QUANTIFICATION OF TERRESTRIAL HAUL-OUT AND ROOKERY CHARACTERISTICS OF STELLER SEA LIONS

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Abstract

Steller sea lions (Eumetopias jubatus) are known to have occupied the same terrestrial haul-out and rookery sites across the North Pacific Rim for centuries, but it is not known why they choose and stay at these locations, or what defines their preferred habitat. Classifying and comparing the shoreline type of haul-outs and rookeries against sites not used by Steller sea lions showed that they preferentially locate their haul-outs and rookeries on exposed rocky shorelines and wave-cut platforms. However, no preference was found for selecting rookeries on sheltered shore types. Shoreline types used less frequently by sea lions included fine-to-medium-grained sand beaches, mixed sand and gravel beaches, gravel beaches, and sheltered rocky shores. Quantifying the shoreline types used by sea lions confirms anecdotal reports of habitat preferences and may prove useful in identifying and protecting sea lion terrestrial habitat, or in forecasting how climate change might affect the distribution of sea lions.

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