A very large ground squirrel.
Check this link out Bill:
"Groundhogs are the largest members of the squirrel family. Though they are usually seen on the ground, they can climb trees and are also capable swimmers. These rodents frequent the areas where woodlands meet open spaces, like fields, roads, or streams. Here they eat grasses and plants as well as fruits and tree bark.
Groundhogs are the bane of many a gardener. They can decimate a plot while voraciously feeding during the summer and fall seasons."
http://animals.nationalgeographic.co...als/groundhog/