Audouin's Gull

Distribution, movements and phenology

The Audouin’s Gull breeds between April and August, from the Atlantic coast of Morocco to Mainland Portugal and in various Mediterranean countries. It is a partially migratory species, wintering in the Mediterranean and along the north-west African coast as far south as Senegal (Billerman et al. 2026).

Although there are historical records (Leal & Lecoq 2006; Catry et al. 2010a), the species only became permanently re-established in Portugal from 2008 onwards, on Deserta Island in Faro (Moniz 2015). In the Algarve, the species is most common from March to October, with several hundred individuals remaining throughout the winter. Breeding adults in the Algarve forage in deep, productive waters up to approximately 100 km from the colony during incubation (Pereira et al. 2025b). After hatching, most adults remain near the colony, although some move north to Morocco and the Mediterranean. Individual tracking data from 76 birds fitted with GPS, from colonies in Portugal and Spain, indicate year-round use of the continental sub-area of the EEZ. The distribution of the birds was concentrated mainly south of the Algarve, although use has also been recorded along the south-west coast, between Setúbal and Sagres. No occurrences were recorded in the Azores and Madeira, which explains the scarce or non-existent observations of the species in these regions (Correia-Fagundes et al. 2021; Birding Azores 2022).

Abundance and population trends

The global population has been estimated at around 20,000 pairs (Oliveira et al. 2025b), with a declining trend (BirdLife International 2025). In Portugal, the species began nesting again in the early 2000s in the salt pans of Castro Marim, albeit irregularly and with very low or zero productivity, due to heavy predation pressure (Leal & Lecoq 2006). From 2008 onwards, it became a regular resident on Deserta Island, where the population grew steadily and spread to Culatra Island. In 2024, 5,591 breeding pairs were recorded on Barreta and 1,701 on Culatra. In recent years, an expansion of the breeding population towards the west coast of the Mainland has also been noted (Equipa Atlas 2022). Consequently, this population has achieved Good Environmental Status for the abundance indicator.

Ecology and habitat

The Audouin’s Gull is generally found near the coast, though it may also frequent the continental slope. Its diet consists mainly of epipelagic fish, but also includes demersal and benthic species (Matos et al. 2018). It also feeds heavily on discards from commercial fisheries, particularly trawlers and purse seiners (Bécares et al. 2015; Matos et al. 2018). It nests colonially on rocky or sandy islands, sandy peninsulas and salt pans. With the collapse of some historic colonies, the Audouin’s Gull has demonstrated an ability to colonise new sites, including less traditional environments such as harbours and urban areas (Oliveira et al. 2025b).

Threats and conservation

The Audouin’s Gull is particularly sensitive to a reduction in fishing discards and the intrusion of predatory mammals into colonies, factors which have led to population declines and dispersal to other areas (Oro et al. 2004). Human presence, both in nesting areas and foraging grounds, constitutes another significant threat, as it can significantly disturb the birds, forcing them to abandon their sites and compromising breeding success. The species is also susceptible to habitat loss and degradation, bycatch, competition with other species, marine pollution, offshore energy structures, disease outbreaks and the increasing effects of climate change (Oliveira et al. 2025b).

Autor

Tânia Nascimento

Owners/sources of tracking data

Gonzalez-Solis 2016j, Ramos 2021a, Vitor H. Paiva (MARE-UCoimbra)