Reproduction

Breeding takes place from May to September once they have returned from their migration to the southern hemisphere. Breeding tends to begin earlier in the south when compared with the north.

Their breeding site is either used by a single pair or a small group.

Each year a pair of Arctic skuas will return to the same site for breeding. They are monogamous and will retain their mate for life unless a death occurs. Pairs tend to breed every year though when conditions are not ideal they will delay breeding for a year.

Often pairs seem to be formed from one bird of each color morph. Evidence exists to suggest that the pale form of the Arctic skua may eventually be eliminated through sexual selection.

Two eggs are deposited in to a nest where they will be incubated for 25-28 days. Fledging occurs after 25-30 days.

Pairs are highly protective of their nest. When threatened they will dive bomb anything that comes close to the nest.

The first two years of their life are spent at sea before they come to land and breed.

Sexual maturity is reached between three and four years old.

Behavior

Arctic skuas spend most of their time flying over the ocean and will only come to land when it is time to breed.

Each year they perform a migration from the Arctic to the southern hemisphere. They arrive there in October and November and have left by February or March. Occasionally they may be blown off course and end up in tropical places such as South-East Asia.

Where they live on the coast Arctic skuas will survey their territory from mounds. These are formed on a large object such as bone or rock. Over time they accumulate large amounts of guano and plants will grow in them.

These birds may move around in groups of up to 10 at a time.

Predators and Threats

Natural predators of the Arctic skua include birds such as ravens and great skuas along with American minks.

Arctic skuas are sensitive to fluctuations in the population of sandeels (a group of fish with an eel like appearance). Declines in their stock will cause declines in Skua populations.

In parts of their range their is population control carried out to reduce stress on other species of birds.

Quick facts

Arctic skuas are also known as Arctic or Parasitic Jaegers. Jaeger comes from a German word for hunter reflecting their predatory nature.

The name skua comes from an Old Norse word for gull.

These birds inspired the name of the British Royal Air Force's first dive bomber, the Blackburn skua.