The Parasitic Jaeger, or Arctic Skua as it is also known, is an agile seabird with a dishonorable means of finding food.
The Parasitic Jaeger is a medium-sized, gull-like seabird with long, angular wings and a broad, fan-shaped tail complete with two elongated central feathers. These birds occur in a dark, all-brown morph and a light morph with whitish underparts and heads, and a dark cap and chest band.
Both morphs have dark-gray to black bills, legs, and webbed feet. Paler or whitish bases to the primary feathers near the wing tips are visible in flight.
Both sexes have the same plumage, although female Parasitic Jaegers are typically 15 to 20 percent larger than males. Juveniles are difficult to identify accurately. They have variable barred, brownish plumage but lack the long middle tail feathers (rectrices) of adults.
Parasitic Jaegers are most easily confused with the smaller Long-tailed Jaeger/Skua and the larger Pomarine Jaeger/Skua. They are also superficially similar to the darker juvenile plumages of some gulls.
Parasitic Jaeger, light morph
Parasitic Jaeger, dark morph
Adult Parasitic Jaegers typically measure 16½ to 18 inches or 41 to 47 centimeters.
Male Parasitic Jaegers are smaller than females. Most males weigh 13.4 to 14.8 ounces (380 - 420 grams), while females are usually 16.2 - 18 ounces (460 - 510 grams).
These birds have long, pointed wings and a wingspan of 42½ - 46½ inches or 108 to 118 centimeters.
Parasitic Jaeger, light morph, standing on moss covered rock
Parasitic Jaegers produce a ‘long call’ on land or in flight that consists of three or four (sometimes up to twelve) rising nasal notes. They are usually silent away from their breeding grounds.
Parasitic Jaeger calling from nest site
Parasitic Jaegers are largely carnivorous birds that eat both live and dead prey. They are infamous for stealing food (kleptoparasitism) from other birds, harassing species like gulls in the air until they regurgitate their last meal, which the nimble Jaeger snatches mid-air or from the water below.
These fast-flying birds also prey on adult and nestling birds and their eggs, including songbirds such as the Snow Bunting, shorebirds like Sanderling, seabirds, and the young of wildfowl like the Common Eider. They also feed on carrion and catch mammals like Lemmings and Ground Squirrels.
Parasitic Jaeger in-flight looking for prey
Parasitic Jaegers generally inhabit coastal marine areas in the winter, particularly in habitats that support high numbers of seabirds that they can steal from. They breed in grassland, moorland, and tundra in the Arctic.
Parasitic Jaegers breed across the Arctic and northernmost shores of North America, Europe, and Asia. They overwinter predominantly around the coast of South America, Southern Africa, Australia, and New Zealand. They are widespread in the Atlantic and Pacific oceans on migration and some birds travel long distances over land.
Parasitic Jaegers are usually seen in flight, often chasing other sea birds. They are swift and agile on the wing, flying low and fast or high into the air in hot pursuit. They are comfortable on the water too, where they swim well with their webbed feet but never dive. Parasitic Jaegers usually only spend time on land when nesting, although they are known to roost on the shore in some areas.
The Parasitic Jaeger is generally uncommon, although it has a huge distribution and occurs in good numbers. The world population is estimated at 400,00 to 600,000 individuals.
Parasitic Jaegers are common summer breeding birds along Alaska’s north and west coasts and on the Aleutian Islands. They can be seen off the coast of the Lower 48 on migration to and from their breeding grounds, and some overlanding birds also stop at the Great Lakes in the fall.
Parasitic Jaegers breed in the tundra of northern Canada. They also occur in low numbers off the west coast of Canada between May and October during migration, when they may be seen both offshore and in coastal waters. Overland migrants are seen on Lake Ontario and the Lower St. Lawrence River.
Arctic Skuas can be seen virtually anywhere off the United Kingdom Coastline during their migration in the spring and autumn when they follow flocking seabirds like Terns. They can also be seen around breeding areas in northern Scotland and the surrounding Shetland and Orkney Islands in the summer.
Parasitic Jaeger landing in grassland
Parasitic Jaegers are known to live up to 33 years, although the typical lifespan of an adult is about 12 years. These birds first breed when they are three to seven years old.
Adult Parasitic Jaegers have few natural predators, although Great Skuas are known enemies. Their eggs and young are most vulnerable to Ravens, Great Skua, Arctic Foxes, and Mink.
Parasitic Skuas are protected under the Migratory Bird Treaty Act in the United States and the Migratory Birds Convention Act in Canada. They are also protected by the Wildlife and Countryside Act in the United Kingdom.
Parasitic Jaegers are a ‘Least Concern’ species on the IUCN Red List, and their population is considered stable. However, these birds are endangered in Europe and have a Red conservation status in the United Kingdom, where they nest in low numbers.
Parasitic Jaeger taking-off from a lake
Parasitic Jaegers nest on the ground at a site chosen by the male. Their nest is little more than a depression, created with the breast and feet. They may add some plant material, such as grass, moss, or twigs, but some birds simply lay their eggs on bare rock.
Parasitic Jaegers nest in the late spring and summer, with egg laying beginning between mid-May and mid-June, depending on location. Eggs hatch after 24 to 29 days, and chicks fledge after about a month. The young birds remain in their parent's territory for another two or three weeks.
Parasitic Jaegers usually lay two (1 - 3) spotted and blotched olive brown to grayish eggs, each measuring approximately 57 x 41 mm.
Parasitic Jaegers may mate for several consecutive years, although pairs do split, particularly if the partnership is new and they fail to reproduce. In such cases, the male usually retains the nesting colony, and the female seeks a new partner.
Nest of a Parasitic Jaeger with two eggs
Parasitic Jaegers are highly aggressive birds. They are real bullies of the bird world, intimidating and harassing other birds into surrendering their hard-caught meals. They are also aggressive toward their own kind and any potential enemies in the nesting season when they will swoop in at intruders and strike them with their feet.
Parasitic Jaeger in natural habitat
Parasitic Jaegers are long-distance migrants. Adults nest in the far north (Arctic and lower latitudes) and migrate across the equator to enjoy the Southern Hemisphere summer.
Parasitic Jaegers are a native breeding species in Alaska and Northern Canada. They occur off both the east and west coasts as migrants to and from their overwintering grounds around South America.
Arctic Skuas occur naturally in the United Kingdom. They nest in the north of Scotland and occur as passage migrants further south during the autumn and spring.
Parasitic Jaeger in-flight
Parasitic Jaegers are largely carnivorous, although they do eat some berries on their summer breeding grounds. Birds and their eggs and fish stolen from other seabirds are their most important food sources.
Parasitic Jaegers are tertiary consumers on the food chain. These birds eat some plant material, some animals that eat plants, and some animals that eat other animals.
Arctic Skua, Arctic Jaeger, Parasitic Skua
41cm to 47cm
108cm to 118cm
330g to 570g
Pomarine jaegers, or as pomarine skuas as they are known in the UK, are large seabirds that breed in the Arctic Circle, where they survive on a diet of lemmings. Winters are spent at sea, foraging for fish in tropical ocean waters.
Long-tailed jaegers are migratory seabirds, covering epic distances between their breeding grounds along the High Arctic coasts and their wintering territories in the open waters of the South Atlantic and South Pacific oceans. In the UK, they are more commonly known as long-tailed skuas.
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