How Do Squirrels Organize Their Hoards?

animals use to conserve energy when food is scarce. Tree squirrels don't need it because they store enough away to keep themselves fed. However, their cousins, the ground squirrels, which have a less bushy tail, burrow underground and are common

in the American West, do hibernate during colder months. Another misconception is that tree squirrels store that food they've collected during the summer and fall, like for example, acorns directly in their nests are dens for easy access during the winter. But the process by which tree squirrels keep themselves fed during the lean months turns out to be way more complex and active than stalking a pantry at home. Researchers

are learning that it suggests some advanced memory skills. A group out of the Department of Psychology at UC Berkeley published a study about this back in twenty seventeen. In it, they lay out how tree squirrels use a mnemonic technique called spatial chunking to sort out and hide their nuts scores by size, type, and perhaps even nutritional value and taste. When they're hungry later, it's theorized they can remember where to find what they want. But let's back up a little.

The tree squirrels are a diverse group of squirrels that live primarily in trees instead of burrowing in the ground. They'll eat pretty much anything seeds, nuts, tree buds, berries, leaves, parts of pine cones, bird eggs, nestlings, and the occasional slice of found pizza. Some of that stuff they eat right away and the rest they well squirrel away for later. But as winter approaches, squirrels are faced with a challenge.

They know instinctively that food sources will soon be scarce, so they gather all the food they'll need for a few months while also keeping themselves fed day to day. That's why they're so busy in the fall, when nuts like acorns have all fallen from their trees. Some squirrels, like red squirrels, tend to hide their food in a single stash, but others are what's known as scatter hoarders,

which means pretty much what it sounds like. They hoard their food and scatter it in several different locations where they can easily access it. That's usually close to the tree holding their nest or done, but they often expand into areas of around seven acres or three hectors. Rather than leaving their goods above ground where other squirrels might steal them, they bury them. This is called caching about an inch under the soil that's around two to three centimeters.

Squirrels are even known to crack open nuts before burying them to prevent them from germinating, though not always and actually squirrels accidentally plant a lot of trees trease. Anyway, when it comes time to eat, they forage for the

nuts they buried. Squirrels do possess a strong sense of smell, which allows them to sniff out nuts from under a blanket of dirt, especially if the squirrels marked its nuts with their own scent, usually from glands on their face, but researchers have long noticed evidence of strategic intelligence in

the placement of their food. For instance, one study in two thousand and eight reported that Eastern gray squirrels engage in deceptive caching, That is, they dig a hole, pretend to throw in an acorn while holding it in their mouth, cover up the empty hole, and then run off to another secret stash place. They do this, it was suggested, to fool other squirrels who might be watching, and the study from twenty seventeen indicates even more complex thinking behind

the caching. In field experiments conducted over nineteen months from twenty twelve to twenty fourteen, researchers fed forty five marked free ranging Eastern fox squirrels one nut at a time, as sixteen total for each squirrel, varying the type of nut almonds, hazelnuts, pecans, and walnuts. If the squirrels didn't eat the nuts right away, the researchers tracked through GPS

where the squirrels subsequently buried their prizes. What they found showed evidence of spatial chunking, meaning that the squirrels put specific nuts in similar places to apparently help them remember which nuts were ware, So for example, a given animal would place almonds in one general area and hazel nuts in another. We can only assume that had pizza been involved, it would have gotten its own location too. This mneumonic

strategy has also been seen in rats. The researchers explained that the strategy could make it easier for squirrels to find not just any stash, but the specific type of stash they're looking for, and use less brain space to do it. For the article this Episodes based on How Stuff Works, spoke via email with Michael A. Steel, a biology professor at Wilkes University in Pennsylvania and the guy

who first described the deceptive cas us mentioned above. He said, I find the results consistent with some of my studies and those of others in which we are learning how involved the scatter hoarding process is for tree squirrels. Squirrels are certainly well adapted to solve foraging and caching problems, well beyond most people's greatest expectations. We know that gray squirrels selectively move more valuable seeds or nuts to sites in the open where predation risks are higher, but pilfridge

risks from other squirrels are lower. This means squirrels cess seed and nut quality and trade off some risk of predation to secure seeds and sights. The twenty seventeen study took into account, among other variables, the sex of the squirrels in the experiment, the order in which the nuts were received by the squirrels, and the weight and nutritional

value of each nut. They appeared to be organizing nuts by size in addition to type, so the next time you see a squirrel digging up a nut, know that she might have found the exact one she was looking for. Today's episode is based on the article squirrels actually organize their net hoard Here's Why on HowStuffWorks dot Com, written by Jamie Allen. Green Stuff is production of by Heart Radio in partnership with how stuffworks dot Com, and it

is produced by Tyler Klang. Four more podcasts from my heart Radio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.