Trophic niche variation throughout the year in the opportunistic Kelp Gull in different context of anthropogenic food subsidies in Patagonia, Argentina

LISNIZER, NORA; GATTO, ALEJANDRO; YORIO, PABLO

Congreso; 6th World Seabird Twitter Conference; 2020

World Seabird Union

We studied trophic niche variation throughout the year 2012 in Kelp Gulls Larusdominicanus from three colonies in Patagonia, Argentina, located in areas withdifferent availability of anthropogenic food subsidies. We used stable isotope analysis(δ15N, δ13C) of blood and primary feathers to obtain isotopic niche width(multivariate ellipse-based metrics). Niche width was wider at all colonies during thenon-breeding season, suggesting that during this period gulls forage on a greatervariety of food sources. Individuals from the colony with year-round availability offisheries discards presented the lower isotopic niche width year-round compared tothose from the other two colonies, one with discards only available during thebreeding season and the other with only open-air refuse dumps available all year-round. These results suggest that the availability of discards can greatly influence KelpGull foraging strategies and that changes in niche metrics can be context dependent.