McHuron E A, Robinson P W, Simmons S E, Kuhn C E, Fowler M, Costa D P
Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, 95064, USA.
Marine Mammal Commission, Bethesda, MD, 20814, USA.
Oecologia. 2016 Dec;182(4):995-1005. doi: 10.1007/s00442-016-3732-0. Epub 2016 Sep 20.
Intraspecific variability is increasingly recognized as an important component of foraging behavior that can have implications for both population and community dynamics. We used an individual-level approach to describe the foraging behavior of an abundant, generalist predator that inhabits a dynamic marine ecosystem, focusing specifically on the different foraging strategies used by individuals in the same demographic group. We collected data on movements and diving behavior of adult female California sea lions (Zalophus californianus) across multiple foraging trips to sea. Sea lions (n = 35) used one of three foraging strategies that primarily differed in their oceanic zone and dive depth: a shallow, epipelagic strategy, a mixed epipelagic/benthic strategy, and a deep-diving strategy. Individuals varied in their degree of fidelity to a given strategy, with 66 % of sea lions using only one strategy on all or most of their foraging trips across the two-month tracking period. All foraging strategies were present in each of the sampling years, but there were inter-annual differences in the population-level importance of each strategy that may reflect changes in prey availability. Deep-diving sea lions traveled shorter distances and spent a greater proportion of time at the rookery than sea lions using the other two strategies, which may have energetic and reproductive implications. These results highlight the importance of an individual-based approach in describing the foraging behavior of female California sea lions and understanding how they respond to the seasonal and annual changes in prey availability that characterize the California Current System.
种内变异性日益被视为觅食行为的一个重要组成部分，这可能对种群和群落动态产生影响。我们采用个体层面的方法来描述一种丰富的、广食性捕食者的觅食行为，这种捕食者栖息在一个动态的海洋生态系统中，特别关注同一人口统计学群体中个体所采用的不同觅食策略。我们收集了成年雌性加利福尼亚海狮（Zalophus californianus）在多次出海觅食行程中的运动和潜水行为数据。海狮（n = 35）采用了三种觅食策略之一，这些策略主要在海洋区域和潜水深度上有所不同：浅表层策略、表层/底层混合策略和深潜策略。个体对给定策略的忠诚度各不相同，在为期两个月的跟踪期内，66%的海狮在所有或大部分觅食行程中只使用一种策略。在每个采样年份中都存在所有的觅食策略，但每种策略在种群层面的重要性存在年际差异，这可能反映了猎物可获得性的变化。与采用其他两种策略的海狮相比，深潜海狮的行程较短，在繁殖地花费的时间比例更大，这可能对能量和繁殖有影响。这些结果凸显了基于个体的方法在描述雌性加利福尼亚海狮觅食行为以及理解它们如何应对加利福尼亚洋流系统中猎物可获得性的季节性和年度变化方面的重要性。
