Common Murre Uria aalge Scientific name definitions

David G. Ainley, David N. Nettleship, and Anne E. Storey
Version: 2.0 — Published August 6, 2021


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Geographic Variation

Northern birds blacker than southern forms. Amount of spotting on underwing coverts increases north to south among western North American populations (35), and incidence of melanism increases north to south in California populations (3); decrease in incidence of bridled morph north to south in the Atlantic (35, 36, 8; see below). Western to northern Pacific birds larger (culmen, wing length) than those in the south; Pacific birds larger on average than those of Atlantic; birds from Britain smaller than those farther north in eastern Atlantic (35; Appendix 1). Distinguishing forms from British Columbia and southeastern Alaska problematic; best character may be wing length (35). Manuwal and Carter (24) lumped British Columbia birds with U. a. californica based on known movements and a 300-km gap between British Columbia and Alaska colonies; however, Hipfner and Greenwood (37) showed British Columbia birds to be similar in size to Alaska rather than California birds (Appendix 1).

Bridled morph confined to Atlantic. In western Atlantic, a discontinuous cline exists in bridling frequency first noted in mid-1900s (38, 39), indicated mainly by highest frequency in the northern-most breeding sites and lowest in the southern-most sites. On basis of most recent survey (40, 41): northern Labrador, Nunaksuk Island, 1978–1979, 24.7% (71% as reported by Tuck [38] for 1953, and cited by Southern [39], possibly an error [T. R. Birkhead, personal communication] or anomaly within a breeding site having just 150 pairs); southern Labrador, Gannet Islands, 1978–1979, 18.7% (1953, 32%); northeastern Newfoundland, Funk Island, 1980, 19.5% (1956, 21%); southeastern Newfoundland, Witless Bay: Green Island, 1980, 20.9% (1959, 20.8%); and Great Island, 2000, 22.9% (AES); and southwestern Newfoundland, Cape St. Mary's, 1980, 17.3% (1953, 17.3%).

In eastern Atlantic during late 1970–early 1980s, cline more apparent: western Russia to Svalbard, 36–50%; Norway, 8–26%; Britain, 1–30%; France to Portugal 0–2% (41). Considering entire North Atlantic, minimum air temperatures during breeding (July) explained 60% of variation in bridling frequency. Sea-surface temperature explained only 35%, and was not related at all to bridling frequency in wintering areas (41). Therefore, bridled birds may have greater cold tolerance (39). In accordance, the survival rate of the bridled morph was negatively correlated to the winter temperature in the Barents Sea, while that of the non‐bridled morph was slightly positively correlated (42). Divergence in mitochondrial DNA among Atlantic colonies also consistent with bridling pattern, suggesting that U. a. aalge survived last glaciation in two refugia, one having low (southern), and the other high (northeast Atlantic) frequencies (43). Bridled birds also occur in clusters within colonies, most likely indicative of birds, especially females, recruiting close to where hatched (40); supported by genetic studies of Thick-billed Murres (Uria lomvia) indicating that kin groups occur within colonies (44).


Four subspecies are recognized here (45), although up to 8 subspecies (e.g., 36) have been recognized. Genetic evidence clearly distinguishes Pacific and Atlantic forms, apparently separated since Pleistocene (43; 46; see Systematics: Fossil History). Pacific populations show less genetic variation than Atlantic ones, in part because of current gene flow in the former and a history of fragmentation of populations in the latter (46).

For measurements of subspecies, see Appendix 1; breeding site locations and numbers given in Appendices 2, 3, 4, 5, 6, 7, 8, and 9.


Uria aalge aalge Scientific name definitions

Systematics History

U. a. aalge (Pontoppidan, 1763). Includes U. a. hyperborea Salomonsen, 1932; U. a. intermedia De Wijs, 1978; and U. a. spiloptera De Wijs, 1978.


Eastern North America, Greenland, and Iceland through Faeroes and Scotland to southern Norway and Baltic Sea.


Largest Atlantic form, with dark black back and conspicuous dark streaks on sides (relative to albionis).


Uria aalge hyperborea Scientific name definitions


breeds Svalbard through northern Norway and northwestern Russia east to Novaya Zemlya


Uria aalge albionis Scientific name definitions

Systematics History

U. a. albionis Witherby, 1923. Includes U. a. ibericus Bernis, 1949.


Ireland and southern Britain through Brittany to western Iberia; Heligoland.


Brownish-backed with inconspicuous stripes on the sides and small body size (relative to typical nominate aalge).


Uria aalge inornata Scientific name definitions

Systematics History

U. a. inornata Salomonsen, 1932.


Japan (northern Hokkaido) north through Sakhalin and Kuril Island to Kamchatka, whence east through Bering Sea, Aleutians, and western Alaska to northwestern British Columbia.


Larger than californica.


Uria aalge californica Scientific name definitions

Systematics History

U. a. californica (H. Bryant, 1861).


Western United States (northern Washington south to California).


Smaller than inornata, though both Pacific subspecies larger (especially wing length) than nominate aalge.

Related Species

Common Murre is closely related to Thick-billed Murre, with which it is sympatric over the northern portion of its Pacific and Atlantic ranges (cf. 47, 48, 5). Based on both morphological and molecular analyses (49, 50, 51), tribe Alcini is composed of the 2 murre species, Razorbill, and Dovekie (Alle alle). Based on sequence data from mtDNA and allozyme data, it appears that all three lineages arose in a rapid radiation (51), a finding which has been supported with additional analyses that include fossil taxa (52). Within the broader Alcidae, relationships are less clear, though it appears that this well-supported clade of 4 species is closely related to the Synthliboramphus murrelets (53, 54) and the guillemots (Cepphus; 51, 52)


Both murres breed in many of the same localities, where hybridization is sporadic (55). In southeastern Alaska, 6% contain Thick-billed Murre mtDNA; hybrids are fertile and backcross with Common Murre (56, 55). In a more recent study that included more extensive sampling in the Pacific, as well as additional molecular markers, Taylor et al. (57) identified similar levels of hybridization, with many hybrids being backcrossed individuals. A survey of birds from the Atlantic did not find strong evidence for hybridization between murres, contrary to findings from the Pacific (58). Hybrids, difficult to distinguish from Common Murre, exhibit a combination of both species' characteristics (59, 60, 61, 56). A suspected Common Murre × Razorbill hybrid was reported at Great Island, Newfoundland (62).

Fossil History

Genus Uria known from late Miocene, Pliocene, and Pleistocene deposits in both eastern (63) and western (64, 65) North America (see also 66, 67, 68). Uria likely originated in North Pacific, and spread secondarily to Atlantic (69, 66), although this is not totally clear (50; see also 70, 71). Common Murre reported from late Pleistocene (Palos Verdes Sandstone), Playa del Rey (Los Angeles County), and Mussel Rock (San Mateo County), California (63).

Bones of Common Murre and other northern species found in archaeological middens dating 2,060 yr ± 200 before present in Florida; species of other large auks found in middens dating 700 yr ± 100 before present (72). Presence in Florida corresponded to cool temperatures, when other northern aquatic species also common there (73). Midden remains in Newfoundland, British Columbia, and California consistent with currently constructed marine avifaunas in respective areas (see 74, 38, 75, 76).

Recommended Citation

Ainley, D. G., D. N. Nettleship, and A. E. Storey (2021). Common Murre (Uria aalge), version 2.0. In Birds of the World (S. M. Billerman, P. G. Rodewald, and B. K. Keeney, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.commur.02