Kelp gull population trends in northern Patagonia, Argentina: a regional perspective considering artificial food sources

LISNIZER, NORA; GARCÍA BORBOROGLU, PABLO; YORIO, PABLO

Victoria

Congreso; 1st World Seabird Congress; 2010

Birdlife International

Food availability is a key factor influencing seabird population dynamics. The Kelp gull Larus dominicanus is widely distributed in the Southern Hemisphere, including the Atlantic coast of Argentina. It is a generalist species that feeds on a wide variety of food from natural and artificial sources. We analyzed Kelp gull population trends at 71 colonies in northern Patagonia, Argentina (1800 km of coastline, from 40°47’ to 46°00’S), considering the relationship of colonies with artificial food sources (fisheries discards and landfills). We used recent census of breeding pairs (2006-2008) integrated with unpublished and published information, extending over a 15-year period (1994-2008). We analyzed the population trend for the whole study area and then for the same set of colonies divided into four coastal sectors characterized by differences in the characteristics of artificial food sources. We tested for differences in population growth rates among sectors by fitting linear regression models and comparing regression slopes. The Kelp gull population in the study area increased 52%, from 47500 to 72000 breeding pairs (λ=1.027). Population growth rates showed significant differences (p