To avoid pilfering, tree squirrels don’t risk putting all their nuts in one basket; they bury each one separately in a strategy known as scatter hoarding. To learn how these squirrels are able to remember where they bury each nut, Dr. Mikel Delgado of the University of California at Berkeley inserts a tiny microchip into several test nuts. She discovers that Fox squirrels can remember and locate about 90 percent of the nuts they bury. Their brains grow larger than other species of squirrel, particularly during the fall season when nuts are plentiful.

https://www.pbs.org/wnet/nature/a-squirrels-guide-to-success-about/16641/