Arctic Skua Diet and Size: Feeding Habits, Predators, and Measurements

Arctic Skua Diet and Size: Feeding Habits, Predators, and Measurements

Arctic skuas are aggressive birds which are also called pirate birds. This is because they steal food from other birds by aggressively flying all around them, climbing high into the sky before swooping whilst performing acrobatic twists and turns.

These intimidation tactics are enough to force the other birds to drop whatever food they have caught. The arctic skuas then swoop on the food in mid air.

In some cases, the arctic skuas will join forces with other members of the same species to bully their victims into giving up their food. In this article we’ll take a closer look at the diet of the arctic skua, its feeding habits, its main predators and much more.

Keep reading for all of the information you need about the dietary habits of the arctic skua.

The Dietary Habits Of The Arctic Skua

Let’s start by looking at what arctic skuas eat and what they feed their babies.

What Does An Arctic Skua Eat?

The diet of the arctic skua consists mainly of fish, in the Shetland Isles for example, the number of breeding pairs of arctic skuas dropped significantly after there was a sharp decline in the sand eel population off the coast.

When they can’t find fish of their own, arctic skuas will put on an aerobatic display to intimidate other birds to drop their regurgitated food. The skuas then swoop and catch the food before it hits the water.

They will also eat dead birds and small mammals, eggs and young chicks. Even the eggs or chicks of other members of their own colony!

What To Feed A Baby Arctic Skua? 

The chicks are precocial which means they are born with their eyes open and covered in down. This allows them to leave the nest after 24 to 48 hours.

The young chicks stick around the breeding ground with their parents who take turns in feeding them. They eat regurgitated fish often stolen from other birds in the local area or caught out at sea.

The parents will also feed the young regurgitated dead birds, small mammals or even the chicks from surrounding nests. Whilst the young chicks are still with their parents they learn how to hunt for food and how to intimidate other birds in order to steal their food.

Once the young reach around 26 to 30 days old, they leave their parents and head out to sea. Typically not returning to the nesting grounds for 2 or 3 years.

Breeding Habits Of Arctic Skuas

Arctic Skua Flying

The adult arctic skua doesn’t reach sexual maturity until the age of 2 or 3 and spends its early life out at sea pretty much all of the time. On becoming an adult, the arctic skua will fly to the north and west coasts of Scotland including the Shetland Isles and Orkney Islands to breed.

They make a shallow nest with their feet on the ground typically on a slight mound with a clear view of the sea. This depression is then lined with whatever plant material is available in the location of the nest.

The female will lay 2 eggs around 58 x 40 mm in size. Each egg weighs around the same as 2 alkaline AA batteries (48 grams). The eggs are incubated for around 26 days or there abouts by both parents.

Do Arctic Skuas Mate For Life?

Arctic skuas become sexually mature at around the age of 2 or 3. They find a mate and typically stay with the same partner all of their life. Unlike aquatic warblers who are sexually promiscuous, arctic skuas remain with the same mate all through their life.

The Size & Weight Of Arctic Skuas

We already mentioned that arctic skua eggs weigh around 48 grams which is around the same as 2 alkaline AA batteries. Let’s now look at the size and weight of adult arctic skuas.

How Much Does An Arctic Skua Weigh?

Fully grown adult arctic skuas weigh anywhere between 330 to 570 grams. That’s as little as a 330 ml empty can of pop or as much as a standard full size football. 

The female is around 16% heavier than the male as well as being around 5% larger. This is known as reversed sexual size dimorphism (RSD) and is common among owls, falcons, hawks and skuas.

How Big Is An Arctic Skua ?

Arctic skuas, along with long-tailed skuas and pomarine skuas are one of the three smallest skuas worldwide. Adult arctic skuas are around 40 to 45 cm long which is roughly the same size as a standard bowling pin. With a wingspan of approximately 110 to 125 cm.

Those impressive wings can propel the arctic skua at speeds up to 50 kilometres per hour or around 14 metres per second! Which allows them to put on their impressive aerial displays that they use to intimidate other birds in order to steal their food.

Are Arctic Skuas Under Threat?

Arctic Skua

The arctic skua population has dwindled in the north and west of Scotland since 1986. There are two theories as to what’s caused this. Which are; a drastic reduction in the sand eel population off the coasts of Scotland. 

Or the increased population of great skuas which are competing for the same foods and the predatory behaviour of the great skuas towards arctic skua nests and young.

However, this is not the case elsewhere in the world. There are currently an estimated 500,000 to 10 million arctic skuas worldwide.

What Eats An Arctic Skua?

Apart from the predatory behaviour of great skuas, arctic skuas are also under threat from other predatory birds like owls as well as foxes and even other members of their own colony.

The main predation of arctic skuas occurs in the breeding grounds. The eggs and young chicks are the most vulnerable. Even though both parents are present during the rearing of the young, they often lose one egg or chick.

Foxes, owls and other arctic skuas are often found stealing eggs or young chicks from the nest. If the parents see any predators in the area of the nest they will feign a broken wing to lure the predator away from the area.

Once the young birds leave the breeding ground they fly out to sea and remain at sea for the first couple of years of their lives. They remain pretty safe whilst out at sea and only return to land to breed after they reach adulthood at the age of around 2 or 3.

When in the breeding ground, arctic skuas are at their most vulnerable. They are ground nesters which makes the nests hard to protect and disguise.

Even other arctic skuas will prey on the young of neighbouring nests. Stealing eggs and young chicks if left unattended. In recent studies it has been stated that only around 50% of arctic skua eggs laid, hatch and reach full maturity.

Where Can I See Arctic Skuas In The UK?

Arctic skuas can only usually be seen in the far west and north of Scotland and the Scottish Isles. This includes the Shetland and Orkney Islands.

However, it is also possible to see arctic skuas along the coastline of the UK further south as they start their long migration to the southern hemisphere. For instance we once saw an arctic skua on a beach in North Norfolk.

SEE ALSO: Aquatic Warbler Eggs to Chicks: Hatching, Development, and Fledging

Frequently Asked Questions

What is the population of the Arctic skua?

The worldwide population of the arctic skua is estimated to be somewhere between 500,000 to 10 million birds.

What is the nickname of the arctic skua?

Arctic skuas have the nickname of parasitic jaeger which means parasitic hunter and refers to their terrorising other birds in order to steal their food.

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