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Site officiel. Fabrice Fortin hommes Holly Bleasdale femmes. Elisabete Ribeiro Ansel. Syrine Balti. Jean Galfione. Kevin Rans. Vanessa Boslak. Romain Mesnil. Laurens Looije. Roza Kasprzak. Damiel Dossevi. Caroline Boquet.
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A newborn calf is about 1. Like belugas, they have a small head, a stocky body and short, round flippers. Narwhals lack a dorsal fin on their backs, but they do have a dorsal ridge about 5 cm high that covers about half their backs. This ridge can be used by researchers to differentiate one narwhal from another. It is thought that the absence of dorsal fin actually helps the narwhal navigate among sea ice. Unlike other cetaceans —the order which comprises all whales—, narwhals have convex tail flukes, or tail fins.
These whales have a mottled black and white, grey or brownish back, but the rest of the body mainly its underside is white. Newborn narwhal calves are pale grey to light brownish, developing the adult darker colouring at about 4 years old. As they grow older, they will progressively become paler again.
Some may live up to years, but most probably live to be 60 years of age. Although the second, smaller incisor tooth often remains embedded in the skull, it rarely but on occasion develops into a second tusk. Tusks typically grow only on males, but a few females have also been observed with short tusks.
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The function of the tusk remains a mystery, but several hypotheses have been proposed. Many experts believe that it is a secondary sexual character, similar to deer antlers. Thus, the length of the tusk may indicate social rank through dominance hierarchies and assist in competition for access to females. Indeed, there are indications that the tusks are used by male narwhals for fighting each other or perhaps other species, like the beluga or killer whale. A high quantity of tubules and nerve endings in the pulp —the soft tissue inside teeth — of the tusk have at least one scientist thinking that it could be a highly sensitive sensory organ, able to detect subtle changes in temperature, salinity or pressure.
Narwhals have not been observed using their tusk to break sea ice, despite popular belief. Narwhals do occasionally break the tip of their tusk though which can never be repaired. This is more often seen in old animals and gives more evidence that the tusk might be used for sexual competition. Ptarmigans are hardy members of the grouse family that spend most of their lives on the ground at or above the treeline.
Like other grouse, ptarmigans have chunky bodies, short tails and legs, and short, rounded wings. All ptarmigans have feathered feet, unique among chickenlike birds, which improve their ability to walk in snow. They also have white wings throughout the year. Inflatable red combs above their eyes, which are especially evident in territorial and courting males, are inconspicuous to barely visible in females. Ptarmigans have three seasonal plumages per year, instead of the two that are usual for most birds. These plumages keep the birds, particularly the female, well camouflaged at all times.
In winter, all ptarmigans of both sexes are basically white. Whereas White-tailed Ptarmigans have permanently white tail feathers, the tails of Willow and Rock Ptarmigans remain black throughout the year. In winter, male—and some female—Rock Ptarmigans sport a black stripe that extends through the eye to the bill as if they had put on charcoal goggles to prevent snow blindness , distinguishing them from male Willow Ptarmigans.
In ptarmigans, the moult, or shedding of old feathers, starts with the head and progresses towards the tail. As soon as the spring snowmelt begins, females moult into a barred breeding plumage of brown, gold, and black. Female ptarmigans are difficult to tell apart in spring, but the overall tones of the White-tailed Ptarmigan females are cooler in comparison to those of the other two species. Breeding males delay their moult. Its name comes from the partial webs between its toes.
Males and females are identical in rather plain brown or grey plumage although females are slightly larger. The species can be difficult to distinguish from other small sandpipers.
Semipalmated Sandpipers moult, or shed, their body feathers twice a year. The change to the greyish-brown fall-winter plumage usually starts on the breeding grounds and is completed after arrival on the non-breeding area. The moult that takes place on the non-breeding area prior to spring migration gives them a slightly brighter more brown breeding plumage.
