Anthropogenic food subsidies shape parental foraging and offspring development in an opportunistic bird
Abstract
Humans are transforming ecosystems by providing predictable anthropogenic food subsidies (PAFS), such as at landfills, now used by multiple animal taxa. In breeding animals, parental landfill use can influence offspring development, yet few studies have quantified parental landfill use and linked it to parental care and offspring development, behaviour or survival, limiting our understanding of the population-level consequences of PAFS use. Between 2021-2024, we GPS-tracked 56 adult and 79 juvenile Yellow-legged gulls (Larus michahellis) across five Mediterranean colonies. We also analysed the content of 373 pellets and the growth of 257 nestlings until fledging. Our aim here was to understand whether (i) PAFS use, particularly landfills, by breeding adults differed among colonies; (ii) landfill use affected parental foraging trips and plastic consumption; (iii) parental landfill use influenced chick growth and condition; and (iv) this affected post-fledging movements and survival of juveniles. We found that adult landfill use varied among colonies, independently of the distance to the nearest landfills. Higher landfill use resulted in fewer and shorter foraging trips during chick rearing and increased consumption of anthropogenic materials. Chicks from high-use colonies developed and fledged in poorer body condition, which delayed the onset (but not the distance) of dispersal movements, without affecting post-fledging survival. Our results reveal a potential trade-off in PAFS use, which may act as a time-saving foraging strategy for parents while compromising offspring body condition. This demonstrates how anthropogenic subsidies can shape the behaviour of breeding animals and generate carry-over effects on offspring development and early-life behaviour.
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BibTeX
@misc{acacio2026anthropogenic,
title = {{Anthropogenic food subsidies shape parental foraging and offspring development in an opportunistic bird}},
author = {Marta Acácio and Charly Souc and Carole Leray and Thomas Blanchon and Florence Nono Almeida and Raül Ramos and Jean-Baptiste Lanfranchi and Marion Vittecoq and Karen D. McCoy},
howpublished = {EcoEvoRxiv},
year = {2026},
month = oct,
doi = {10.32942/x21982},
url = {https://ecoevorxiv.org/repository/view/15473/},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Anthropogenic food subsidies shape parental foraging and offspring development in an opportunistic bird
AU - Marta Acácio
AU - Charly Souc
AU - Carole Leray
AU - Thomas Blanchon
AU - Florence Nono Almeida
AU - Raül Ramos
AU - Jean-Baptiste Lanfranchi
AU - Marion Vittecoq
AU - Karen D. McCoy
PY - 2026
DA - 2026/10/12
PB - EcoEvoRxiv
DO - 10.32942/x21982
UR - https://ecoevorxiv.org/repository/view/15473/
AB - Humans are transforming ecosystems by providing predictable anthropogenic food subsidies (PAFS), such as at landfills, now used by multiple animal taxa. In breeding animals, parental landfill use can influence offspring development, yet few studies have quantified parental landfill use and linked it to parental care and offspring development, behaviour or survival, limiting our understanding of the population-level consequences of PAFS use. Between 2021-2024, we GPS-tracked 56 adult and 79 juvenile Yellow-legged gulls (Larus michahellis) across five Mediterranean colonies. We also analysed the content of 373 pellets and the growth of 257 nestlings until fledging. Our aim here was to understand whether (i) PAFS use, particularly landfills, by breeding adults differed among colonies; (ii) landfill use affected parental foraging trips and plastic consumption; (iii) parental landfill use influenced chick growth and condition; and (iv) this affected post-fledging movements and survival of juveniles. We found that adult landfill use varied among colonies, independently of the distance to the nearest landfills. Higher landfill use resulted in fewer and shorter foraging trips during chick rearing and increased consumption of anthropogenic materials. Chicks from high-use colonies developed and fledged in poorer body condition, which delayed the onset (but not the distance) of dispersal movements, without affecting post-fledging survival. Our results reveal a potential trade-off in PAFS use, which may act as a time-saving foraging strategy for parents while compromising offspring body condition. This demonstrates how anthropogenic subsidies can shape the behaviour of breeding animals and generate carry-over effects on offspring development and early-life behaviour.
ER -