Black-headed Gull - Chroicocephalus ridibundus

Black-headed gull (Chroicocephalus ridibundus) are a small gull, loud and sociable. Their name is something of a misnomer, with the head being dark brown in colour rather than black. Their body and neck is white, pale grey wings with black wing tips, and a red beak and legs (fig. 1) (Svensson, 2020). 

Black-headed gulls are a widespread breeder, nesting both inland and coastally. They will breed in a range of habitats (typically near water) such as marshes, gravel pits, bushes, and roofs. They have a varied diet and are largely opportunistic and adaptable - whilst their main prey items are insects, earthworms and marine invertebrates they will also eat fish, berries, and agricultural grain (Harris et al, 2024). Black-headed gulls typically live to around 11 years old, breeding at 2 years (Harris et al, 2024).

Population & Distribution:
Britain and Ireland hosts around 2-4% of the global black-headed gull breeding population. Between 1998-02 and 2015-21 the black-headed gull coastal nesting population has decreased by 28% across the UK (Harris et al, 2024).

Along the east coast, the Forvie NNR breeding black-headed gull colony is believed to be one of the largest in Scotland. Breeding has also occured in other coastal sites over the years such as Loch of Strathbeg, Cruden Bay, St Fergus Terminal to varied success (fig. 2). Forvie is the only location with consistent monitoring and submission of data, so it is difficult to get a clear picture of the whole coastline. The east coast also hosts important roost sites for black-headed gull, with large numbers recorded at Loch of Strathbeg, along the Ythan, Donmouth, Peterhead over the years (North East Scotland Bird Reports).

Conservation Status:
Scottish Biodiversity List: Priority Species (NatureScot, 2020)
Black-headed gull are an Amber listed species (Stanbury et al, 2024).

Factors Impacting Black-headed Gull:
Along the east coast it seems that many black-headed gull breeding colonies are impacted by predation and also vegetation/scrub encroachment. The North East Scotland Bird Reports detail predation over the years from foxes, otters, stoats, and other gulls which has impacted on breeding success. However, the implementation of predator proof fencing at Forvie NNR for the tern colony is perhaps what has preserved the black-headed gull colony and allowed it to thrive.
There was a breeding colony at Cruden Bay up to 550 pairs in 2005, but it subsequently collapsed. This was believed to be due to vegetation succession. In 2018 and 2019 Forvie NNR carried out clearance of dense rosebay willowherb (Chamerion angustifolium) stands and attributed the large numbers of black-headed gull nesting to this clearance (North East Scotland Bird Reports).

Highly Pathogenic Avian Influenza (HPAI) has impacted black-headed gulls both locally and nationally, with an 11% decline in the UK reported between 2018 pre-HPAI baseline figures and 2023 (Tremlett et al, 2024).

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