Animal Profile: Squirrels

Love them or hate them – squirrels are here to stay. Along with birds, they are one of the few animals that urban dwellers encounter on a day-to-day basis.

Squirrels have adapted well to living in metropolitan areas. They feed on our discarded food, invade our bird feeders, and find cozy places to nest in our homes. This behaviour has earned them a bad reputation. Many people consider them pests. But, for some, their bushy tails, treetop acrobatics, and curious behaviour win us over.

In this post, I overview some basic facts about squirrels. I cover their lifespan, diet, memory, acrobatics, vocalizations, and deceitful behaviour.

Lifespan

In the wild, squirrels live very short lives. Many don’t make it past the first year. According to the Adirondack Ecological Centre, “the mean life expectancy for a grey squirrel at birth is 1-2 years.” If they reach adulthood, they live on average 6 years. In captivity, they can live up to 20 years of age.

What Squirrels Eat

Unlike mice and rats, squirrels are most active in the daytime hours. This is why we so often see them scurrying around looking for food. If they can find it, squirrels will eat a pound of food per week. That’s the equivalent of their body weight in food each week!

With the exception of urban squirrels, squirrels tend to remain in coniferous forests where they can eat and store nuts and seeds. Contrary to popular belief, their diet is quite varied. In addition to nuts and seeds, they will also eat barks, roots, berries, shoots, flower buds, insects, fruits, mushrooms, salamanders, small rabbits, and frogs. They will also chew the twigs of sugar maples to drink the sap inside.

In urban areas, you can see squirrels eating all sorts. I’ve seen them cache donuts in my backyard and biscuits in my neighbours’ empty flower basket.

Amazing Memory for Food Caches

Squirrels cache food to help them survive when nutrients are scarce. This is especially important in the winter months. They are “scatter hoarders,” meaning they hoard food in various locations. Chipmunks, in contrast, store their food in one big larder.

Several studies have examined how squirrels cache their food and if they are able to remember these caches. University of Illinois researcher Joel Brown conducted an experiment to see how well squirrels remembered their caches. After removing squirrels for weeks from their territories, he found that they were successful at finding their caches once released. Their excellent memory is essential for their survival.

Another study done by Mikel Delgado and Lucia Jacobs demonstrated that eastern fox squirrels use “spacial chucking” to remember where they store their food. Chucking is a memory technique that groups pieces of information together into broader categories. This makes it easier to recall information. Delgado and Jacobs’ study showed that squirrels cached different nut species by type and location. The authors suggest that spacial caching allows squirrels to find food with the nutritional quality they need.

As for forgotten nuts and seeds, they have a chance to grow into trees. This makes squirrel caching an important part of forest regeneration.

Competition for Food and Tactical Deception

There’s always the risk that cached food will be stolen. Squirrels have learned to deal with pilferers in a few different ways. For example, they will often leave the site of their cache to eat. This ensures that they do not give away its location. They also engage in “tactical deception.” When squirrels think they are being watched, they will pretend to bury their food. This confuses onlookers and allows them to carry their food to safety. For a long time, researchers thought this type of deception only existed in primates. Squirrels will also defend their territories from competition.

Treetop Acrobatics

One of my favourite things about watching squirrels is seeing them climb, leap, and hang from trees. Their strong back legs and light weight make it easy for them to leap long distances. Their long bushy tails help them control their jumps. They also have flexible ankle joints which can rotate 180 degrees. This allows for more control when climbing. Their tiny claws are perfect for gripping nooks and crevices in tree bark. These combined qualities allow them to descend trees headfirst, climb the underside of branches, and hang from tree limbs with no problem.

Squirrel Vocalizations and What They Mean

Squirrels have many different vocalizations to communicate with one another. Many of these are to warn other squirrels of predators in the area. Robert Lishak, an expert on grey squirrel vocalizations, breaks down the main warning calls as kuks, quaas, moans, and meows:

Kuk-kuk-kuk: You’ve probably heard squirrels make this fast-paced call if you’ve ever walked a woodland trail. It’s a sharp barking sound. The call warns others that there is an immediate danger in the area.

Quaa: This sound is often described as an “extended kuk.” It signifies that a predator is still in the area but is moving away. Check out this recording to hear an example of a “kukkukquaa” call.

Chirp-meow: The meow sound signifies that the threat is out of sight but may still be in the area.

Quaa-moans: Quaa-moan sounds are another type of warning call but meant to specify that the immediate threat is from an aerial predator.

Biologists Thaddeus McRae and Steven Green theorize that squirrels warn each other about aerial and terrestrial predators by using different calls. They argue, “aerial and terrestrial predators might be best countered by different escape strategies and therefore elicit different alarm calls that can alert [others] to whether the threat is aerial or terrestrial. Alternatively, since squirrels always retreated to a tree before initiating alarm calling, the relative risk to the calling squirrel might differ in response to aerial and terrestrial approaching predators, perhaps yielding different call compositions.”

Other animals will also take notice of squirrel alarms to help them identify predators. Some animals will mimic squirrel calls to their own advantage. The blue jay sometimes does this to scare off other birds from feeding sites.

With some practice, you can learn to identify different squirrel sounds. This can make you more in-tune with your surroundings. For more about this check out my post on sit-spots and learning baseline behaviours.

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