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.
In captivity, squirrels have been known to live as long as 20 years but in the wild it is estimated that gray squirrel will live to be a maximum of 12 years old. In that 12 years it is estimated that a healthy adult female gray squirrel could have had over 125 baby squirrels in the course of her life.