Spatial and temporal patterns in the diet of the Kelp Gull in Patagonia

The Kelp Gull (Larus dominicanus) is an abundant and widely distributed spe cies in coastal Patagonia, and has increased in number at many locations du ring the last decade. We present comparative information on diet compositio n between locations and diet variation throughout the breeding cycle at thr ee Provincial Wildlife Reserves (Punta Piramide, Punta Leon, and Punta Tomb o), Chubut, Patagonia. We analyzed diet using regurgitated pellets. A total of 41 types of prey were identified at the three colonies. Kelp Gulls fed throughout the season mostly on intertidal invertebrates, although fish als o was an important diet component, mainly during the chick stage. The diet also included garbage, insects, and other seabird offspring. Of all types o f prey, 70.7% were common to the three locations, although the pattern of c onsumption of the main food categories differed among locations. The averag e consumption of garbage differed significantly among locations, with large r amounts of garbage in the diet the closer the colony to the nearest landf ill. Kelp Gulls showed a marked seasonal variation in the consumption of th e main food types. At Punta Tombo and Punta Leon, there was a change from a mostly marine invertebrate diet during the pre-laying and incubation stage s to a mainly fish diet during the chick stage. The consumption of the main food categories was significantly different between seasons at Punta Piram ide but was similar at the other two colonies.