Great Skua Life Cycle: Nest Building To Fledging (and everything in between)

The great skua or “Bonxie” as it is also known is a large, heavy seabird which is around the same size as a herring gull. It is also known as a “pirate of the sea” because it steals food from other birds.

The great skua breeds in the UK on the islands of Scotland and is well known for dive bombing anyone that happens to get too close to its nesting site. 

Great skuas will chase other seabirds like gulls or gannets and steal the food that these birds have caught. They will also eat smaller birds like puffins. They fly to the Spanish and African coasts to overwinter and return to their breeding grounds in spring.

The great skua is the largest seabird found in the UK and is dark brown in colour. It has gold coloured streaks and a dark cap and a thick bill. It is easy to identify when in flight as it shows white flashes on its wings.

The name “Bonxie” is derived from an old Norse word meaning “dumpy” and refers to its shape and size. Keep reading to find out more about these fascinating birds.

How Long Does A Great Skua Live?

The great skua is a bird that can live for many years. According to ring records, some great skuas can live as long as 34 years! With the record of 35.9 years being recorded.

If an intruder attempts to enter the breeding colony, great skuas will resort to physical attacks and sometimes lengthy fights.

They typically win these aggressive encounters due to their relatively large size. However, injury can cause the great skua to become weakened leading to a shorter lifespan.

However, there are currently around 9,600 breeding pairs of great skuas in the UK. Europe wide, there are an estimated 17, 250 breeding pairs, but there have been reports of a drop in the population of the great skua as a result of the current avian flu epidemic.

How Fast Can A Great Skua Fly?

The great skua has been recorded flying at a speed of 50 miles per hour. That’s around 80 kilometres per hour or 22 metres per second. They have an easy flight pattern with slow wingbeats and brief glides.

They are a very agile bird, and flap their wings frequently when soaring which they can maintain for extended periods. This speed and agility is a useful trait when chasing other birds for their food.

Are Great Skuas Aggressive?

Great skuas are an aggressive predatory seabird. Well known for chasing and intimidating other birds like gannets and gulls to steal their food.

Great skuas will also hunt for small birds, eggs and small mammals like rodents and rabbits. They display their most aggressive behaviour when defending their nesting colonies.

If they detect any intruders, they will fly high into the air and swoop down on the intruder at great speed. These defensive attacks often end in physical assaults. 

There have even been recorded sightings of great skuas attacking polar bears that strayed too close to their nests.

What Is A Great Skua’s Habitat?

Great skuas breed in the Faroe Islands, Iceland, Norway and on Scottish islands. There are a few great skuas that breed on mainland Scotland and in the north west of Ireland.

They breed on coastal moorlands and rocky islands. When not breeding the great skua spends most of its life out at sea. Only returning to land during the breeding season.

They migrate to warmer waters off the coast of Spain and Africa during the winter.

How Long Does It Take For A Great Skua To Build A Nest?

Great skuas reach sexual maturity at around the age of 7 to 8 years. They tend to nest in loose colonies and both birds make a shallow depression in the ground in an open area. Typically in areas slightly higher than their surroundings.

They line the nest with local plant material. The nest typically takes 1 to 3 days to build but the female often rejects the siting of the first few nests. 

This can add to the time needed to make a nest. Which generally takes 3 to 5 days overall.

Eggs

Let’s take a look at the early life of the great skua. Starting with their eggs.

When Do Great Skuas Lay Eggs?

Once great skuas reach the age of sexual maturity, they find a mate and between them build a nest. This typically starts in May with the male putting on an aggressive display.

He will start fights with other males over food with lots of aggressive wing raising in order to show his white wing patches.Great skuas are monogamous and typically form pairs that remain together for life.

They will usually return to the same nesting ground year after year.

How Many Eggs Does A Great Skua Lay?

The female will usually lay 2 eggs which are incubated for around 28 to 32 days by both parents. 

During this time the parents will take it in turn to sit on the eggs while their partner is out on the hunt for food.

What Do Great Skua Eggs Look Like?

The eggs of the great skua are a buff or olive colour and covered in dark brown spots or freckles. The colour and markings on the eggs act as a perfect camouflage when viewed from above.

The eggs are around 70 x 50 mm in size and weigh around 91 g. The shell makes up around 7% of the overall weight of the egg.

How Long Do Great Skua Eggs Take To Hatch?

The eggs are incubated for around 28 to 32 days before hatching. Both parents take turns incubating the eggs and hunting for food.

In most cases the female (the larger of the pair) spends longer hunting for food and covers a larger distance while foraging than the male.

Chicks

Now let’s look at the chicks after the eggs hatch.

How Many Chicks Does A Great Skua Have?

Young pairs typically raise one chick successfully whereas more mature pairs tend to successfully raise both chicks to the fledging stage. Experienced parents typically manage to raise both chicks whereas younger pairs often only manage to rear one chick.

This is often caused by their inability to find enough food close to the nesting site leading to one of the chicks starving. As the pair become more experienced, they tend to have the ability to find enough food to keep both hungry chicks growing and getting stronger.

When Do Great Skua Chicks Open Their Eyes?

Great skua chicks are precocial which means they are born covered in a pale pink/grey brown down and with their eyes open. They can walk almost as soon as they hatch and typically leave the nest 24 to 48 hours after hatching.

They stay with their parents for a while learning how to hunt and forage for food. As well as other survival skills before fledging.

When Do Great Skua Chicks Fledge?

Great skua chicks stay with their parents for around 40 to 50 days after hatching. When they leave their parents, they will fly out to sea and possibly not see land again for many years.

They will return to land to breed once they reach sexual maturity at around the age of 7 to 8.

SEE ALSO: Arctic Skua Vs Great Skua: Key Differences Explained

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