Recently-adopted foraging strategies constrain early chick development in a coastal breeding gull

• Published in: PeerJ (San Francisco, CA) Vol. 7; p. e7250
• Main Authors: Sotillo, Alejandro, Baert, Jan M, Müller, Wendt, Stienen, Eric W M, Soares, Amadeu M V M, Lens, Luc
• Format: Journal Article
• Language: English
• Published: United States PeerJ. Ltd 10-07-2019; PeerJ, Inc; PeerJ Inc
• Subjects: Animal behavior; Animal reproduction; Anthropogenic food; Biology; Breeding; Breeding success; Coastal ecosystems; Coupled Natural and Human Systems; Diet; Discard ban; Early development; Ecology; Field study; Fish; Fisheries; Fishes; Fishing; Food; Food quality; Food sources; Foraging behavior; Foraging strategies; Gulls; Juveniles; Landfill; Laridae; Marine Biology; Niches; Novels; Opportunistic feeders; Population biology; Population dynamics; Population studies; Reproductive fitness; Retirement benefits; Specialization; Urban environments; Waterfront development; Zoology; Belgium; Scavengers; Anthropogenic food; Discard ban; Gulls; Opportunistic feeders; Foraging strategies; Early development
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.7250

Human-mediated food sources offer possibilities for novel foraging strategies by opportunistic species. Yet, relative costs and benefits of alternative foraging strategies vary with the abundance, accessibility, predictability and nutritional value of anthropogenic food sources. The extent to which such strategies may ultimately alter fitness, can have important consequences for long-term population dynamics. Here, we studied the relationships between parental diet and early development in free-ranging, cross-fostered chicks and in captive-held, hand-raised chicks of Lesser Black-backed Gulls (
) breeding along the Belgian coast. This traditionally marine and intertidal foraging species is now increasingly taking advantage of human activities by foraging on terrestrial food sources in agricultural and urban environments. In accordance with such behavior, the proportion of terrestrial food in the diet of free-ranging chicks ranged between 4% and 80%, and consistent stable isotope signatures between age classes indicated that this variation was mainly due to between-parent variation in feeding strategies. A stronger terrestrial food signature in free-ranging chicks corresponded with slower chick development. However, no consistent differences in chick development were found when contrasting terrestrial and marine diets were provided
to hand-raised chicks. Results of this study hence suggest that terrestrial diets may lower reproductive success due to limitations in food quantity, rather than quality. Recent foraging niche expansion toward terrestrial resources may thus constitute a suboptimal alternative strategy to marine foraging for breeding Lesser Black-backed Gulls during the chick-rearing period.