Observations by baburali

Scientific & Common Name:
This particular species of squirrel is commonly known as the “Eastern Grey Squirrel” and has the scientific name; Sciurus carolinensis (IUNC, 2016).
Habitat and Geographic Range:
The eastern grey squirrel is native to North America, in the United States it is prevalent in areas west of the Mississippi River, in Canada it inhabits the southern; more temperate provinces (Koprowski, 1994). The eastern grey squirrel is also exists as an invasive species; in Ireland, Scotland, England and northern Italy (Gurnell, Wauters, Lurz, & Tosi, 2004). Naturally, the eastern grey squirrel inhabits areas that consist of dense and continuous forests, in particular woodlands that are able to provide these squirrels with produce that can be cached and subsequently consumed; through the winter (Oak and Hickory). Additionally, these critters are commonly found in parkland areas, situated in suburban and even urban landscapes (Lawnizak, 2002). Eastern grey squirrels reside in two kinds of structures; in the winter they live in dens—holes constructed in large trees, these structures are often used as brood chambers by females. The second structure squirrels may dwell in are; nests—densely packed collection of sticks and leaves, often situated atop high-rise trees. The eastern grey is a very adaptable species and as a result; it is able to survive and prosper in an extensive number of habitats (The Pennsylvania State University, 2002).
Size/Weight and Lifespan:
According to Koprowski (1994) the eastern grey squirrel ranges from 380 to 525 mm in total length, with their tails measuring about 150 to 250 mm in length. Depending on their respective size; these squirrels have a mass of about 300 to 710 g. On the high end, these squirrels have a life span of about 12 and half years in the wild, this life span, depends on the abundance of food, the prevalence of disease/parasite and the severity of the climate (Lawnsizak, 2002) . In captivity, where the aforementioned variables are desirably controlled, the eastern grey squirrel experiences great longevity, living for about 23 and a half years (Lawnsizak, 2002).
Diet:
The eastern grey squirrel can be described as an omnivorous opportunist, which is what allows it to thrive in a plethora of environments and thus enables it to exist as an invasive species (Thompson & Thompson, 1980). As the seasons change and the type of food that is available changes, so does the eastern grey squirrel’s diet, consequently, it is able to thrive on whatever fauna and flora its habitat has to offer (Bosak, Moore, Masino & Klein, 2013). In the spring time; the squirrel will feed primarily on the buds of trees and tree flowers, in the summer it will feed on wild fruit, mushrooms, seeds and nuts. When the aforementioned sources of food are not abundantly available, these squirrels resort to feeding on insects, smaller rodents, smaller birds, bird eggs and frogs (The Pennsylvania State University, 2002). In the fall time; the eastern grey squirrel eats hard nuts like, acorns, walnuts and beech nuts, the organism will also begin to cache these nuts for the winter—in which the abundance and availability of food becomes scarce (Bosak et al., 2013).

Communication and Reproduction:
The eastern grey squirrel uses vocalizations and postures to communicate with one another, these tactics are especially intensified and utilized in the mating seasons, when communication is of paramount importance (Lawniczak, 2002). Furthermore, the squirrels use their strong sense of smell to detect physiological changes in other squirrels, males often use this tactic to find estrous and receptive females (Koprowski, 1992). Koprowski’s (1994) study found that the eastern grey squirrel practices polygynandry—where multiple males have relationships with multiple females, as many as 34 males can be be attracted to a single estrous female. According to Koprowski (1992) males choose between two strategies when attempting to find a mate: satellite or active pursuit. Satellite males disperse themselves around estrous females. Active pursuit males defend close proximity to estrous females, though both strategies have their benefits, the latter of the two tactics is generally more successful (Koprowski, 1992). Moreover, males reach sexual maturity at around 11 months of age and females reach sexual maturity at around 5 and half months to 1 year of age. Breeding season occurs twice a year, from December to February and also from May to June. Therefore, females may bear young two times in a given year, with each litter consisting of 2 to 4 juveniles (Barkalow & Soots, 1975).
Predation:
Due to its relatively small size, the eastern grey squirrel is a desirable prey for a multitude of larger species. These species include but are not limited to; grey wolves, red foxes, coyotes, skunks, weasels, bobcats and owls (Lima & Valone, 1986). When the eastern grey squirrels sense predators in close proximity, they often use vocalizations to warn other squirrels in the area of the imminent threat (Lima & Valone, 1986). In addition to the aforementioned cooperative behaviour, eastern grey squirrels are able to use their great burrowing ability, agility in trees and shear speed to evade their larger and slower predators (Lima & Valone, 1986).
Conservation Status:
Taking into account that the eastern grey squirrel is relatively populous in North America and exists as an invasive species elsewhere, it is currently regarded as “Least concern” according to “The IUCN Red List of Threatened Species”—meaning that the species of interest is not threatened and populations are stable (IUNC, 2016).
Did you know?
Since the eastern grey squirrel’s primary predators owls and hawks, the species actually has its eyes angled slightly upward, this is thought to have evolved to help the organism watch out for any avian predators in close proximity (The Pennsylvania State University, 2002).

References

Barkalow, F.S. & Soots, R.F. (1975). Life span and reproductive longevity of the gray squirrel, Sciurus c. carolinesis Gmelin. Journal of Mammalogy. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/1141781?dopt
Bosak, L., Moore, A., Masino, C., & Klein, A. (2013). Foraging and feeding behavior of the Eastern Squirrel (Sciurus Carolinensis). Journal of Applied Ecology. Retrieved from http://www.life.umd.edu/classroom/bsci338m/MdMammalogy/Bosak_et_al_2013.pdf
Gurnell, J., Wauters, L.A., Lurz, P.W., & Tosi, G. (2004). Alien species and interspecific competition: effects of introduced eastern grey squirrels on red squirrel population dynamics. Journal of Animal Ecology. Retrieved from http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2656.2004.00791.x/full
IUNC, (2016). The IUNC Red List of Threatened Species. International Union for Conservation of Nature and Natural Resources. Retrieved from http://www.iucnredlist.org/details/42462/0
Koprowski, J.L. (1992). Alternative reproductive tactics in male eastern grey squirrels: “making the best of a bad job”. Behavioral Ecology. Retrieved from http://beheco.oxfordjournals.org/content/4/2/165.short
Koprowski, J.L. (1994). Sciurus caronlinesis. Mammalian Species 480: 1-9. The American Society of Mammalogists. Retrieved from http://www.science.smith.edu/msi/pdf/i0076-3519-480-01-0001.pdf
Lawniczak, M.K. (2002). Sciurus carolinensis. Animal Diversity Web. Retrieved from http://animaldiversity.org/accounts/Sciurus_carolinensis/#c901aaf88eddc5c36c8c6803a2b0cfad
Lima, S.L., & Valone, T.J. (1986). Influencie of predation risk on diet section: a simple example in the grey squirrel. Animal Behavior. 34 (2). Retrieved from http://www.sciencedirect.com/science/article/pii/S0003347286801221
The Pennsylvania State University, (2002). Eastern Gray Squirrel. Virtual Nature Trail at Penn State New Kingston. Retrieved from http://www.psu.edu/dept/nkbiology/naturetrail/speciespages/graysquirrel.htm
Thompson, D.C., & Thompson P.S., (1980). Food habits and caching behavior of urban grey squirrels. Canadian Journal of Zoology. 58. Retrieved from http://www.nrcresearchpress.com/doi/pdf/10.1139/z80-101