A Tale of Two Squirrels

Post by Jen Berlinghof and Allison Frederick

Everywhere you look this time of year, animals are tending to nests during spring’s baby season. Squirrels are very active at this time with the bounties of spring. Food reserves from winter are low, and energy demands are high with young in the drey (their leafy, treetop summer homes) demanding to be fed. So, squirrels turn from their habits of digging for winter caches and begin eating buds, flowers, fungi and lichens. They will take advantage of almost ANY food source at this time of year!

There are six species of Sciuridae, or “creatures that sit in the shadow of their tails” found in the Lake County Forest Preserves. This family of rodents includes eastern chipmunks, thirteen-lined ground squirrels, woodchucks, and southern flying squirrels. These guys are pretty distinctive yet, the most common members of this group are often mistaken for each other: the eastern gray squirrel (Sciurus carolinensis) and the fox squirrel (Sciurus niger) Let’s unwrap the tale of these two squirrels.

While both of these squirrels are ubiquitous in the area and generally share the same nesting behaviors and nut-centric diet, they are physically different and prefer different habitats. Gray squirrels have primarily gray fur on their backs, white fur on their bellies, white-tipped tail hairs, and are generally smaller and more slender than fox squirrels. Fox squirrels are more burley than gray squirrels with a reddish outer coat and a buffy belly and the tail hairs are tipped with reddish-brown. While both species can vary in color, the most common variation we see in Lake County, Illinois is a black squirrel which is merely a color morph of the eastern gray squirrel, and more common the further north you travel.

While many of their behaviors are similar, these two species occupy different hours of the day and are not generally seen together. Gray squirrels are the early risers of the two, and are considered crepuscular, or most active at dawn and dusk. They sleep during the day and generally tuck themselves into their drey in the early evening before sunset. Fox squirrels, however, are diurnal, or active all day and sleep all night. Scientists speculate that these size and behavioral differences might be some of the reasons these two species seem to prefer different habitats.

Data from the citizen scientist program Project Squirrel has shown that more gray squirrels occupy the more wooded and populated eastern part of Lake County, Illinois. With a higher concentration of nut-bearing trees in these areas, the gray squirrel’s favorite food is abundant, which may give them the competitive advantage as more efficient foragers. The smaller, more nimble gray squirrel spends most of its time in the trees and thus prefers more densely wooded areas.

Fox squirrels, on the other hand, seem to dominate in the more open savanna habitats and rural areas of the western side of Lake County, Illinois. The fox squirrel spends more time on the ground than gray squirrel, and in more open woodlands near fields and prairies. Prey animals, like squirrels, are more susceptible to predators in these open areas with fewer places to camouflage and hide. Here, the fox squirrels may have a competitive advantage over gray squirrels, due to their larger size and greater strength. These findings are in accord with the favored natural habitats of the two species, where fox squirrels do better in the more risky open areas and forest edges, and gray squirrels prefer denser forest.

You, too, can help Project Squirrel by becoming a citizen scientist and simply observing the squirrel behavior in your own yard. And a special note for this spring season: It is common to see infant wildlife in the preserves this time of year. Taking the proper measures when dealing with infant wildlife will help the baby and protect local habitat. In most cases, infant wildlife should be left alone. Learn more about how to assess when infant wildlife needs assistance before taking action. Happy trails!

Bird-eat-bird world

Post by Jen Berlinghof

I remember the first time I saw it happen. It was a frigid Sunday in February, sixteen years ago. I had just started working for the Lake County Forest Preserves. The deep cold, the kind that temporarily freezes your eyelashes together every time you blink, kept potential hikers away from Ryerson Conservation Area that day. I ventured out only to fill the bird feeders, and the chickadees, juncos, cardinals, and woodpeckers quickly gathered around for a feast. I thought they would be my only visitors of the day. Then, a cacophony of bird wings ruptured the quiet. Bird visitors fled from the feeders in all directions. In a low hanging branch of a nearby oak, one bird remained: a Cooper’s hawk. It was devouring a mourning dove that had just been pecking around under the feeders only moments before.

Cooper's hawk eating bird Continue reading