Age-related feeding behaviour and foraging efficiency in Kelp Gulls Larus dominicanus attending coastal trawlers in Argentina

Authors
Bertellotti, Néstor Marcelo; Yorio, Pablo Martin
Publication Year
2000
Language
English
Format
article
Status
Published version
Description
We studied age-related differences in feeding behaviour and foraging success of Kelp Gulls Larus dominicanus feeding on fishery discards at trawl vessels in northern Patagonia, Argentina. Kelp Gulls consumed fish by direct capture and intraspecific kleptoparasitism. Direct capture rate increased significantly with age. Juveniles dropped a higher proportion of handled fish than older birds. Intraspecific kleptoparasitism involved gulls of all age-classes and was recorded in all hauls. The percentage of successful attempts was similar among different age-classes. However, juveniles and immatures attempted to steal prey more frequently and therefore obtained more prey than expected. The proportion in which each feeding method (direct capture and kleptoparasitism) contributed to overall fish consumption varied significantly among age-classes. Juveniles obtained most of the food through kleptoparasitism (72%), while immature, subadult and adults consumed prey mostly through direct capture (77, 91 and 92%, respectively). Using both feeding methods, Kelp Gulls swallowed 87.6% of the discarded fish that they handled. However the percentage of fish swallowed over total handled fish were different among age-classes (juveniles: 45.5%; immatures: 70.8%; subadults: 83.3%; adults: 94.8%). Kleptoparasitism may be used as an alternative strategy to compensate the lower efficiency of young birds.
Fil: Bertellotti, Néstor Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; España. Universidad Nacional de la Patagonia; Argentina
Fil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina. Wildelife Conservation Society; Estados Unidos
Subject
Larus dominicanus
Age-related feeding eficienty
Fishery waste
Scavenging
Kleptoparasitism
Otras Ciencias Biológicas
Ciencias Biológicas
CIENCIAS NATURALES Y EXACTAS
Access level
Restricted access
License
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repository
CONICET Digital (CONICET)
Institution
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identifier
oai:ri.conicet.gov.ar:11336/70652