Factors affecting individual foraging behavior in a threatened seabird: Olrog's Gull (Larus atlanticus) as a case study

ZUMPANO FRANCISCO; CASTANO MELINA; FAVERO MARCO; GARCÍA GERMÁN OSCAR

CANADIAN JOURNAL OF ZOOLOGY

NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS

Lugar: Otawa; Año: 2021

0008-4301

The analysis of feeding strategies in animals is one of the most important topics in foraging ecology. The individual´s foraging behavior depends on both the individual?s own actions and the behavior of other foragers. Here we analyse the effect of the sex and group size on the foraging behavior of immature Olrog´s Gull (Larus atlanticus Olrog, 1958), endemic to the Atlantic coast of southern South America and regionally listed a threatened species. Birds were captured, banded, sexed and aged during the non-breeding season in Mar Chiquita coastal lagoon, Argentina. The foraging behavior was quantified by observations made on individuals of known identity, recording the size of foraging groups, as well as prey size and type. Foraging parameters estimated were foraging effort, capture rate and foraging efficiency. Males spent more time in agonistic behavior and captured larger prey. With an increase of group size, the capture rate, the capture of small crabs in males, and foraging effort were higher. The agonistic behaviors, size of consumed prey and foraging effort were affected by individual identity. Our study pinpoints factors underlying variation in the foraging behavior of Olrog?s Gulls and illustrates the importance of modelling individual variation when analyzing foraging behavior.