Nature’s ingenious strategists

I was recently asked by a local TV news station to answer a question about how squirrels find their buried nuts.

This is a great example of super cool things that go on in nature that most people don’t understand or realize.

So, let’s look at these amazing squirrels and their incredible ability to bury nuts and find them later.

The eastern gray squirrel (Sciurus carolinensis) is a large tree-dwelling squirrel found in North America. It is native to the eastern half of the country, with several similar species inhabiting the western half. Eastern gray squirrels display a wide variety of colors, ranging from pure white (albino) and partial white (leucistic) to all black (melanistic) and auburn (rusty brown). However, they are primarily gray.

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But it’s the squirrel’s ability to bury nuts, and more importantly, how they find them later, that is so interesting.

First, eastern gray squirrels can’t put on enough fat to last them all winter, so hibernating like other squirrels isn’t an option. They need to have access to food all winter. So, storing winter food starts in summer when the oak, hickory and walnut trees are dropping their nuts.

Squirrels are considered scatter hoarders, which means instead of storing all their winter food supply in one place, like chipmunks, they scatter their food around in many places. This is a great strategy to prevent losing everything if another squirrel, raccoon, or skunk raids their stash of food. 

Each nut the squirrel finds in summer and fall is given a full examination. They roll the nut around and around in their front paws feeling for the shell’s integrity. They inspect it for cracks and holes in the shell. They also sniff/smell the nut, checking to see if it is rotten or spoiled. Once it passes these quality control tests the squirrel decides if it will eat the nut now or save it for later.

If they determine that they want to save it for later, they move away from the site where they found it and look for a place to bury the nut. Usually, they dig a shallow hole with their front paws and then push the nut down into the soil. However, if they feel like another squirrel is watching, they will pretend to bury the nut, going through all the motions of concealing it but won’t actually do it. They scamper off until they feel no other squirrel is watching and then bury it.

Each squirrel buries thousands of nuts every year in preparation for winter. Squirrels are crucial when it comes to planting new trees away from the parent trees and expanding the forest.

So, does that mean that they don’t find the nuts they buried in preparation for winter? No, it doesn’t. Studies with captive squirrels show they find upwards of 90 percent of the nuts they have stored for later. That means 10 percent of the nuts are not found and are allowed to sprout into new trees.

So, just how does a squirrel find the nuts it buried weeks or months before?

A couple of fun studies show that the squirrels use a spatial map in their mind to remember where they placed the nuts. In other words, they use landmarks such as large rocks, prominent trees or other objects to help guide them back to the area where they buried the nuts. Once they are in the general vicinity, they use their sense of smell to find the exact location of the buried food supply.

They proved this by allowing captive squirrels to bury nuts in an area with large rocks and logs. Then, they removed the squirrels from the area. Once the squirrels were away, they shifted all the large objects the same distance and same direction in the area where the nuts were buried. Later when the squirrels were brought back the squirrels looked for the buried nuts but were off by the same distance and direction that the objects were moved.

I guess the point is, if your life depended upon successfully hiding and then later finding the food source that will keep you alive, you would develop a very accurate way to both hide and relocate that food. Now refine that system over many tens of thousands of years and you have the answer to how squirrels find the nuts they bury. Until Next time …

Editor’s note: Stan Tekiela’s NatureSmart column makes its debut on the Eden Prairie Local News (EPLN) website. Starting this month, you can look forward to reading his column twice a month on EPLN. Previously, it was a long-standing feature in the Eden Prairie News. In addition to his column, Tekiela serves as the director/supervisor at the Eden Prairie Outdoor Center.

Tekiela is an author, naturalist, and wildlife photographer who travels extensively across the United States to study and capture wildlife images. You can follow his work on Instagram and Facebook. He can be contacted via his website at www.naturesmart.com.