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

NORA LISNIZER; ALEJANDRO GATTO; PABLO YORIO

evento modo virtual

Congreso; World Seabird Twitter Conference 6; 2020

World Seabird Union

We studied trophic niche variation throughout the year2012 in Kelp Gulls Larus dominicanusfrom two colonies in Patagonia, Argentina, located in areas with different availabilityof anthropogenic food subsidies (open-air refuse dumps and fisheries discards).We used stable isotope analysis (δ15N, δ13C) of blood andprimary feathers to obtain isotopic niche width (multivariate ellipse-basedmetrics). Niche width was wider at both colonies during the non-breedingseason, suggesting that during this period gulls forage on a greater variety offood sources. Individuals from the colony with availability of fisheriesdiscards presented the lower isotopic niche width year-round. Anabrupt expansion in niche width occurred later in the non-breeding season,after the start of a fisheries moratorium, suggesting that Kelp Gulls remainedin nearby areas and partly associated to trawl fisheries between breedingevents. Results suggest that the availability of discards cangreatly influence Kelp Gull foraging strategies andnon-breeding movements.