Sea otter study reveals striking variability in diets and feeding ...( SANTA CRUZ CA--Ecologists have long ...)

SANTA CRUZ, CA--Ecologists have long observed that when food becomes scarce, animal populations exploit a wider range of food sources. So scientists studying southern sea otters at different sites in California's coastal waters were not surprised to find that the dietary diversity of the population is higher where food is limited. But this diversity was not reflected in the diets of individual sea otters, which instead showed dietary specialization in response to limited food.

The new findings by researchers at the University of California, Santa Cruz, will be published online in the Proceedings of the National Academy of Sciences the week of January 14. The study found that all sea otters in an area with abundant food resources share the same dietary preferences. Where food is limited, however, a diverse array of feeding strategies emerges, with individual sea otters specializing on particular types of prey.

Tim Tinker, a UCSC research biologist and first author of the paper, said the study has both theoretical implications for the science of ecology and practical implications for wildlife management.

"The traditional way of viewing the relationships between predators and prey and how food webs are structured may be oversimplified," Tinker said. "When you look at the population as a whole, you may see a diversification of the diet in response to limited food resources. But when you look at individuals, you see dietary specialization."

One implication of this dietary specialization for California sea otters is that some otters may be exposed to certain food-borne pathogens much more frequently than otters with different diets. "A lot of sea otters in the Central Coast population are dying from infectious diseases, and this could help us to better understand that disease mortality by allowing us to pinpoint the specific vectors of disease transmission," Tinker said.

Tinker's coauthors on the paper are Gena Bental
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