First record of a large breeding colony of the Lesser Black-backed Gull Larus fuscus in mainland Africa

Abstract

A breeding colony of the Lesser Black-backed Gull Larus fuscus was discovered at the Khenifiss lagoon on the Atlantic coast of southern Morocco. In June 2022, 222 nests were counted and, in 2023, 62 nests were present. Nests were built on sandy-clay soil on a natural saline flat without any vegetation cover. The mean calculated egg volume (69.10 ± 6.69 cm3; n = 33) was similar to that reported for European populations of this species. Predation was the main cause of breeding failure. This remarkable discovery constitutes the first evidence of reproduction of Lesser Black-backed Gulls in mainland Africa, thereby extending the species’ known breeding range southwards by ∼2 000 km. This finding holds considerable implications for understanding this species’ adaptability to new environments and the population dynamics driving range expansion.