Millions of trees are accidentally planted by squirrels that bury nuts and then forget where they hid them.

Squirrels forget where about 50% of the nuts they’ve hidden are

“How squirrels change a forest. I’m Bob Hirshon and this is Science Update.

Squirrels collect and store nuts so they’ll have food to last through winter. That thriftiness benefits more than just the squirrel—it helps the trees, too. That’s according to Rob Swihart, a wildlife ecologist at Purdue University.

Swihart:
Nuts clearly are dependent on either gravity or animals for dispersal. Squirrels are one of the most important species in this regard.

But not all squirrels provide this service. Swihart and his colleagues have found that gray squirrels bury nuts all over the place, and often forget them. That results in trees growing in new areas.

But red squirrels store nuts in piles on the ground. Those piled-up nuts tend to dry out and don’t take root. And because red squirrels adapt better to changes in the landscape, Swihart says the squirrel population might be shifting toward that species.

Swihart:
We are predicting that that will have a significant impact on the nut-producing trees that depend on—at least to a fair extent—gray squirrels for dispersing their offspring.

As a result, forests of oak, walnut, and other hardwoods could shrink, because of the nut-gathering strategy of the wrong kind of squirrel. I’m Bob Hirshon for AAAS, the Science Society.”

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