Callum Macgregor

An exclusively marine, medium-sized seabird, breeding on rocky cliffs along sea coasts and offshore islands (Ainley et al. 2021). It has a circumpolar distribution, with the European strongholds in the British Isles, Iceland, Denmark (Faroe Islands) and Norway (Keller et al. 2020). There is a clear gradient from the high-latitude populations being migratory (Svalbard), through partially migratory mid-latitude populations (N Britian, Faeroes, Iceland) to resident and locally dispersive birds in lower latitudes (Irish, North & Baltic Seas).

Season of assessment

B

Population trendIncreasing
Population size
(min-max, best estimate)		2990000-4430000,3660000
Red List categoryLC
Franks, S., Fiedler, W., Arizaga, J., Jiguet, F., Nikolov, B., van der Jeugd, Ambrosini, R, Aizpurua, O., Bairlein, F., Clark, J., Fattorini, N, Hammond, M., Higgins, D, Levering, H., Skellorn, W., Spina, F, Thorup, K. Walker, J., Woodward, I. and Baillie, S.R. (1) (2022) Online Atlas of the movements of European bird populations. https://migrationatlas.org EURING/CMS (1) Principal investigator
Map

Overall Connectivity for Guillemot

Guillemots are largely dispersive rather than migratory, although the juveniles/immatures travel further than the adults (Álvarez, Pajuelo, 2004). High-latitude populations migrate to escape sea ice (Ainley et al. 2021). During migration and in winte birds breeding in the British Isles are mostly along the Atlantic coast from S Portugal to N Norway (primarily in the N Sea and W European coasts), the Faeroes and Iceland; very few birds reach the Baltic Sea and the W Mediterranean. The W & SW European population is mostly resident, while Baltic & W Scandinavian breeders move mainly within the region. Birds breeding on Helgoland disperse within the N Sea region and Icelandic breeders are locally dispersive, although some birds have been found as far away as the British Isles and the Faeroes. Intercolony movements are regular (Halley & Harris 1993).

Recoveries by Condition for Guillemot

Alhtough protected in most of Europe, Guillemots are hunted legally in Iceland, the Faeroes and Greenland. Most recoveries are since the mid-1980s, primarily in Jun-Jul (~81% of total). Most recoveries are in NW (74%) and N Europe (16%). Recoveries of dead birds decreased from 84% pre-1961 to almost none after 1990, whilerecoveries of live birds increased from 4% to 83% - mostly due to recaptures, including resightings. Shooting was more important in the past - 39% of all recoveries pre-1961 (mostly in Iceland, S Norway and Denmark), and 8% in 1961-1990. Nowadays 7% of all recoveries are a result of oil spills and by-catch casualties. There are clear ringing hotspots at sites in the British Isles, Germany, Sweden and Norway and recoveries are almost all coastal.

Annual Movements for Guillemot

Within Europe, post-breeding dispersal starts from late Jun (mid-latitudes) until late Jul (Barents Sea). Guillemots undergo a flightless wing-moult after the breeding season (Ainley et al. 2021). N Icelandic breeders moult (Aug-Sep) locally and off the coast of E Greenland, while they are found both locally and in the region of the Mid-Atlantic ridge SW of Iceland in winter (Linnebjerg et al. 2018). British Isles breeders are found along the Atlantic coasts from SW to N Europe mostly in Nov-Feb, but as late as Apr. Pre-breeding concentrations close to the breeding sites are usually formed in Feb (Flint & Golovkin 1989). Breeding cliffs are occupied from early Mar (British Isles; Wernham et al. 2002) to Apr (Barents Sea); in the Baltic Sea and high-latitude populations timing is dependent on sea ice.  

Strong migratory connectivity is found across the NE Atlantic (Merkel et al. 2021).

Connectivity by Month by Region for Guillemot

Dispersal movements after the breeding season start in mid- to late summer. British Isles breeders are along the Atlantic coastline from the Iberian Peninsula to N Scandinavia from late autumn to early spring. Irish Sea breeders concentrate in winter in the Bay of Biscay, while those from E UK colonies disperse mostly in the North Sea (Harris et al. 2015, Dunn et al. 2020). Birds breeding in the Baltic Sea are mostly found locally duirng migration and winter, although some move towards the British Isles and Norway. The Barents Sea is an important autumn staging and wintering area for the C Norwegian population (Lorentsen & Ray 2012). Return to breeding sites is in early to mid-spring. There are few encounters of high-arctic populations.

Boris Nikolov

References

Statistics Map
N records N individuals N recoveries
Mapped data*
Total available data
*Mapped data include only distant (>= 50 km) recoveries
References Map
1989 . The Birds of USSR. Auks (Alcidae). Nauka, MoscowEditor(s): Flint, V. E., Golovkin, A. N.
2002 . The Migration Atlas: movements of the birds of Britain and Ireland. T. & A.D. Poyser, LondonEditor(s): Wernham, C.V., Toms, M.P., Marchant, J.H., Clark, J.A., Siriwardena, G.M., Baillie, S.R.
2020 . European Breeding Bird Atlas 2: Distribution, Abundance and Change. European Bird Census Council & Lynx Edicions, BarcelonaEditor(s): Keller, V., S. Herrando, P. Voříšek, et al.
Ainley, D. G., D. N. Nettleship, and A. E. Storey 2021 . Common Murre (Uria aalge), version 2.0. In Birds of the World Link to Article (DOI: https://doi.org/10.2173/bow.commur.02) Cornell Lab of Ornithology, Ithaca, NY, USA
Álvarez, D., Pajuelo, A. A. F.2004 . Differential migration in a wintering population of Common Guillemots Uria aalge affected by the Prestige oil spill. Ardeola 51: 451–454
Dunn, R.E., Wanless, S., Daunt, F., Harris, M. P., Green, J. A. 2020 . A year in the life of a North Atlantic seabird: behavioural and energetic adjustments during the annual cycle. Sci Rep 10 article no.: 5993
Halley, D. J., Harris, M. P. 1993 . Intercolony movement and behaviour of immature Guillemots Uria aalge. Ibis 135: 264–270
Harris, M. P., Wanless, S., Ballesteros, M., Moe, B., Daunt, F., Erikstad, K. E.2015 . Geolocators reveal an unsuspected moulting area for Isle of May Common Guillemots Uria aalge. Bird Study 62: 267–270
Linnebjerg, J.F., Frederiksen, M., Kolbeinsson, Y., Snaethórsson, A. Ö., Thórisson, B., Thórarinsson, T. L. 2018 . Non-breeding areas of three sympatric auk species breeding in three Icelandic colonies. Polar Biology 41: 1951–1961
Lorentsen, S.-H., Ray, M. 2012 . Inter-breeding movements of common guillemots (Uria aalge) suggest the Barents Sea is an important autumn staging and wintering area. Polar Biology 35: 1713–1719
Merkel, B., Descamps, S., Yoccoz, N.G., Grémillet, D., Fauchald, P., Danielsen, J., Daunt, F., Erikstad, K.E., Ezhov, A.V., Harris, M.P., Gavrilo, M., Lorentsen, S.H., Reiertsen, T.K., Systad, G.H, Thórarinsson, T. L., Wanless, S., Strøm, H. 2021 . Strong migratory connectivity across meta-populations of sympatric North Atlantic seabirds. Mar. Ecol. Prog. Ser. Link to Article (DOI: https://doi.org/10.3354/meps13580)

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