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.
Lifespan. Due to predation and hunting, squirrels' lifespans can vary drastically. The pests experience high mortality rates in their first year of life but are capable of living up to 15 years in the wild. The average squirrel lifespan is between five and six years. Since the pests are prolific breeders, homeowners dealing with squirrel infestations see populations rise dramatically.