The role of body size in individual-based foraging strategies of a top marine predator

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Weise, M. J., Harvey, J. T., & Costa, D. P. (2010). The role of body size in individual-based foraging strategies of a top marine predator. Ecology, 91(4), 1004-1015. doi:10.1890/08-1554.1
TitleThe role of body size in individual-based foraging strategies of a top marine predator
AuthorsM. Weise, J. Harvey, D. Costa
AbstractBody size is an important determinant of the diving and foraging ability in airbreathing marine vertebrate predators. Satellite-linked dive recorders were used during 20032004 to investigate the foraging behavior of 22 male California sea lions (Zalophus californianus, a large, sexually dimorphic otariid) and to evaluate the extent to which body size explained variation among individuals and foraging strategies. Multivariate analyses were used to reduce the number of behavioral variables used to characterize foraging strategies (principal component analysis, PCA), to identify individually based foraging strategies in multidimensional space (hierarchical cluster analysis), and to classify each individual into a cluster or foraging strategy (discriminant analysis). Approximately 81.1% of the variation in diving behavior among individuals was explained by three factors: diving patterns (PC1), foraging effort (PC2), and behavior at the surface (PC3). Individuals were classified into three distinct groups based on their diving behavior (shallow, mixed depth, and deeper divers), and jackknife resampling of the data resulted in correct group assignment 86% of the time. Body size as an independent variable was positively related to dive duration and time spent ashore and negatively related to time at sea, and it was a key parameter in PC2 used to classify the three distinct clusters. Differences among individual-based foraging strategies probably were driven by differences in body size, which enabled larger animals to dive deeper and forage more efficiently by targeting different and perhaps larger prey items. The occurrence of foraging specializations within a species and age class has implications for quantitative modeling of population-level predator-prey interactions and ecosystem structure. © 2010 by the Ecological Society of America.
Start page1004
End page1015
Subjectsbody size, cluster analysis, ecosystem structure, foraging behavior, marine ecosystem, pinniped, predator, predator-prey interaction, principal component analysis, satellite data, sexual dimorphism, animal, article, feeding behavior, male, physiology, seal, Animals, Sea Lions, Animalia, Otariidae, Vertebrata, Zalophus, Zalophus californianus
NoteCited By (since 1996):17, Marine Mammals, Birds & Turtles, CODEN: ECOLA