Birds

Arctic Tern Sterna paradisaea Imeqqutaalaq



      image courtesy of: en.wikipedia.org/wiki/



    Distribution:
      image courtesy of: identify.whatbird.com/



    Status:

      image courtesy of: en.wikipedia.org/wiki/


    
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Description:

Gracefully elegant bird in flight, and Greenland's only tern. This small, slender white bird is well known for its long yearly migration. It has the farthest yearly journey of any bird. Traveling from its breeding grounds in the Arctic to its wintering grounds off of Antarctica, it can cover over 25,000 miles (40,000 km). The Arctic tern arrives in Greenland in May-June and departs in August-September, having two summers. Also the Arctic tern sees more daylight than any other creature on the planet.

The Arctic tern flies as well as glides through the air and performs most of its tasks in the air. It lands once every one to three years to nest. Once the nesting is done it takes to the sky for another long southern migration.

The Arctic tern is very noticeable for its extended tail streamers. These are long and deeply forked. It is a white medium-sized tern with a black cap. They have a length of about 13-15 inches (33-39 cm). The wings are white with some dark at the tips. The Arctic tern has a red beak and red feet.

Their diet mainly consists of fish and small marine invertebrates. Being long-lived birds, they can reach up to 30 years old. There is an estimated one million individuals of this species.

These birds have a variety of calls. The two most common are their alarm calls. These are made when possible predators enter their colonies. They also have an advertising call which is social in nature and is made when returning to the colony and during aggressive encounters between individuals. Each call is unique to each individual tern. There have been eight other calls that have been identified from begging calls made by females during mating to attack calls made while diving at intruders.

Arctic terns mate for life. The courtship is made during the first time of nesting. The female will chase the male to a high altitude and then slowly descend, which is called the 'high flight'. The male will offer a fish to the female which is called 'fish flights'. After this, both birds will fly together and circle each other. Both parents will agree on a site for a nest. During the nesting time the male will feed the female. The female will lay from 1 to 3 eggs.

The nest is a depression in the ground and it is usually lined with bits of grass or similar materials. The eggs are camouflaged and both parents share the incubation duties. The eggs hatch after 22-27 days and leave the nest after 21-24 days. While they are nesting, the birds can be easily attacked by cats and other animals. The herring gull will steal eggs and hatchlings. The eggs are camouflaged to help prevent this.

The Arctic tern is one of the most aggressive terns, being fiercely defensive of its nest and young. Attacking human and large predators, the Arctic tern will strike the top or back of the heads. The birds are too small to cause any serious damage but are capable of drawing blood. Other species of birds can benefit from nesting near an area defended by Arctic terns.

The diet of the Arctic tern depends on the location and time but they are usually carnivorous (eats meat). Most cases they eat small fish or marine crustaceans. Sometime these birds may dip down to the surface of the water to catch prey close to the surface. They have been known to swoops at other birds to startle them and then take their catchings.

These birds prefer to breed in colonies on smaller islands, around inland lakes, or on coastal beaches. Numbers have declined sharply in West Greenland as a result of excessive egg collection, but terns are still fairly common between Nuuk and Upernavik. Infrequent breeder in dispersed colonies in the rest of Greenland. Worldwide these birds have circumpolar breeding distribution which is continuous. The Arctic tern's range
encompasses an area of approximately ten million square kilometers.

 


Source courtesy of: The Nature and Wildlife Guide to Greenland, Benny Gensbøl (2005) and wikipedia.org