Ingestion of anthropogenic materials by yellow-legged gulls (Larus michahellis) in natural, urban, and landfill sites along Portugal in relation to diet composition

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

“…These values are relatively similar to those of other gull debris studies using necropsies (review by Seif et al, 2018). In previous studies, both YLG and LBBG exhibited high levels of anthropogenic materials in their pellets (Alonso et al, 2015;Calado et al, 2018), especially in urban and landfill environments (Lopes et al, 2021). However, the use of necropsies only allows for the detection of a smaller amount of debris in gulls' digestive system (Basto et al, 2019;Codina-García et al, 2013; this study) since gulls have the ability to regurgitate a large part of non-edible food remnants, including anthropogenic materials (Barrett et al, 2007), reducing the time that these materials are in individuals' digestive system.…”

“…Both YLG and LBBG, adults and immatures, males and females, are known to benefit from reliable and predictable food sources, either by interacting with fishing boats and feeding on marine species with higher nutritional value (i.e. fishery discards; Calado et al, 2018Calado et al, , 2021Mendes et al, 2018), mainly in natural habitats, or by feeding on human meal leftovers collected from trash containers or in nearby landfills, in urban habitats (Lopes et al, 2021;Pais de Faria et al, 2021a;Spelt et al, 2019). Also, in this study, we compared FA composition between adults and immature gulls (1-3 years), and we did not consider fledglings.…”

“…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).…”

“…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). In addition to these physical impacts, a range of less visible toxicological effects may be caused by the ingestion of anthropogenic materials, including a possible exposure to hazardous chemicals, especially from plastics containing known or suspected endocrine disrupting chemicals as additives (Gallo et al, 2018) which might contribute to neurological, endocrine and reproductive complications, and ultimately to death (Bouland et al, 2012;Rochman et al, 2016).…”

“…This resulted in an increase of their urban population numbers over the last few years (Duhem et al, 2008;Nager and O'Hanlon, 2016;Vidal et al, 1998). Foraging gulls are known to ingest anthropogenic materials when foraging at their natural habitats (review by Battisti et al, 2019) and at urban areas and landfills (Lopes et al, 2021). Yet, possible invisible physiological effects that may arise from ingesting those materials are poorly known as it may not result in birds' death but in a poorer health condition, possibly only detectable at molecular and cellular organization levels (Lavers et al, 2019;Roman et al, 2019).…”