Family Gulls, Terns, Skimmers (Laridae)

Least Concern

Thayer's Gull (Larus thayeri)


Taxonomy

French: Goéland de Thayer German: Thayermöwe Spanish: Gaviota esquimal
Taxonomy:

Larus thayeri

W. S. Brooks

, 1915,

Banks Island, Canada

.

A highly controversial and variable taxon, treated as a race alternatively of a broad L. argentatus or of L. glaucoides. Interbreeds with L. g. kumlieni in N Hudson Bay and E Baffin I, prompting latter treatment as a race of L. glaucoides. Although seemingly random pairing occurred in N Hudson Bay, a deficit of intermediate plumages suggested that post-mating isolation may exist. Pending further studies, thayeri is best treated as a discrete species. Merging it with L. glaucoides, as again proposed recently#R, would make latter species undiagnosable. Monotypic.

Distribution:

N Canada from Banks I E to N Hudson Bay and N Baffin I (E to vicinity of Home Bay), N through Ellesmere I to W Greenland (near Thule). Winters on Pacific coast from SW Canada (British Columbia) to NW Mexico (Baja California); regular but uncommon in Great Lakes region.

Descriptive notes

56–63 cm; 846–1152 g; wingspan 130–140 cm. Four-year gull. The most distinctive individuals combine the size and shape of the Iceland Gull L. glaucoides... read more

Voice

The long call is higher-pitched but slower than in the L. smithsonianus.

Habitat

Coasts of rocky islands, feeding also around fishing piers, rubbish dumps and settlements. Nests... read more

Food and feeding

Diverse diet. Inadequately studied on breeding grounds; non-breeders feed on refuse and scraps, offal and animal debris around settlements... read more

Breeding

Essentially unrecorded. Lays in early Jun. Small colonies of up to a few dozen pairs. Mainly on cliffs, usually with L. hyperboreus... read more

Movements

Migrates southwards and westwards, some reaching North Slope and Pacific coast at Alaska, others (... read more

Status and conservation

Not globally threatened (Least Concern). The global population during 2006–2011 has been estimated at 15,000–37,000 individuals  and has shown a marked... read more

Recommended citation

Burger, J., Gochfeld, M. & Garcia, E.F.J. (2017). Thayer's Gull (Larus thayeri). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/53981 on 11 December 2017).