Arctic Jaeger
Scientific name: Stercorarius parasiticus
Family stercorariidae
- Phenology Mainland
- Wintering and passage migrant
- Phenology Madeira
- Passage migrant
- Phenology Azores
- Passage migrant
- IUCN Global Status
- Mainland Conservation Status
- Madeira Conservation Status
- Azores Conservation Status
Data
Maps
Occurrence | Spring
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Presentation
Distribution, movements and phenology
The Arctic Jaeger breeds between May and August in Arctic and sub-Arctic regions, wintering mainly in the southern hemisphere off the coasts of various continents (Billerman et al. 2026), but also in subtropical waters (van Bemmelen et al. 2024b). In Portugal, it is mainly found along the western Mainland coast, occurring particularly during migration, but also in winter (Ramírez et al. 2008; Catry et al. 2010a), this region being the northernmost limit of its wintering range in the Atlantic Ocean (van Bemmelen et al. 2024b). In the Azores, it occurs almost exclusively during migration, particularly from mid-July to late October, being most frequent in August and September. In Madeira, it occurs mainly between August and October (Meirinho et al. 2014).
Individual tracking of 17 birds fitted with GLS devices, originating from Norway and Greenland, confirms the extensive use of the Portuguese EEZ, mainly during the non-breeding period, with some birds arriving earlier, probably having completed breeding sooner.
Abundance and population trends
The European population has been estimated at between 39,900 and 56,200 pairs, representing 20% of the global population (BirdLife International 2025) and showing a declining trend (Langlois Lopez et al. 2026). On the Mainland, observations from land are more likely during periods of bad weather, when strong westerly winds bring birds closer to the coast, with hundreds sometimes recorded on certain days (Moore 2000). During the post-breeding migration in 2015, 1,146 birds were counted passing south from Cape Carvoeiro (Elmberg et al. 2020). Based on the data used for the environmental status assessment, an estimate of between 8,700 and 27,200 individuals was obtained for the continental shelf in 2024.
The negative trend in this population, combined with the fact that it has not achieved Good Environmental Status for the abundance indicator on the Mainland, appears to align with negative trends documented for various populations across its range (Langlois Lopez et al. 2026). In the case of Madeira and the Azores, there is no information on population trends, thus preventing an assessment of its environmental status.
Ecology and habitat
Outside the breeding season, it mainly frequents the waters of the continental shelf, though it also occurs beyond this (O’Hanlon et al. 2024; van Bemmelen et al. 2024b; Billerman et al. 2026). It may nest colonially or solitarily, in coastal areas or on islands. During the breeding season, when nesting near colonies of other seabirds, it obtains a considerable proportion of its food through kleptoparasitism. In the tundra, it has a largely generalist diet that includes small passerines and their chicks, wader chicks and other waterbirds, rodents, insects and berries (Billerman et al. 2026). In Portuguese waters, it steals food from various species of seabirds, particularly terns and gulls (Catry et al. 2010a).
Threats and conservation
The species appears to be stable globally. However, it has suffered significant declines in its main colonies, most notably in the North Atlantic (Langlois Lopez et al. 2026). This trend is likely linked to declines in other seabird species. In its breeding grounds, it may also be affected by human persecution (BirdLife International 2025).