Adults moult their flight feathers wings and tail gradually—retaining the ability to fly at all times—and only once per year, usually in the non-breeding area. Some juveniles do not replace any flight feathers in their first winter, as these are quite new.
Others, however, moult some of the outermost primaries outer wing feathers , which are important for flight and wear most rapidly. Shorebirds form one of the most interesting, important, and spectacular groups of birds in Canada. They comprise a diverse group of species, including the plovers, oystercatchers, avocets, stilts, turnstones, sandpipers, yellowlegs, snipes, godwits, curlews, and phalaropes. To the uninitiated, many species of shorebirds, especially the smaller sandpipers, appear confusingly similar, representing variations on a design involving long legs, a long bill, sharp, dynamic wings, and a streamlined body.
These design features all reflect the lifestyle for which the birds are adapted—long legs for wading in water or on mudflats or marshes, the long bill for searching for tiny animal and insect prey by probing into Arctic tundra or a variety of substrates, and long wings and a streamlined body for swift flight over long distances. The Redhead Aythya americana is a well-known and widely distributed North American diving duck. The adult male is a large, grey-backed, white-breasted duck with a reddish-chestnut head and black neck and chest. It resembles the larger male Canvasback.
The adult female is a large, brown-backed, white-breasted duck with a brown head, whitish chin, abrupt forehead, short, broad bill, and pearl-grey wing patches. Female Redheads, although larger, may be confused with female Ring-necked Ducks and scaups. In autumn young Redheads resemble adult females, although their breast plumage is dull grey-brown, rather than white. During November and December, the young begin to develop the adult plumage, which has almost completely grown in by February. The genus Aythya, to which the Redhead belongs, includes 12 species, all of which are well adapted to diving.
The body is rounded and thick with large feet, legs set back on the body, and a broad bill. Body shapes vary from the big, long-necked, long-billed Canvasback to the short-billed scaup. Of the species of woodpeckers worldwide, 13 are found in Canada. The smallest and perhaps most familiar species in Canada is the Downy Woodpecker Picoides pubescens. It is also the most common woodpecker in eastern North America.
This woodpecker is black and white with a broad white stripe down the back from the shoulders to the rump. The crown of the head is black; the cheeks and neck are adorned with black and white lines.
Male and female Downy Woodpeckers are about the same size, weighing from 21 to 28 g. The male has a small scarlet patch, like a red pompom, at the back of the crown. The Downy Woodpecker looks much like the larger Hairy Woodpecker Picoides villosus , but there are some differences between them. The Downy is about 6 cm smaller than the Hairy, measuring only 15 to 18 cm from the tip of its bill to the tip of its tail.
Woodpeckers are a family of birds sharing several characteristics that separate them from other avian families. Most of the special features of their anatomy are associated with the ability to dig holes in wood. The straight, chisel-shaped bill is formed of strong bone overlaid with a hard covering and is quite broad at the nostrils in order to spread the force of pecking.
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A covering of feathers over the nostrils keeps out pieces of wood and wood powder. The pelvic bones are wide, allowing for attachment of muscles strong enough to move and hold the tail, which is important for climbing. Another special anatomical trait of woodpeckers is the long, barbed tongue that searches crevices and cracks for food. The salivary glands produce a sticky, glue-like substance that coats the tongue and, along with the barbs, makes the tongue an efficient device for capturing insects. Signs and sounds.
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As early as February or March a Downy Woodpecker pair indicate that they are occupying their nesting site by flying around it and by drumming short, fast tattoos with their bills on dry twigs or other resonant objects scattered about the territory. The drumming serves as a means of communication between the members of the pair as well. Downys also have a variety of calls. They utter a tick, tchick, tcherrick , and both the male and the female add a sharp whinnying call during the nesting season.
Hatchlings give a low, rhythmic pip note, which seems to indicate contentment. When a parent enters the nest cavity, the nestlings utter a rasping begging call, which becomes stronger and longer as the chicks mature. Adult coho salmon have silvery sides and metallic blue backs with irregular black spots.