Saturday, 2 February 2013

Arctic Tern


order : Charadriiformes      Genus & Species : Laridae     Family : Sterna paradisaea

The Arctic tern’s streamlined form allows it to dive for fish with masterful agility and minimizes drag during its long migrations. Arctic tern Life is a long summer for the Arctic tern, but its globe-trotting migrations are hard work. Each annual round trip may involve crossing vast oceans and total up to 24,000 miles. They found in the far north of Canada, Asia and Europe; spends the rest of the year in the southern Pacific and Atlantic, chiefly on Antarctic pack ice. 

Habitat : The Arctic tern breeds within latitudes from Massachusetts and Brittany, France, north to within 420 miles of the North Pole, at sites such as the northern tip of Greenland. During the summer breeding season, long hours of sunlight give the bird plenty of time to catch food.The tern nests mainly on coasts or offshore islands, flying short distances out to sea to catch fish for itself, its mate and chicks. In Scandinavia and Canada, the Arctic tern sometimes follows rivers far inland, nesting up to 180 miles from the sea and feeding on fish in the lakes and rivers. After breeding and rearing its chicks, the Arctic tern spends the rest of the year at sea, flying a vast distance south to spend the southern summer (the northern winter) mainly around Antarctica. There, the tern rests on icebergs or floating pack ice. 
Food & Feeding : Fish, crustaceans and insects are the main food of the tern, but prey varies with location. Shrimp, crabs, migrating insects and small squid are taken in flight from the surface waters; the tern also snaps up flies and moths at its breeding grounds. The tern catches fish by diving into the sea, although it rarely dives deeper than 24" and may be under the waves for no longer than a second.The tern holds fish crosswise in its sharp-edged bill and can catch one or two more fish while still carrying the first. Herring, haddock, sprats, butterfish and even small salmon are typical prey, but sand eels are especially important at breeding time, providing a nutritious and convenient-sized meal for chicks. 
Behavior : Terns nest in noisy colonies (often several thousand pairs) and feed in flocks of ten to several hundred birds. It’s best known for epic journeys from northern breeding grounds to the southern oceans, returning the next year to breed. In its lifetime, an Arctic tern may travel at least 480,000 miles. The tern migrates alone or in small groups. It usually flies down the west coast of North America, then follows the east coast of South America or crosses the Atlantic before continuing south. Eurasian birds follow the Atlantic coasts of Europe and Africa. With wind directions, these routes are the quickest and easiest for terns. 
Breeding : Terns pair for life. When adults return to their old nest site in spring, they renew their bond with courtship flights.The male brings food to his mate to help her into peak breeding condition. The female lays one to three eggs in a scrape in sand or gravel. Both parents incubate the eggs and bring food to the young when they hatch in three weeks.Young stay in the nest for two or three days, then leave to hide in groundcover. They can fly in three to four more weeks, but parents may feed them for another two months. 

Bill : Sharp edges of the bill help the tern hold a wriggling fish.The deepred color stimulates the chicks to beg for food; after the breeding season, the bill turns black. 
Wings : Long and pointed to allow the tern to dive with speed and agility when surface feeding. 
Plumage : Adult is pure grayish-white with a black cap. In winter, only the back of the head is black with a black line through the eye. 
Feet : Three front toes are webbed, although the tern isn't a particularly good swimmer.The fourth toe is reduced to a peg at the back of the foot. 
Tail : Long tail streamers act like a rudder to help the tern adjust its angle of descent as it dives for fish.The streamers are also used for display in courtship flights. 

Weight : 3.5–4 oz. 
Length : 13-14"
Wingspan : 30-34"
Sexual Maturity : 2-5 years
Breeding Season : May–August 

The tern defends its nesting colony fiercely: it’ll swoop to attack predators or humans and may draw blood with its sharp bill.