Saturday, 2 February 2013

Brown Skua


order : Charadriiformes      Genus & Species : Stercorariidae     Family : Catharacta skua lonnbergi

A fierce bird of prey of southern oceans, the brown skua is successful because it will feed on anything that’s available — from penguin eggs to fish and even human’s garbage. With a bold air, a cruel bill and powerful wings, the brown skua looks like what it is — a cunning predator and master of the Antarctic skies. They found in a ring all around Antarctica, breeding on sub-antarctic islands, along the northern part of the Antarctic Peninsula and south of New Zealand. 

Habitat : With the exception of the south polar skua, the brown skua occurs farther south than any other flying bird. It breeds on subantarctic islands, in the South Shetland Islands and the northern part of Antarctica. The skua is found close to penguin colonies, where it gets most of its food. It prefers to nest in snow-free areas near the sea or on bare earth, short grass or high ridges. In winter it flies around the Antarctic, on winds called the “roaring forties.” In spring it heads north to coasts of South America, South Africa, Australia or New Zealand. The south polar skua is a real wanderer, with some ranging as far north as Alaska, Greenland and the North Russia coast. 
Food & Hunting : The skua will consume a variety of prey or even carrion, but its favored food is penguin eggs and chicks raided from breeding colonies. In some areas, the skua may show a similar dependence on other seabirds (shags, terns, petrels or gulls). Sometimes the skua hunts alone, flying low over a penguin colony, looking for an exposed egg or poorly defended chick.A pair of skuas will also cooperate to distract a group of adults. When it can, the skua will steal food from other birds.When penguins are feeding their chicks, skuas often fly down to catch the shrimplike krill as it is regurgitated. The skua also attacks seabirds in flight, twisting and turning for several minutes as it follows every evasive maneuver of its quarry, then grabbing a wing or a tail to force the victim to discard its hard-won food. 
Behavior : True to its aggressive nature, the skua defends its nest with ferocity. In a dense colony, the frenzied conflict of neighbors rarely ceases. An intruder is threatened with a “long call” — lifting its wings in a V, it points its bill at the sky and utters a long shriek. If this fails to repel the intruder, it mounts an attack — a swift aerial chase or a lively fight on the ground. If humans stray too close to a nest, the occupant will “dive-bomb” them, often striking home with its beak or claws. The skua protects its hunting grounds with equal vigor. On the Antarctic Peninsula, its range overlaps with that of its relative, the south polar skua. Although the skua is outnumbered eight to one, it relentlessly drives other species away from the penguin colonies. 
Breeding : The skua returns to its nesting sites from late October to mid- November, having been away about seven months. The skua is faithful to its mate of the previous year. If a female finds herself without a mate (if, for example, he has died) she’ll try to find another male or even a male south polar skua. Hybrid pairs always involve a female brown skua and a male south polar skua, never the other way around. Egg-laying is synchronized with the breeding cycle of nearby penguins; they provide a good supply of food when chicks are born. Breeding success doesn’t vary much; most pairs raise two young. 

Bill : The powerful, hooked bill identifies the skua as a predator. It uses this fearsome weapon to catch and kill large penguin chicks or fish and defend its territory from intruders. 
Wings : Large, strong wings give the brown skua speed and agility in the air, letting the skua chase other birds and force them to give up their prey. 
Plumage : The brown skua’s plumage is usually browner than its relative, the south polar skua. Its head has a dark cap. In old age, the feathers turn gray and in the breeding season, the neck is flecked with gold. 
Feet : The webbed feet typical of seabirds help the skua when swimming and diving to catch fish.

Weight : 3–4 lbs.
Length : 24-26"
Wingspan : 60"
Sexual Maturity : 6 years
Breeding Season : October-April 

After feeding on a large penguin chick, the skua leaves only feet, leg bones, pelvic girdle and skin.