females, and males in "eclipse" (non-breeding plumage, July to October) are largely grey, with a reddish-brown head, white chin, and white secondary feathers on the wing. Juveniles (both sexes) are similar to adult females but also show a short black-edged white stripe between the eye and bill. The bill and legs are red to brownish-red, brightest on adult males, dullest on juveniles. [35]

Like the other mergansers, these fish-feeding ducks have serrated edges to their bills to help them grip their prey, so they are often known as "sawbills". In addition to fish, they take a wide range of other aquatic prey, such as molluscs, crustaceans, worms, insect larvae, and amphibians; more rarely, small mammals and birds may be taken. As in other birds with the character, the salmon-pink tinge shown variably by males is probably diet-related, obtained from thecarotenoid pigments present in some crustaceans and fish. When not diving for food, they are usually seen swimming on the water surface, or resting on rocks in midstream or hidden among riverbank vegetation, or (in winter) on the edge of floating ice. [35]

 

In most places, the common merganser is as much a frequenter of salt water as fresh water. In larger streams and rivers, they float down with the stream for a few miles, and either fly back again or more commonly fish their way

back, diving incessantly the whole way. In smaller streams, they are present in pairs or smaller groups, and they float down, twisting round and round in the rapids, or fishing vigorously in a deep pool near the foot of a waterfall

or rapid. When floating leisurely, they position themselves in water similar to ducks, but they also swim deep in water like cormorants, especially when swimming upstream. They often sit on a rock in the middle of the water,

similar to cormorants, often half-opening their wings to the sun. To rise from water, they flap along the surface for many yards. Once they are airborne, the flight is strong and rapid. They often fish in a group forming a semicircle and driving the fish into shallow water, where they are captured easily. Their ordinary voice is a low, harsh croak, but during the breeding season, they (including the young) make a plaintive, soft whistle.

 

Generally, they are wary, and one or more birds stay on sentry duty to warn the flock of approaching danger. When disturbed, they often disgorge food before moving. Though they move clumsily on land, they resort to running when pressed, assuming a very upright position similar to penguins, and falling and stumbling frequently. [35]

 

Nesting is normally in a tree cavity, so it requires mature forest as its breeding habitat; they also readily use large nest boxes where provided, requiring an entrance hole 15 cm (5.9 in) in diameter. In places devoid of trees (like Central Asian mountains), they use holes in cliffs and steep, high banks, sometimes at considerable distances from the water. The female lays 6–17 (most often 8–12) white to yellowish eggs, and raises one brood in a season. The ducklings are taken by their mother in her bill to rivers or lakes immediately after hatching, where they feed on freshwater invertebrates and small fish fry, fledging when 60–70 days old. The young are sexually mature at the age of two years. [35]

 

Hooded Merganser (Diving and Sea Duck)

Hooded Merganser
The hooded merganser (Lophodytes cucullatus) is a species of small duck. It is the only extant species in the genus Lophodytes. The bird is striking in appearance; both sexes have crests that they can raise or lower, and the breeding plumage of the male is handsomely patterned and coloured. The hooded merganser has a sawbill but is not classified as a typical merganser. [34]

Hooded mergansers are the second smallest species of merganser, with only the smew of Europe and Asia being smaller, and it also is the only merganser whose native habitat is restricted to North America.  [34]

 

​​​The hooded merganser is a sexually dimorphic species. The adult female has a greyish-brown body, with a narrow white patch over the lower breast and belly. She has a light reddish-brown crest extending from the back of the head. During the nonbreeding season the male looks similar to the female, except that his eyes are yellow and the female's eyes are brown. [34]

 

In breeding plumage the dorsal areas and the head, neck and breast of the mature male are mainly black with white markings; there are large white patches on either side of the crest, and they are particularly conspicuous when he raises his crest during courtship. His lower flanks are a rich reddish-brown or chestnut in colour, and the breast and undersides are more or less white, extending into white stripes across the crop and breast.

 

In both genders there are narrower pencilled white stripes along the tertial wing feathers; when the bird is in repose, then if the tertial feather stripes are visible, they have the appearance of longitudinal white stripes along the bird's lower back. [34]

 

First-winter birds differ from adult females in appearance in that they have a grey-brown neck and upper parts; the upper parts of adult females are much darker — nearly black. Furthermore, the young birds have narrower white edges to their tertial feathers than adults do. Females of all ages are dark-eyed, whereas in males the eyes become pale during their firstwinter. [34]

 

For preference the hooded merganser lives on small bodies of water such as ponds and small estuaries where there is ample emergent aquatic vegetation, but it also inhabits larger wetlands, impoundments, flooded timber, and rivers. They prefer fresh water but do occur on brackish water bodies as well. [34]

 

The hooded merganser is a diving predator that largely hunts by sight while under water. Most studies report that its diet varies according to circumstances, usually being dominated by fishes (44-81%). In addition it feeds on aquatic insects (13-20% of its diet) and other aquatic invertebrates such as crabs and crayfish (22-50%) [34]

References

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