Some of the most highly studied squirrels in North America are American red squirrels, eastern gray squirrels, fox squirrels, and southern flying squirrels. Read on for species-specific information about their appearance, habitats, and life spans.
American Red Squirrel
As the name suggests, American red squirrels have orange-red fur, although it can be brown at certain times of the year.1 They live in forests in the eastern part of North America.1 Compared to other types of squirrels, red squirrels are physically smaller and have longer tails.
American red squirrels can live for up to 9 years.2 For juveniles less than 1 year of age, females tend to survive longer than males.3 The opposite is true for adult red squirrels. Unlike other species of squirrel, adult male American red squirrels may actually live slightly longer than adult females, although there isn’t a huge difference between the life spans of the two genders.3
Another predictor of longevity for red squirrels is whether or not they’re born at a time in which seeds are abundant. Unsurprisingly, those born in a “year of plenty” seem to live longer.3
Eastern Gray Squirrel
Eastern gray squirrels are the type of squirrel that the majority of people are familiar with. Unlike most animals, they thrive in human-built environments and are commonly found in suburban and urban areas. They are gray, black, or even reddish in color and have long, bushy tails. Even though they’re native to eastern North America, they can be found almost anywhere on the continent and have also spread to some countries in Europe.1
Of all the squirrel species, eastern gray squirrels have the ability to live the longest. The highest recorded age for an eastern gray squirrel is 24 years.4 In the wild, they can live for up to 12 years,1 but most die before they reach 6 years of age.5
Interestingly, one of the factors that affects how well eastern gray squirrels flourish in their environment is the presence of humans.6 Roads, housing developments, and other man-made structures result in fragmented habitats that are unsuitable for the majority of wild animals. However, eastern gray squirrels adapt well to built-up environments. In the absence of most of their predators and with an abundance of discarded food to eat, they may live longer in the suburbs than in their natural forest habitat.
Fox Squirrel
The coloration of fox squirrels can vary from light gray to black, and they typically have orange bellies.7 They look similar to eastern gray squirrels but can be distinguished by their larger size and overall reddish appearance. Similar to gray squirrels, fox squirrels are indigenous to the eastern part of North America and have spread to almost every state in the US. They can survive both in forest and urban environments.
Fox squirrels can live for about 13 years both in captivity and under natural conditions.8 One of the primary factors in how long a fox squirrel will survive is the availability of food, especially for younger squirrels.7
As with eastern gray squirrels, female fox squirrels seem to live longer than their male counterparts. The oldest recorded age for a female fox squirrel is just under 13 years, whereas that of a male fox squirrel is a little over 8 years.8
Southern Flying Squirrel
Southern flying squirrels have gray backs and white bellies. They’re small and light, and like all flying squirrels, they move through the air by gliding, not flying. Despite the name, these squirrels can be found as far north as Canada, and their range extends down into Central America.1
The maximum age most southern flying squirrels can attain in the wild is about 10 years old.1 However, captive animals have been known to live for up to 17 years.9
References
1 Jackson, T. (2006). The illustrated encyclopedia of animals of America. London: Lorenz Books.
2 Lane, J., Boutin, S., Gunn, M., & Coltman, D. (2008). Sexually selected behaviour: red squirrel males search for reproductive success. Journal of Animal Ecology, 78(2): 296-304. Retrieved from http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2656.2008.01502.x/full
3 Halvorson, C. & Engeman, R. (1983). Survival analysis for a red squirrel population. Journal of Mammalogy, 64(2): 332-336.
4 Gorbunova, V., Bozzella, M., and Seluanov, A. (2008). Rodents for comparative aging studies: from mice to beavers. American Aging Association, 30: 111-119. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2527635/
5 Reid, F. (2006). A field guide to mammals of North America (4th ed.). New York, NY: Houghton Mifflin Company.
6 Haupt, L. (2013). The urban bestiary: encountering the everyday wild. New York, NY: Little, Brown and Company.
7 Koprowski, J. (1994). Sciurus niger. Mammalian Species, 479: 1-9. Retrieved from http://www.science.smith.edu/msi/pdf/i0076-3519-479-01-0001.pdf
8 Koprowski, J., Roseberry, J., & Klimstra, W. (1988). Longevity records for the fox squirrel. Journal of Mammalogy, 69(2): 383-384.
9 Austad, S. (2005). Diverse aging rates in metazoans: targets for functional genomics. Mechanisms of Ageing and Development, 126(1): 43-49.