Individual consistencies in search behaviour of breeding Imperial Cormorants (Phalacrocorax atriceps) at Punta León, Argentina

HARRIS S; RAYA REY A; QUINTANA F

Plymouth

Conferencia; 11th International Conference Seabird Group.; 2011

The few studies to date indicate that foraging behaviour on successive trips taken by individual seabirds is more consistent than would be expected if they represented random samples from a given population. Individual consistencies could result from prey specialization or limited variation in the surrounding environment over short temporal scales, as well as the forager?s sex, age, life history and current physiological and behavioural restrictions. Behavioural consistency has been linked to time elapsed between events, being stronger at shorter time intervals. During the 2009 breeding season at the Punta León colony (64° 29.75 W;43° 04.6 S), twenty-two breeding Imperial Cormorants (Phalacrocorax atriceps) (twelve females and ten males) were equipped with mini GPS loggers to record their position (at 1 Hz) during two foraging trips on consecutive days. Thirteen of these individuals (seven females and six males) were fitted with loggers during a second period, twelve days later, again for two consecutive foraging trips. Several parameters were extracted from the foraging trips to evaluate individual consistency. On consecutive days, there was a high degree of similarity in the trips of individual females in terms of the maximum distances from the colony and shore, sinuosity, and area covered relative to the maximum distance reached. In contrast, although individual males showed similar trip durations on consecutive days, in general they tended to increase the maximum distance reached from the colony and the shore as well as the percentage of time flying on the second day. In addition, females tended to be more consistent than males in most foraging trip parameters during the second series of deployments. However, considerable behavioural variability between individuals was detected for both sexes. An increase in food demand by the growing offspring, as well as changes in the environment as the season progresses, may have different impacts on females compared with males, potentially exerting greater pressure on females to optimize their behaviour or providing them with less flexibility than males in terms of foraging opportunities.