How forests benefit from grey squirrels who forget where they put their nuts

October 7, 2014, 1 p.m.

An imperfect memory saves forests

Rob Swihart, a wildlife ecologist at Purdue University, researched the habits of grey squirrels as they collect nuts and store them for winter food. Because grey squirrels compete with many other animals for the same food source, they tend to bury nuts in many, many secret stashes all over their forest habitat. They can't always get back to spots where they've buried their nuts, either because they forgot where they are or perhaps they've become a meal for another forest animal. That forgotten stash often ends up sprouting into new nut-bearing trees which benefit many animals in the ecosystem.

This is more beneficial to deciduous forests than the habits of red squirrels, which stash their winter food all in one pile. The habit works fine when red squirrels are foraging in evergreen forests and collecting pine cones, the seeds of which can survive fine in these large piles. But when red squirrels are foraging in deciduous forests and storing nuts in these same large piles, the nuts tend to dry out and die. They can't sprout into new trees, which means fewer nut-bearing trees and less diverse and healthy forests.

Even though the fallibility of grey squirrels' memories is beneficial to forests, the fact that they remember as much as they do is astounding. According to research published in Princeton University's journal "Animal Behavior," grey squirrels can remember not only where they buried their caches but also how much is in them. A study showed that squirrels will return first to the caches with the larger amounts of food.

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