Where Did I Put That Acorn?

Have you ever wondered how squirrels find the nuts they hid months before?

A typical squirrel can store 3,000 of them in a fall season, in dozens of locations. It seems almost impossible that they could remember them. But they do.

There are 200 species of ground squirrel, tree squirrel and flying squirrel that rely on stored seeds and nuts.

To do that, they need to return to them even after leaves fall and snow covers the ground. How do they do it?

Smell plays a role. But sight and memory are more important.

Squirrels build a mental map of their surroundings: a tree trunk, a large rock, a fallen log, a fence post.

Then they remember the changing spatial relationships between those landmarks when viewed from their different food hiding places.

Some scientists have wondered if a squirrel’s brain grows to meet the season’s mental demands.

Because there are other rodents -- shrews, European moles and weasels – whose brains contract 10% in winter when food is scarce, then expand again in spring, with no impact on function.

But most research suggests a squirrel’s heightened spatial memory is linked to its larger than normal hippocampus, a part of the brain involved in learning and navigation.

They’ve also shown more neuron growth, and less age-related mental decline.

To fuel this acuity, squirrels require a lot of calories – which ironically means they must hide more nuts to help them find the others!