Meet the Arctic skua, a captivating avian resident of the Arctic region. Although having a striking appearance, it’s a skillful robber in the air. Let’s delve into the captivating world of these majestic birds, exploring their unique features and many more interesting facts.
1. Arctic skuas have 2 morphs
The Arctic skua, belonging to the skua family Stercorariidae, is a sizable seabird that closely resembles a common gull. It displays two prominent color variations: light and dark phases.
The light morph displays a cap that is light brown-black, a back that is grey-brown, and underparts that are white. It has a brown-black tail and wings, black legs and bill, a white throat, and yellowish cheeks. There is typically a dark band across the breast, but it may not always be present. On the other hand, the dark morph exhibits primarily dark brown plumage, frequently with a distinctively darker cap.
Their juveniles also the dark and light phases, but the colors are quite different. In the light phase, the Arctic skuas display a coat of warm brown feathers with hints of yellow-brown or red-brown tones. Their head and neck are adorned with distinct bars, while their belly exhibits a mottled pattern.
In contrast, the young birds in their dark phase exhibit a rich chocolate-brown plumage, featuring a darker head and neck, and less pronounced mottling compared to their counterparts in the light phase. Besides, numerous birds display intermediate color that falls between these two distinct extremes.
To get the plumage of mature birds, these young need to wait for approximately three to four years.
The Arctic skewers exhibit a notable trait with its two slender central tail feathers that extend past the rest of its tail. These straight and pointed feathers serve as distinguishing characteristics of this particular species.
They have a size of about 46 cm in length, taking into account the extended central tail feathers, and weigh between 350 to 600 g. The wingspan of these birds spans approximately 1.2 meters. In terms of appearance, there are no differences between the 2 genders.
The Arctic skua is one of the most remarkable species in the Arctic region. Their breeding grounds span the coastal areas and tundra of the North Pacific and North Atlantic, encompassing locations such as Iceland, Svalbard, Faeroes, Norway, northern Scotland, and the Russian coast.
These skuas in Svalbard engage in pair breeding on the coastal tundra, except for the northeastern areas of the archipelago.
In their non-breeding season, these skuas adopt a pelagic lifestyle in their main habitats consisting of coastal areas, estuaries, and inlets. These areas are commonly visited as they embark on migration journeys towards the south.
3. They are sea robbers
Arctic skuas are known for their aggressive behavior as seabirds. To get food, they use 2 different foraging tactics, which are determined by their breeding habitat.
In inland regions and specific coastal areas, these birds apply a predatory strategy by hunting chicks, eggs, and small rodents. However, in coastal colonies, their behavior shifts to a kleptoparasitic nature, where they steal food from other birds, such as puffins, Arctic terns, kittiwakes, auks, especially Brünnich’s guillemots. This behavior has earned them the moniker “avian pirates.”
These aggressive sea birds possess a remarkable talent for stealing food from other species while in mid-flight. They agily chase after other birds, compelling them to relinquish their airborne spoils. Being overwhelmed by their unwavering pursuit and synchronized assaults, their victims often have to let go of the fish they have caught. That’s why Arctic skuas are called parasitic jaegers in North America. The term “jaeger” originates from the German word for hunter.
These birds have a diverse diet. They eat mammals, fish, carrion, insects, smaller birds, and invertebrates. They even scavenge discarded waste from ships and boats.
The sea jaeger birds have quite a few predators, including American minks, and ravens, as well as larger birds of prey such as falcons and eagles. Their eggs and young are usually eaten by Arctic foxes.
Arctic skuas lead a predominantly airborne existence, spending the majority of their lives soaring above the ocean. However, they do touch down on land during the breeding season, which takes place in the Arctic summer.
These sea birds are migratory birds. Every year, they undertake extensive long-distance migration, reaching the Southern Hemisphere sometime between October and November. They typically begin their return trip by February or March. Although being solitary species, they can sometimes fly in small flocks, consisting of up to 10 birds.
These migratory creatures possess the remarkable ability to cover extensive distances during their journeys. On occasion, they may veer off course and find themselves in tropical areas such as South-East Asia.
When the breeding season arrives, they form pairs and set their territories. On the shoreline, these avian creatures usually mark their territories by opting for raised mounds as strategic lookout spots. Over time, these mounds, composed of various materials such as bones or rocks, gradually accumulate the birds’ poop, providing a fertile environment for plant growth.
To communicate, they use their unique vocalizations. Their primary call consists of a sequence of three to four distinct calls, which can increase to 12 calls when they are in flight. They even utilize brief vocalizations to establish their dominance within their territories or during confrontations with other avian creatures or even humans.
Arctic skuas are fast, especially when they pursue other birds to steal their food. They are estimated to dive and soar at speeds surpassing 50 mph (80.4 kph).
While Arctic skuas may present some degree of danger. They can display aggression and have the potential to harm humans, however, their attacks are not too dangerous that can cause fatal.
During the summer months, the Arctic skua engages in breeding activities within the Arctic tundra. These species are monogamous, they mate for life and return to the same nesting ground each year. They only change their partners due to death or if one of the partners is unable to reach the nesting site to breed.
The male will take the responsibility to choose the nest sites. The nest is a shallow depression and is adorned with plant materials. After mating, the female lays a clutch of brownish-olive eggs. The clutch size typically ranges from 1 to 4 eggs, with an average of 2 eggs. These eggs will be incubated for 25 to 30 days by both the male and female.
Just like ground-nesting gulls, the young can leave the nest within a short span of time, although most of them prefer to stay with their parents. In the nest, the offspring are fed with regurgitating food and are protected by their parents till they fledge at the age of 5 weeks old.
Arctic skuas reach sexual maturity at approximately 4 years old. Their typical lifespan is about 12 years. However, some of them can live longer, about 25 years. On the IUCN Red List, they are listed as Least Concern.