In my area of the country squirrels are everywhere. My dog loves/hates them. Chasing them has really kept him in shape. While some people like squirrels, many consider them pests and they are listed as one of the most invasive species.
Squirrels are fascinating, adaptable little creatures who are able to survive and thrive in a wide variety of environments.
- There are a lot of species of squirrel: There are an estimated 278 species of squirrel. Squirrels are found on all continents except for Australia and Antarctica. The most common type of squirrel in the U.S. is the Grey Squirrel (there are eastern and western varieties)
- They Are Great Jumpers: Squirrels can leap a span equal to about 10x their body length! Ever wonder how a squirrel can survive a relatively high fall that would kill a dog or human? Check out this related IFOD on Can a Mouse Survive a Fall From a High Rise?
- Very Dexterous: “They can rotate their ankles 180 degrees, and so keep a grip while climbing no matter which way they’re facing.” Source.
- Young Squirrels are like Teenagers: “Tree squirrels in general experience high levels of mortality as juveniles, but survival increases once individuals reach adulthood at 1 year of age.” Source. According to squirrel experts at the Smithsonian, squirrels can learn about safe travel from watching other squirrels traverse difficult branches.
- Squirrel Tails Are Pretty Cool (pun intended): The big bushy tails of squirrels are an important device for regulating their heat. Squirrels have been found to use their tail to shade themselves from the sun and the lighter shade of fur on the underside of their tails absorbs less heat when the tail is flipped over them. Their bushy tails also are used as a blanket on cold nights. More amazingly, squirrels can regulate the blood flow to their tails for temperature regulation purposes. “By pumping more blood into the tail, the squirrel regulates its body temperature like a car radiator. If its body needs cooling, blood is pumped into the tail for 360 degree cooling. If its body needs to maintain heat, blood circulation is reduced in the tail keeping heat close to its core.” Source. Their tails are also used for communication and as a counterbalance.
- Great Vision: Most rodents are nocturnal and use their whiskers to navigate. Squirrels are diurnal and have really good eyesight. “Their peripheral vision is as good as their focal eyesight. So, they can see what’s above and beside them without moving their heads, making it hard to sneak up on them. Their color vision is not so great, but their pale-yellow lenses act as natural sunglasses by cutting down on sunlight glare.” Source.
- Rally Squirrel: During the League Division Series between the St. Louis Cardinals and the Philadelphia Phillies in 2011 one or more grey squirrels interrupted play and/or took the field over three different games. The Cardinals scored 5 runs after Rally Squirrel appeared in one game and the Cards went on to win the World Series in 2011. Throughout the playoffs “Rally Squirrel” was a thing. You could buy stuffed Rally Squirrels as well as shirts and other merchandise. Rally Squirrel even has its own baseball card!
- Squirrel Bridge: In 1963 Amos Peters, owner of a construction company, was tired of seeing squirrels being hit by cars on a street by his office in Longview, Washington so he created a bridge across the street for the squirrels. It’s known as the Nutty Narrows Bridge.
- They Can be a Menace: They eat our pumpkins off our front porches, they eat bark off some trees which can kill the trees, they can carry disease, they find their way into our attics and homes and can gnaw through electrical wiring. They are one of the top causes of power outages in the U.S.
Where Did All the Squirrels Come From?
Even though squirrels seem to be everywhere, as recently as the mid-19th century they were not common in urban and suburban areas. In the fascinating study The Urbanization of the Eastern Gray Squirrel in the United States, Etienne Benson of the University of Pennsylvania notes that squirrels used to only be found in woods and forests and were hunted for food. Urbanization of squirrels first occurred in 1847 in Pennsylvania when three squirrels were placed in a public park and provided with food and shelter. People in Philadelphia loved having squirrels in the park and visiting the squirrels was a major attraction. There is record in 1856 of a crowd of over 100 people in NYC who gathered to look at a single squirrel – so, squirrels were pretty rare.
In the second half of the 19th century the fashion of having squirrels in public parks spread throughout the east coast with some parks planting nut-bearing trees to squirrels would have food to eat. The squirrel population really took off in the 1870s with the rise of landscape park movement of Frederick Law Olmstead. Compared to the small city squares like Boston Common, landscape parks such as Central Park in NYC were perfect locations for squirrels to thrive. Great quote from the Benson paper:
For urban reformers of the time, squirrels and other animals helped enliven urban green spaces and contributed to a bucolic atmosphere that was entertaining, enlightening, and salubrious. The gray squirrel was seen as a particularly desirable park resident, since it was understood to be, as the naturalist John Burroughs would later write, “an elegant creature, so cleanly in its habits, so graceful in its carriage, so nimble and daring in its movements,” and one that “excites feelings of admiration akin to those awakened by the birds and the fairer forms of nature.” Urbanites who encountered such admirable creatures living in the middle of the metropolis would, reformers hoped, be projected into a more wholesome and natural world, if only for a moment.
Feeding squirrels at urban parks became a pastime of park-goers. With plenty of food from people as well from trees squirrel populations in landscape parks exploded. From the introduction of less than 50 squirrels in the late 1870s, more than 1,500 squirrels called Central Park home a mere six years later!
Soon, squirrels moved beyond just parks and into neighborhoods. Again from the Benson paper:
Attics and spaces within walls offered nesting sites that exceeded even the best tree holes for security against predators and the elements. Human food waste provided a year-round source of nourishment that partly made up for the paucity of nut-bearing trees in many locations. Telephone and electric power lines provided security from dogs and cats and facilitated transit across the increasingly crowded, busy, and dangerous city streets.
The offspring of squirrels that had learned to exploit a new food source, route, or nesting site often incorporated those discoveries into their own behavioral repertoires. The nuts and nest boxes offered by squirrel lovers were crucial to the establishment of squirrel populations in American cities, but the persistence and growth of those resilient populations depended on the squirrels’ adaptation to an environment that had little in common with the woodlands where they had evolved.
How many squirrels live in the 840 acre Central Park currently? Believe it or not, there is a “squirrel census” of Central Park so we actually know the answer. The census, published in June of 2019, concluded that there are 2,373 eastern grey squirrels who live in Central Park. Many thanks to the 323 volunteer “Squirrel Sighters!” For $75 you can buy a really cool looking copy of the report (might make a great gift!). You can buy it here. You can read more about the census in this NY Times article.