Study Finds Fox Squirrels Organize Their Nut Storage Caches by Variety and Quality

Posted on October 16, 2017

UC Berkeley researchers spent two years observing how fox squirrels store their nuts. They found squirrels organize their nuts by variety, quality and possibly even preference. The study is the first to show squirrels use a cognitive strategy called "chunking." Chunking refers to organizing objects or information into smaller more manageable collections or chunks. Using subfolders on a computer is a type of chunking.

The researchers say fox squirrels stockpile 3,000 to 10,000 nuts per year. They separate each cache into quasi "subfoloders," with one cache for each type of nut. For example, the squirrels stored almonds in a separate area from walnuts. This strategy makes it easier for the squirrels to remember where their favorite nuts are. Having multiple piles may also prevent all of a squirrels nuts from being taken at once if a single stockpile is discovered or destroyed.

Mikel Delgado, a post-doctoral researcher is the lead author of the study published in Royal Society Open Science. He conducted the research with UC Berkeley psychology professor Lucia Jacobs. Delgado says, "This is the first demonstration of chunking in a scatter-hoarding animal, and also suggests that squirrels use flexible strategies to store food depending on how they acquire food."

Jacobs says, "Squirrels may use chunking the same way you put away your groceries. You might put fruit on one shelf and vegetables on another. Then, when you’re looking for an onion, you only have to look in one place, not every shelf in the kitchen."

Here's a video of a squirrel caching nuts.

Image: Amber Engle

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