Fr: Goéland à ailes grises
Ang: Glaucous-winged Gull
All: Beringmöwe
Esp: Gaviota de Bering
Ita: Gabbiano di Bering
Nd: Beringmeeuw
Sd: gråvingad trut

Photographers:

Tom Grey
Tom Grey's Bird Pictures & Tom Grey's Bird Pictures 2

Ken Havard 
His Bird Pictures on IBC et Flickr gallery

William Price
PBase-tereksandpiper & Flickr William Price

Simon Tan
PBase Bird galleries

Text by Nicole Bouglouan

Sources:

HANDBOOK OF THE BIRDS OF THE WORLD Vol 3 by Josep del Hoyo-Andrew Elliott-Jordi Sargatal - Lynx Edicions - ISBN: 8487334202

FIELD GUIDE TO THE BIRDS OF NORTH AMERICA - National Geographic Society - ISBN: 0792274512

Avibase (Denis Lepage)

BirdLife international

HBW Alive

Audubon

All About Birds (Cornell Lab of Ornithology)

Animal Diversity Web (University of Michigan Museum of Zoology)

Bird Web (Seattle Audubon Society)

Wikipedia, the free encyclopaedia

What Bird-The ultimate Bird Guide (Mitchell Waite)

Identification and ageing of Glaucous-winged Gull and hybrids 
By Enno B Ebels, Peter Adriaens & Jon R King

Alaska Seabird Information Series

Eastside Audubon - Pink-legged Gulls: Glaucous-winged, Western, and Herring

Interbreeding of the Glaucous-winged Gull and Western Gull in the Pacific Northwest
By J. Michael Scott

 

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Glaucous-winged Gull
Larus glaucescens

Charadriiformes Order – Laridae Family

INTRODUCTION:
The Glaucous-winged Gull is a large Laridae of the northern Pacific Ocean. It breeds in extreme NE Eurasia and NW USA. It winters S to N Japan and NW Mexico (Baja California). It is rarely seen far from salt or brackish water, and occurs along the coasts, including coastal cities and towns.  
The Glaucous-winged Gull commonly hybridizes with the Western Gull and other large gull species in NW USA. Both breeding adult and first winter are paler than the Western Gull, but darker than the Glaucous-winged Gull. In breeding plumage, the hybrid adult has black wingtips and dark eyes.
This species has stable to increasing populations, and is not currently threatened.    

DESCRIPTION OF THE BIRD:
Biometrics:
Length: 61-68 cm
Wingspan: 132-137 cm
Weight: 900-1250 g

The Glaucous-winged Gull adult in breeding plumage has white head, body and tail. Mantle and upperwing are pale grey, although some populations are darker (N and E populations from Alaska to Japan). The wingtips are median grey with white spots near the tip. We can see a conspicuous white trailing edge.
The thick bill is yellow with red gonydal spot. The eyes are dark brown. Legs and webbed feet are pink.

With American Black Oystercatcher

Both adults are similar. In non-breeding plumage, they have head, neck and breast densely streaked with greyish-brown, involving hooded appearance. The red gonydal spot becomes indistinct.

The juvenile and the 1st winter have brown to grey-brown plumage with subtle mottling. Head and neck become paler during the first winter. The bill is blackish.

The 2d winter has mostly pale grey mantle and scapulars, and paler rump.
The 3d winter resembles adult, but it has brown-tinged coverts and smaller white wingtips. There is sometimes a partial, dark tail band. The bill is pinkish with black tip.

RANGE:
The Glaucous-winged Gull breeds in Kamchatka and Commander Islands, E through Aleutian and Pribilof Islands, and S Bering Sea to S Alaska, and then SE to N Oregon.
It winters from Bering Sea to N Japan and NW Mexico (Baja California).  

HABITAT:  
The Glaucous-winged Gull frequents mainly both salt and brackish waters along coasts. It can be seen in bays, estuaries, beaches, islands, mudflats and nearby offshore waters, and it is often attracted to harbours and fishing ports.  
It breeds on islands with barren, rocky or vegetated ground. It favours small, flat, less forested islands with bare rocky areas and low herbaceous cover. It also nests in bays and estuaries, on cliffs and grassy meadows. In Alaska, it nests at inland lakes and often occurs in urban parks, on breakwaters and roofs.

CALLS AND SONGS: SOUNDS BY XENO-CANTO   
The Glaucous-winged Gull’s calls are similar to those of the Herring Gull, a variety of prolonged wails, chuckles and hisses. The “long call” is a loud series of spaced “haaaw” notes. It also gives a moaning, deep “aah-aah-aah” and the alarm call is a soft “ga-ga-ga” if an intruder approaches.

BEHAVIOUR IN THE WILD:
The Glaucous-winged Gull feeds on a wide variety of marine items such as fish, limpets, clams, mussels, sea urchins, barnacles, crabs and squid. However, it also takes carrion, bird’s eggs, small mammals and some plant material. The diet varies depending on the location. While swimming on rivers, it feeds on remains of bear-killed or dying fish (salmon), and may steal food to raptors as they are feeding with the gulls. They are highly opportunistic.

It forages while walking or swimming, but it also plunges into water from the air to catch a prey. Clams and crabs are dropped onto rocks to break them open.

The Glaucous-winged Gull breeds in dense colonies. They are territorial on their breeding grounds, and frequent squabbles may occur between males. However, it becomes very gregarious outside breeding season, even with other gull species.
It often returns to the same colony on several following years, and usually re-pairs with the same mate from the previous year. They often pair for life.

The Glaucous-winged Gull hybridizes with the Western Gull, where their ranges overlap in Washington and Oregon. Hybrid’s appearance varies considerably, but they usually have light mantle, dark wingtips and dark eyes.

The Glaucous-winged Gull is sedentary or migratory, but usually, great numbers move S after breeding. Some adults reach Central California from late August, with peak in mid-winter. They return N by early April.  
They are common in N Japan and Hokkaido in winter, with some birds reaching Tokyo and E and S coasts of China. Vagrants are reported in Hong Kong, Hawaii, Illinois (USA) and Newfoundland in Canada, with vagrant individuals from Morocco and Canary islands.
The flight is powerful and direct with slow, measured wingbeats.

REPRODUCTION OF THIS SPECIES:   
The Glaucous-winged Gull arrives at colonies in February/March, but the egg-laying occurs later, from early May to early June in Alaska.
They breed in dense colonies of up to 2000 pairs, but this species may also nests solitary. The nest can be placed on the ground, on cliffs, roofs and other artificial structures. Both adults build the nest, usually a shallow depression lined with grass, seaweed and debris. Several nests can be started by a pair, but only one will be complete and occupied.

The female lays 2-3 olive to yellow-green eggs with brown and grey markings. Both adults share the incubation during 26-29 days. At hatching, the chicks are greyish-brown with blackish spots above, and the underparts are tinged yellowish. They often leave the nest two days later, and remain in the vicinity of the nest, where both parents feed them. They are able to fly between 37 and 53 days after hatching, usually at 45 days old. They leave the colony two weeks later.  
Adults and young are often killed by Bald Eagles at colonies.

PROTECTION / THREATS / STATUS:  
The Glaucous-winged Gull has expanded its range N and S, leading to more hybridization with the Western Gull in Washington State, USA. But it also hybridizes with the Glaucous Gull in Alaska and Commander Islands, and with the Slaty-backed Gull on the coasts of Kamchatka and Commander Islands, Russia.  
The global population was estimated to number >570,000 individuals in 2006. The overall population trend is increasing, but some populations are stable.
The Glaucous-winged Gull is currently evaluated as Least Concern.