Pomarine Jaeger
Stercorarius pomarinus
Visual Identification
Appearance
The Pomarine Jaeger is a robust seabird with a dark brown upper body and white underparts. It features a distinctive black cap, pale cheeks, and a strong, hooked bill. The bird's central tail feathers are elongated and twisted, giving it a unique silhouette in flight.
During the breeding season, adults develop a golden collar. Juveniles are mottled brown all over and gradually acquire adult plumage over several years. Light and dark color morphs exist, with intermediates between these extremes.
Size
Length
46cm to 51cm
Wingspan
110cm to 138cm
Weight
540g to 910g
Colours
Males and females have similar plumage
Primary Colour
Brown White
Secondary Colour
Black Grey
Beak Colour
Black
Leg Colour
Black
Habitat and Distribution
Habitats
Woodland
Garden
Wetland
Coastal
Urban
Farmland
Grassland
Desert
Tundra
Rainforest
Mountain
Savanna
Distribution
Pomarine Jaegers breed in the Arctic tundra across northern North America and Eurasia. They prefer coastal areas and offshore waters during migration and winter.
These birds are found in the North Atlantic, North Pacific, and Arctic Oceans, with some individuals reaching as far south as Australia and South Africa.
During migration periods, they can be observed along the coasts of the United States, Canada, and the United Kingdom. Wintering birds may be seen off the coasts of southern US states and occasionally in the waters around the British Isles.
Elevation Range
Sea level to 300 meters
Climate zones
Arctic, Temperate, Tropical
Distribution Map
This map gives you a rough idea of where you might spot a Pomarine Jaeger. The coloured areas show countries where these birds have been seen.
A few things to keep in mind:
- Birds might not be everywhere in the coloured areas, for example, they may be present around the coast of that country
- Where birds live can change with seasons and available food
- This map is quite simple - it doesn't show exact locations
We're working on making our maps even better! Soon, we hope to show you:
- More detailed maps for bigger countries, including state and region
- How birds move around during different seasons
Distribution by Region
Behaviour and Ecology
Bird Attributes
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Share your thoughtsBird Attributes Explained
Our bird attributes system rates various aspects of a bird's capabilities on a scale of 0-100, based on data from field observations, scientific studies, and expert knowledge.
Attribute Categories:
- Agility: Manoeuvrability, speed, and grace in flight or movement.
- Strength: Physical power, often correlating with size and hunting abilities.
- Adaptability: Ability to thrive in various environments or changing conditions.
- Aggressiveness: Territorial behaviour and assertiveness, particularly during breeding seasons.
- Endurance: Stamina, often seen in migration patterns or foraging behaviours.
Understanding the Ratings:
- 0-20: Very Low
- 21-40: Low
- 41-60: Average
- 61-80: High
- 81-100: Very High
Remember, these attributes are relative to other bird species and don't necessarily indicate superiority.
Hover over the icon next to each attribute for more information.
Tap the icon next to each attribute for more information.
Agility
Reflects the bird's manoeuvrability, speed, and grace in flight or movement.
The Pomarine Jaeger displays remarkable agility, capable of rapid direction changes and impressive aerial manoeuvres. Their ability to chase and harass other seabirds in flight demonstrates exceptional aerial prowess.
Strength
Indicates the bird's physical power, often correlating with size and hunting abilities.
As a robust seabird with a strong, hooked bill, the Pomarine Jaeger possesses considerable strength. Their ability to fly at speeds up to 60 km/h when pursuing other birds and their kleptoparasitic behaviour indicate significant physical power.
Adaptability
Represents the bird's ability to thrive in various environments or changing conditions.
Pomarine Jaegers show high adaptability, thriving in diverse environments from Arctic tundra to open oceans. Their opportunistic feeding habits and ability to survive in harsh climates further demonstrate their adaptability.
Aggressiveness
Measures the bird's territorial behaviour and assertiveness, particularly during breeding seasons.
Known for their aggressive kleptoparasitic behaviour, Pomarine Jaegers frequently chase and harass other seabirds to steal food. Their territorial nature during breeding season and willingness to confront potential predators also indicate high aggression.
Endurance
Reflects the bird's stamina, often seen in migration patterns or foraging behaviours.
As long-distance migrants capable of traversing vast oceanic expanses, Pomarine Jaegers exhibit remarkable endurance. Their ability to withstand harsh Arctic conditions during breeding and extensive oceanic journeys during migration supports this high endurance rating.
Diet
Pomarine Jaegers are opportunistic feeders, primarily consuming fish, mollusks, and crustaceans. They often obtain food by harassing other seabirds, forcing them to drop or regurgitate their catch.
During the breeding season, they also prey on small mammals, birds, and eggs found in their tundra habitat.
The availability of lemmings is vital to the survival and success of breeding, with brown rodents forming up to 90 percent of their diet during this period. In years when lemming populations are poor or non-existent, Pomarine Skuas are unable to breed.
Behaviour
Pomarine Jaegers are known for their aggressive kleptoparasitic behavior. They often chase other seabirds to steal their food. They are strong, agile flyers capable of rapid direction changes and impressive aerial maneuvers.
During the breeding season, they become territorial and may perform elaborate courtship displays, including synchronized flights and vocalizations.
Vocalisation
Pomarine Jaegers have a variety of vocalizations, including a harsh, guttural 'kyow-ow' call often heard during territorial disputes or when chasing other birds. A harsh, chattering ‘which-yew, which-yew’ call is heard when feeding at sea.
During courtship, they produce a series of mewing sounds and low whistles. Their calls are generally deeper and more resonant than those of other jaeger species.
Nesting & Breeding
Pomarine Jaegers form monogamous pairs and breed in the Arctic tundra. Courtship involves aerial displays and vocalizations, typically occurring in late spring. Nests are simple scrapes on the ground, often on raised areas with good visibility.
Females usually lay two olive-green eggs with dark spots. Both parents share incubation duties, which last about 25-28 days. The eggs are well-camouflaged against the tundra vegetation.
Chicks are precocial and leave the nest shortly after hatching. They fledge after about 30-35 days but may remain with their parents for several more weeks before migrating south.
Conservation and Status
Global Conservation Status
While currently listed as Least Concern, Pomarine Jaegers face threats from climate change affecting their Arctic breeding grounds. Oil spills and marine pollution pose risks during migration and wintering periods.
Conservation efforts focus on protecting critical habitats and reducing human impacts on marine ecosystems.
Birdwatching Tips
- Look for Pomarine Jaegers along coastlines during migration periods
- Observe their distinctive flight pattern with deep wing beats and glides
- Watch for kleptoparasitic behavior as they chase other seabirds
- Use a spotting scope to identify the twisted central tail feathers
- In North America, check coastal areas in spring and fall for migrating individuals
Additional Information
Quick Facts
Other names:
Pomarine Skua
Family:
StercorariidaeAverage Lifespan
12 to 15 years
Max Lifespan
32 years
Predators
Adult Pomarine Jaegers have few natural predators, but Arctic foxes, large gulls, and occasionally snowy owls may prey on eggs and chicks.
Did You Know?
- Pomarine Jaegers can fly at speeds of up to 60 km/h (around 38 mph) when pursuing other birds.
- Their scientific name 'pomarinus' means 'having a lid,' referring to the horny cere covering the base of their bill.
- These birds can drink saltwater, thanks to special glands that remove excess salt from their bloodstream.
References
- 1 2 3
website: BirdLife International. 2018. Stercorarius pomarinus. The IUCN Red List of Threatened Species 2018: e.T22694240A132534251.
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