In addition to the nest, there is an excrement chamber. The hibernation or nest chamber is lined with dead leaves and dried grasses. The nest chamber may be about twenty inches to three feet below ground surface. It is about wide and high. There are typically two burrow openings or holes. One is the main entrance, the other a spy hole. Description of the length of the burrow often includes side galleries. Excluding side galleries, Schoonmaker reports the longest was , and the average length of eleven dens was . W. H. Fisher investigated nine burrows, finding the deepest point down. The longest, including side galleries, was . Numbers of burrows per individual groundhog decrease with urbanization.