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 fox squirrel (Sciurus niger), also known as the eastern fox squirrel or Bryant's fox squirrel, is the largest species of tree squirrel native to North America.astern Fox Squirrel pausing from building his nest in an attic in Berkeley, California. In captivity, eastern fox squirrels have been known to live 18 years, but in the wild most fox squirrels die before they become adults. Their maximum life expectancy is typically 12.6 years for females and 8.6 years for males.