Squirrels organize their favorite nuts by type, UC Berkeley researchers find

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Squirrels may have greater cognitive abilities than their “nutty” diet would indicate, a study published Sept. 13 by UC Berkeley researchers suggests.

The study, authored by campus postdoctoral researcher Mikel Delgado and UC Berkeley psychology professor Lucia Jacobs, found that wild fox squirrels organize their nuts according to variety, using a cognitive method called “chunking.” Chunking is a memorization method in which information is processed in smaller “chunks.”

Squirrels are not the first animals to demonstrate chunking — laboratory rats use spatial chunking when learning a maze and nightingales chunk by syllable to learn long songs, Jacobs explained.

“Back before we had cell phones, people actually had to remember phone numbers,” Delgado said. “We wouldn’t remember a 10-digit string — you’d remember the first three digits, you’d remember the area code (that is) separate … and then you’d have the last four digits at the end.”

The study builds on data that was found about 15 years ago by an undergraduate student under the supervision of Jacobs. The data suggested that there was a correlation between species of nuts and where a squirrel would bury it.

In order to ensure accuracy, Delgado and Jacobs attempted to simulate as many conditions as they possibly could — in some experiments, they would give four nuts of the same kind to squirrels, and in others they would give nuts in a completely randomized order. In almost every case, the squirrels would bury each type of nut in its own designated area.

“They would actually put different nut types in different areas with very little overlap between the species of nuts,” Delgado said. “We thought (randomizing the order) might make it harder to remember … but it didn’t have a major effect on their behavior.”

According to Linda Wilbrecht, a UC Berkeley associate professor of psychology unaffiliated with the study, Delgado and Jacobs’ work is significant because it observed squirrels in their natural habitat instead of in a lab. Wilbrecht said in an email that studying animals can help explain human thinking processes as well.

Jacobs said she is currently in the process of using this study — which she has dubbed the “squirrel password problem” — to petition for a grant from the National Science Foundation.

“It’s just like when you have to remember a password, but you also don’t want the password to be easily guessed,” Jacobs said. “It’s exactly the same situation, so we think that this has very interesting implications when it comes to … how this memory process actually works.”

Jacobs said she has been working with squirrels for 40 years, adding that she has an “intuition” about squirrels that others might not.

“Nothing about squirrels really surprises me anymore,” Delgado said.

Contact Anjali Shrivastava at [email protected] and follow her on Twitter at @anjalii_shrivas.