Characterization of anthropogenic materials on yellow-legged gull (Larus michahellis) nests breeding in natural and urban sites along the coast of Portugal

Fatty acids composition in yellow-legged (Larus michahellis) and lesser black-backed (Larus fuscus) gulls from natural and urban habitats in relation to the ingestion of anthropogenic materials

“…In addition to other areas, PBGaia mostly serves the Metropolitan Area of Porto, where Porto is the second largest city of Portugal (PORDATA, 2011) that lies on the right side of the mouth of the Douro River, close to sea. A known population of urban gulls dwell in the city of Porto throughout the year, using certain areas of the city to rest (Pais de Faria et al, 2021a), and public and private buildings to construct their rooftop nests (Lopes et al, 2020). On the contrary, RIAS serves mostly the Ria Formosa Natural Park which has five barrier sandy islands and two peninsulas that form a narrow strip of dunes that separate the lagoon from the Atlantic Ocean (Ceia et al, 2010), and is located relatively far from metropolitan and populated urban centres.…”

“…FA analysis is thus a useful tool to elucidate how anthropogenic materials may disturb metabolic pathways and to assess the less visible impacts of their ingestion, even though our results suggest that, at least with our sample of birds from a small period of time, there was no such effect. In the long run, urban gulls may be more exposed to several contaminants, pathogens (Alm et al, 2018;Sorais et al, 2020) and anthropogenic materials (Lopes et al, 2020(Lopes et al, , 2021 that might endanger gulls' health condition, survival and/or reproductive output.…”

“…However, the increase in anthropogenic food subsidies may act as an ecological trap as human-derived food has typically a poorer nutritional quality than the natural food resources (Auman et al, 2008), which may lead to a reduced growth rate and body condition (Annett and Pierotti, 1999;Pierotti and Annett, 1991). Animals exploiting these locations to forage may be susceptible to a higher exposure to contaminants, poisoning and pathogen infections (Seif et al, 2018;Sorais et al, 2020;Yorio et al, 2020), as well as an increased probability of interacting with anthropogenic debris materials such as glass, fabric, metal, paper and especially plastics (Lopes et al, 2020(Lopes et al, , 2021. In fact, coastal and more generalist seabirds such as gulls are particularly exposed to such anthropogenic materials (Kühn and van Franeker, 2020;Lopes et al, 2021) and vulnerable to the direct deleterious impacts of their ingestion, which may include the obstruction to food passage, stomach ulcers and perforations of the gastrointestinal tract, disturbance in the assimilation of nutrients, damage to tissues, morbidity and starvation (Gregory, 2009;Henry et al, 2011;Kühn et al, 2015;Lavers et al, 2014;Ryan, 1987).…”

Plenty of rooftops with few neighbours occupied by young breeding Yellow‐legged Gulls (Larus michahellis): Does this occur at the expense of their health condition?

“…Samples were collected in two natural, Deserta and Berlenga Islands, and two urban, Peniche and Porto, breeding colonies (for a detailed location of each colony see fig. 1 in Lopes et al 2020). Deserta is a sand-barrier island in southern Portugal, with approximately 1400 Yellow-legged Gull breeding pairs.…”

“…Both urban colonies, with unknown population sizes, are close to fishery landing areas. Rooftop nests were commonly constructed in flat areas near structures such as chimneys and walls that would sustain the nests and provide weather protection (Lopes et al 2020). We studied urban nests in two and four different city blocks (i.e.…”