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

Many birdwatchers eagerly await the return of the pomarine skua to UK shores from late April to early May. They are easily recognisable by their spoon shaped tail feathers, black crown and face mask, dull pink bill with the black tip, pale yellow cheeks and dark grey breast band.

Most have a bright white belly and brown wings, mantle and undertail which reaches all the way down to that spoon shaped tail. And who can forget the white marks on the underwings and broad white patch on the upper wing?

Not all adult pomarines have these colourings and markings however, around 20% are known as “dark morph” birds. This small select group have an almost black plumage covering their bodies with a grey bill base.

But you can identify these birds by their white wing patches which are common to both dark and light morph pomarine skuas. These birds are also known as pomarine jaegers.

Jaeger is an old Germanic word meaning hunter and is fitting for these aggressive seabirds that swoop on other species, intimidating them and making them drop their food. Which is then stolen by the pomarine skuas.

Keep reading to find out more about the life cycle and other interesting facts about this fascinating bird.

How Long Does A Pomarine Skua Live?

Pomarine skuas have an average lifespan of around 15 years. However, there have been recorded cases where the rings have revealed that some pomarine skuas have lived for around 30 to 35 years, but these incidents are rare.

They reach sexual maturity anywhere between the age of 2 to 8 and typically breed across the northern tundra regions of Russia, Canada and Alaska. With a few breeding in the far north east of Norway.

How Fast Can A Pomarine Skua Fly?

Like other skuas, the pomarine skua is an acrobatic flyer who is skilled at soaring high into the sky before swooping down at great speed to intimidate other birds to drop their food.

During these swoops, the pomarine skua can reach speeds of up to 50 miles per hour (80 kph). That’s around 22 metres per second!.

Are Pomarine Skuas Aggressive?

Pomarine skuas can be very aggressive especially when defending their nesting sites from intruders. When intruders get near to nesting sites, pomarine skuas will make loud calls and fly towards the intruder with slow wing beats.

They will also stand their ground and raise their large wings displaying those white flashes. 

They are also far more physical when attacking other birds in order to steal their food than other members of the skua family. Pomarine skuas tend to use far more brute force than the typical acrobatic flying skills exhibited by Arctic skuas for example.

What Is A Pomarine Skua’s Habitat?

Outside of the breeding season the pomarine skua is pelagic (remains out at sea) and favours coastal waters in tropical or subtropical regions. They are often seen around large fishing vessels where they steal food from other birds.

Pomarine skuas come inland to breed and prefer Arctic tundra regions.

The pomarine skua can be found in breeding colonies from Norway, Russia, Canada and Alaska. They nest in areas with pools and areas with hills in boggy landscapes.

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

Once Pomarine skuas find a mate, they both make a scrape nest by making a small depression in the surface of the ground using their feet and breasts. This can take anywhere from a few hours to a few days.

The extra time is due to the female often rejecting the first few attempts before finally settling on what she considers to be the perfect nest site. The nest is typically lined with local plant material.

Eggs

Now let’s look at the reproduction habits of the pomarine skua. Starting with when they lay eggs, how many eggs they lay and so on.

When Do Pomarine Skuas Lay Eggs?

Pomarine skuas breeding season coincides with the time of year when lemmings are also breeding. As lemmings are their main source of food when breeding, pomarine skuas nests are typically built in areas close to a large lemming population.

Pomarine skuas breeding season is between June to August in Arctic or subArctic tundra. After completing their nest building activities, the female will lay 1 to 2 eggs in the shallow scrape nest lined with plant material (typically grass).

How Many Eggs Does A Pomarine Skua Lay?

In most cases, the female pomarine skua will lay 1 to 2 eggs but there have been some nests recorded containing 3 eggs. The male and female share the incubation of the eggs.

Taking it in turns to sit on the eggs or fly off in search of food. They will bully other seabirds into giving up their food, kill smaller birds (including gulls and ducks), catch their own fish if necessary, scavenge fish and fish parts from fishing boats as well as hunting and killing lemmings and other small mammals for food.

What Do Pomarine Skua Eggs Look Like?

Pomarine skua eggs are buff or dark olive in colour with darker brown and grey spots or freckles. They are around 57 to 74 mm in length and around 40 to 49 mm in width.

The colouration and markings act as a perfect camouflage, looking like rocks or pebbles when viewed from above. This helps to keep the eggs safe from any would-be predators if the nest was left unattended for any reason (which is highly unlikely).

How Long Do Pomarine Skua Eggs Take To Hatch?

Both parents take turns incubating the eggs which take around 25 to 28 days to hatch. 

Once the eggs are hatched, the parents need to find an abundance of food to feed up the youngsters and make them strong enough to fend for themselves.

Chicks

Now let’s look at how many pomarine chicks survive and other interesting facts.

How Many Chicks Does A Pomarine Skua Have?

The survival rate of the chicks is often dependent on the number of eggs laid. We saw earlier that some pomarine skuas lay 3 eggs, invariably this leads to all 3 eggs not surviving to the hatching stage.

This is because the parents incubate the eggs on their feet due to the sparseness of the nest in such a cold environment. As the placing of the eggs on either parent’s feet is haphazard at best, none of the eggs tends to survive.

Whereas, when only 2 eggs are laid, one can fit on each of the parents responsible for incubating at that time’s feet. Another factor that influences the survival of the chicks is how level the nest is.

For some reason, pomarine skuas will disregard any egg that rolls away from the nest even slightly. Which could explain why the female is so fussy on the position of the nest in the first place. As well as why it takes her so long to choose a suitable nest site.

However, assuming that all of the above has been followed, both chicks will hatch within a day or two of each other. But that doesn’t mean that both will reach the fledgling stage.

The first born will always be that much larger than its nest mate and will actively exclude the other chick from gaining any food from the parents. In many cases, the older chick will even kill its sibling.

Having said that often both chicks do make it to the fledgling stage.

When Do Pomarine Skua Chicks Open Their Eyes?

Pomarine skua chicks are precocial which means they are hatched with their eyes open. They are also covered in a thick down and have the ability to leave the nest after around 24 to 48 hours.

The young chicks remain dependent on their parents for food for around 14 days after hatching. With both parents feeding them with small mammals like lemmings, fish, small birds and anything else they can scavenge.

When Do Pomarine Skua Chicks Fledge?

The chicks of the pomarine skua typically fledge after around 21 to 28 days of hatching. The parents also leave the nesting ground as soon as the youngsters attain their independence.

The young pomarine chicks will fly out to sea and not return to land again until they are around 7 to 8 years old. On their return they will find a mate and bring their own young into the world.

SEE ALSO: Manx Shearwater Life Cycle: Nest Building To Fledging (and everything in between)

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