Autores
Rob van Bemmelen, Olivier Gilg, Tânia Nascimento
Owners/sources of tracking data
Borge Moe & Sveinn Are Hansen, Olivier Gilg, Rob van Bemmelen
van Bemmelen RSA, Moe B, Schekkerman H, Hansen SA, Snell KRS, Humphreys EM, Mäntylä E, Hallgrimsson GT, Gilg O, Ehrich D, Calladine J, Hammer S, Harris S, Lang J, Vignisson SR, Kolbeinsson Y, Nuotio K, Sillanpää M, Sittler B, Sokolov A, Klaassen RHG, Phillips RA & Tulp I (2024b). Synchronous timing of return to breeding sites in a long-distance migratory seabird with ocean-scale variation in migration schedules. Movement Ecology 12: 22. Bibliografia:
Ramírez I, Geraldes P, Meirinho A, Amorim P & Paiva V (2008). Áreas Importantes para as Aves Marinhas em Portugal. Projecto LIFE04NAT/PT/000213 – Sociedade Portuguesa para o Estudo das Aves. Lisboa. Bibliografia:
O’Hanlon NJ, van Bemmelen RS, Snell KR, Conway GJ, Thaxter CB, Aiton H, Aiton D, Balmer DE, Hanssen SA, Calladine JR, Hammer S, Harris SJ, Moe B, Schekkerman H, Tulp I & Humphreys EM (2024). Atlantic populations of a declining oceanic seabird have complex migrations and weak migratory connectivity to staging areas. Marine Ecology Progress Series: 730: 113-129. Bibliografia:
Moore CC (2000). Movimentações invulgares de aves marinhas junto ao cabo Carvoeiro. Pardela 13: 7-10. Bibliografia:
Meirinho A, Barros N, Oliveira N, Catry P, Lecoq M, Paiva V, Geraldes P, Granadeiro JP, Ramírez I & Andrade J (2014). Atlas das Aves Marinhas de Portugal. Sociedade Portuguesa para o Estudo das Aves. Bibliografia:
Langlois Lopez S, Snell K, van Bemmelen R, Pokrovskiy I, O’Hanlon N, Boertmann D, Gilg O, Green M, Hanssen SA, Harrison A-L, Moe B, Santos I, Smith PA, Systad GH & Humphreys EM (2026). Global population status of the migratory Holarctic species Arctic skua Stercorarius parasiticus. Bird Conservation International 36: e1. Bibliografia:
Elmberg J, Hirschfeld E, Cardoso H & Hessel R (2020). Seabird migration at Cabo Carvoeiro (Peniche, Portugal) in autumn 2015. Marine Ornithology 48: 231-244. Bibliografia:
BirdLife International (2025). IUCN Red List for birds. Downloaded from https://datazone.birdlife.org on 30.11.2025. Bibliografia:
Billerman SM, Keeney BL, Kirwan GM, Medrano F, Sly ND & Smith MG (eds.) (2026). Birds of the World. Cornell Laboratory of Ornithology, Ithaca, NY, USA. Bibliografia:
Catry P, Costa H, Elias G & Matias R (2010a). Aves de Portugal, Ornitologia do Território Continental. Assírio e Alvim, Lisboa Glossário:
A species or parameter that reflects the state of an ecosystem or environmental changes. Glossário:
Monitoring the movements of individuals using tracking devices. Glossário:
The direction of change in the size of a population over time (increase, decline or stability). Glossário:
A concept defined under the Marine Strategy Framework Directive (MSFD), referring to the condition of the elements of the marine environment, including birds. It aims to assess whether ecosystems are healthy, balanced and capable of supporting ecological functions and human uses in a sustainable manner. The ultimate goal is for the components and ecosystems to achieve Good Environmental Status. Glossário:
A group of birds associated with coastal or inland wetlands, generally found in habitats such as mudflats, saltmarshes, estuaries, lagoon margins, sandy areas and flooded zones. Some of these species also use the sandy and rocky coasts of Portugal. Glossário:
Under the United Nations Convention on the Law of the Sea, coastal states are entitled to declare an EEZ comprising maritime area beyond their territorial waters. The national EEZ is delimited by an imaginary line situated 200 nautical miles from the coast, separating national waters from international or shared waters. Within its EEZ, each state has rights such as the exploitation of marine resources, the conduct of scientific research and the regulation of fishing by foreign vessels. Glossário:
The name given to the extensive plains with low-growing vegetation and no trees, characteristic of Arctic and sub-Arctic regions. The tundra is generally a very cold region with low precipitation. Glossário:
Referring to the period following breeding. Glossário:
The portion of the seabed that begins at the coastline and slopes gently downwards to the continental slope (where the slope is much steeper). On average, the continental shelf extends to a depth of 200 metres. Glossário:
A period generally corresponding to the winter months, which may include part of autumn. Glossário:
A small device attached to birds to study their large-scale movements (usually migration), which works by recording light intensity (from which the duration of night and the local midday time are estimated, and consequently the latitude and longitude on each day). Glossário:
A feeding method in which one individual steals food from another.
