What this actually means for the structure of the foot is a question that is still being researched today. It would seem that an accessory navicular is commonly related to pes planus. Frederick Kidner, in 1929, first theorized that the presence of an accessory navicular could be the cause of pes planus.
Successful as they are, Eastern Gray Squirrels live only 11-12 months on average, but some individuals have survived more than ten years in the wild. Factors affecting survival include the severity of winter, abundance of food, and parasites.
The total length of the squirrel ranges from 380 to 525 millimeters (mm). The tail length ranges from 150-250 mm. You can tell eastern grey squirrels apart from fox squirrels by their white tipped fur and white or grayish belly. Eastern grey squirrels often have a lot of red in their fur.