Groundhogs at HogHaven: Learn all about a colony of groundhogs that live in Delaware. Includes videos, sounds, pictures, and stories.
Groundhogs Day: Information about the animal and the traditions surrounding Groundhogs' Day.
Official Groundhog Site: Games, contests, prediction records, links, and Punxsutawney Phil's family.
Woodchuck: Basic information, conflicts, and public health concerns.
Woodchuck (Marmota monax): Lists the range of the woodchuck (groundhog), habits, what their tracks look like, foods they eat, and information about hibernation and reproduction. Funded by the Missouri Conservation Commission.
Woodchuck or Groundhog Fact Sheet: Fact sheet from Maryland Animal Bits.