Great Black-backed Gull - Larus marinus

Great black-backed gull (Larus marinus) are the largest gull species in the world, with a bulky body and thick neck.  Adult breeding plumage consists of a white body, dark grey/black wings, dull pink legs and a 'heavy 'yellow beak with a red spot (fig. 1) (Svensson et al, 2020).

Great black-backed gull largely breed along rocky coastlines or coastal grasslands with a small number nesting inland (e.g. on rooftops). Their diet is varied and generalist, feeding on prey such as fish and marine invertebrates, other birds and their eggs, and small mammals alongside human rubbish (e.g. fishery discards and at refuse tips). They exhibit kleptoparasitic behaviour, harassing other birds for example gulls and sea ducks to steal their food (Svensson et al, 2020; Harris et al, 2024). Great black-backed gull typically live to around 20 years old, breeding at 5 years (Burnell et al, 2023; Harris et al, 2024)

Population & Distribution:
Around 7% of the global great black-backed gull breeding population is hosted by Britain and Ireland, with 48% of this population found in Scotland (fig. 2) (Burnell et al, 2023; Harris et al, 2024). Great black-backed gull are common along the east coast throughout the year. They breed in very small numbers along the east coast, with some localities recording nests in single digits (fig. 3). Breeding has been recorded previously at sites such as Longhaven, Bullers of Buchan, Cruden Bay, Sands of Forvie, and on Aberdeen rooftops. Great black-backed gull utilise a number of roost sites up the east coast including Loch of Strathbeg, Inverugie and Peterhead, and the Ythan Estuary (North East Scotland Bird Reports).

Conservation Status:
Great black-backed gull are a Red listed species due to a severe breeding population decline and a moderate non-breeding population decline over at least 25 years (Stanbury et al, 2024). During the latest seabird census Seabird Counts 2015-21 it was found that the great black-backed gull population in Scotland had declined by 63% since the previous census Seabird 2000 in 1998-2002 (Burnell et al, 2023).

Factors Impacting Great Black-backed Gull:
Drivers of great black-backed gull population decline are not fully understood, but it is theorised they are facing several factors that are having a cumulative negative effect (Langlois Lopez et al, 2023). It is thought that the introduction of the fishery discards ban could be reducing food availability (DEFRA, 2015), along with potential prey distribution changing with climate change (from fish and marine invertebrates to other birds/seabirds). 

Great black-backed gull have been deemed high risk for collisions with offshore wind turbines. This is particularly due to their typical flight altitude overlapping with turbine blade heights, combined other factors such as a moderate amount of nocturnal flight activity (Furness et al, 2013).

Highly Pathogenic Avian Influenza (HPAI) has impacted great black-backed gull populations significantly, with a 20% decline overall in the UK reported between 2015-21 pre-HPAI baseline figures and 2023 (Tremlett et al, 2024).

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