Black-headed gulls were among the birds most heavily hit by the 2023 avian influenza outbreak, with over 4,000 birds killed in Great Britain by early May; similarly high mortality rates were also reported from France, the Netherlands, Italy and Germany.
The black-headed gull is a bold and opportunistic feeder. It eats insects, fish, seeds, worms, scraps, and carrion in towns, or invertebrates in ploughed fields with equal facility. It is a noisy species, especially in colonies, with a familiar "kree-ar" call.
It displays a variety of behaviour and adaptations. Some of these include removing eggshells from the nest after hatching, begging co-ordination between siblings, differences between sexes, conspecific brood parasitism, and extra-pair paternity. They are found in a variety of different habitats.

