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Midden

Eastern Gray And American Red Squirrel Food Caching Strategies

Red and Gray Squirrels both store food for the winter, but their food caching strategies are very different. Gray Squirrels store many hickory, oak and beech nuts by engaging in “scatterhoarding” – burying one nut at a time, each in a different spot.  Most popular are acorns, which fall into two groups — those grown by white oak species , and those from the group of red oaks. The acorns of red oaks have delayed germination, making them ideal for storage through the winter.  Those of white oaks germinate sooner, in the fall, so are more readily eaten than buried.  (If a Gray Squirrel chooses to bury an acorn from one of the white oaks, it often removes the embryo before doing so, which kills the seed and prevents germination.)  

Red Squirrels, on the other hand, practice “larderhoarding” –  collecting green cones in the fall (up to 15,000 or more) and storing them in one place (generally in the middle of their territory) where they are fiercely protected. A large pile (midden) can result, under which new cones are placed. This cool, moist environment keeps the cones sealed, protecting the seeds from being eaten by mammals and insects that are unable to open the cones.  Middens can contain enough food to last one to two seasons. (Photo: Exceptionally large Red Squirrel midden submitted by Steve Bird of the Coastal Mountains Land Trust, Belfast, Maine)

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Red Squirrels Dining on Black Walnuts

1-4-15 black walnut 145The method in which a nut has been opened depends on both the species of nut as well as the species of animal that opened it. To complicate things further, it can be difficult to ascertain who opened a nut as a given species, such as the Red Squirrel, often has more than one way of opening a nut. However, a given squirrel usually chooses one way to open a nut and consistently uses that method, so that if you come upon a pile, or midden, of nuts eaten by a Red Squirrel, the nuts will most likely all have been opened in the same way.

The beveled edges on the hole in the pictured Black Walnut, the fact that it was opened from both sides (leaving the dividing rib between the two sides intact), and the central location of the holes are indications that a Red Squirrel dined on the nutmeat. The chewing of open, jagged holes on either side of a nut is a Red Squirrel’s most common method of opening a nut. Gray Squirrels tend to remove the entire side of a walnut, as opposed to chewing a hole in it.

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