It’s officially fall! Which means, of course, that winter is right around the corner.
This has gotten me thinking about what animals need to do in order to survive the winter. Some, like many birds, migrate to warmer climates; but those animals who don’t migrate must figure out how to deal with the snow and the cold. One option is to just sleep through the winter and hibernate. Another option is to simply suck it up and deal with the cold weather.
This is where squirrels come in. As many of you probably know, squirrels bury food to get them through the winter. In honor of fall and all the squirrels that are busy gathering up nuts for their winter cache, I want to talk today about the Eurasian red squirrel (Sciurus vulgaris).
American vs Eurasian
Now, Eurasian red squirrels shouldn’t be confused with American red squirrels. They are two different species with multiple differences. For one, American red squirrels live in North America, while Eurasian red squirrels live in Europe and Northern Asia (don’t you love it when naming conventions make sense?).
Another difference between the two species is easy to spot: Eurasian red squirrels have noticeable (and super cute) fur tufts on the tips of their ears, while American red squirrels do not.
The two species also vary in how they store food for the winter. While Eurasian red squirrels make multiple food caches (more on that later), the American red squirrel makes a single massive central stash of food called a midden. American red squirrels will fiercely defend their midden and tend to be more territorial in general than Eurasian red squirrels.
Not always red
Although many of them do have red fur, Eurasian red squirrels can come in a variety of colors, including brown, gray, and black. There seems to be some regional variation in the typical color of these squirrels: for instance, there are only red-furred squirrels in the United Kingdom.
Their fur can also change slightly over the seasons. Eurasian red squirrels molt twice a year. They have a thinner summer coat that switches to a darker, thicker winter coat between August and November. They also grow thicker foot fur to protect against the winter cold!
Making your cache
The media was right on this one: red squirrels do indeed mostly eat seeds and nuts from trees. They will also eat berries and shoots when available. Like many rodents, they are opportunistic carnivores and will eat bird eggs or chicks if the opportunity arises.
As I alluded to earlier, red squirrels do not hibernate for the winter. Instead, they survive on all the food they have hidden, or cached, during the spring, summer, and fall. The Eurasian red squirrel stores their food in multiple caches throughout their territory. During the winter, they simply must remember where they buried their food and retrieve it.
Are they good at remembering where their food is? Eh, kinda. To be fair, Eurasian red squirrels remember the location of their cache at a better-than-chance level. This suggests that they do have some decent memory of where their food is buried. However, their spatial memory is considerably less accurate and less durable than the memory of gray squirrels. As a result, many caches are never found.
(On the plus side, though, this means that the seeds have a chance to grow into new trees!)
Under pressure
Unfortunately, Eurasian red squirrels are declining in Britain and Italy because of an invasive species: the Eastern gray squirrel. This is the gray squirrel we have in North America; they were introduced into Europe as an ornamental species in the 1870s and are outcompeting the Eurasian red squirrels.
How? There are a few reasons that stack the odds in the gray squirrel’s favor.
First, gray squirrels are carriers of a Parapoxvirus. This disease doesn’t appear to affect the health of the gray squirrel carriers, but it is deadly for Eurasian red squirrels.
In addition, gray squirrels seem to be better at digesting green acorns than Eurasian red squirrels are. This means that they are more likely to eat said green acorns, drastically decreasing the number of ripe acorns Eurasian red squirrels have access to later in the season.
Finally, Eurasian red squirrels simply don’t breed as much when they are under pressure. It’s hard to think about having kids when there’s less food and a deadly disease going around.
The good news is that the Eurasian red squirrels seem to be fighting back. In England, there seems to be growing numbers of Eurasian red squirrels, and there are plans for humans to continue to help increase their population.
There is also talk of reintroducing a predator, the pine marten, into areas where it has disappeared. Although more predation doesn’t sound good on the surface, pine martens favor eating gray squirrels over Eurasian red squirrels. It may be easier for pine martens to hunt the gray squirrels because they are less camouflaged than the red squirrels. In addition, Eurasian red squirrels evolved alongside the pine martens, so they have anti-pine marten defenses that the gray squirrels simply don’t have.
Hopefully the Eurasian red squirrel continues to increase in numbers and thrive across Eurasia. I’m personally a huge fan of the ear tufts and would hate to see that fur style disappear from the wild.
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