Few Pennsylvania animals wear their calendar as openly as the groundhog. Across 4,578 records, reports run strong from March through October, then collapse to nearly nothing from November through February, a gap that maps the deepest true hibernation of any mammal in the state.
Five months underground
A hibernating groundhog is not merely sleeping. Its body temperature falls to within a few degrees of freezing and its heart slows to a handful of beats a minute while it lives off the fat built over summer, a state it holds from late fall until early spring. The February records that do appear belong partly to the first stirrings of the breeding season, when males emerge early to search burrow systems for mates, the same midwinter moment behind the state’s famous Groundhog Day tradition.
A grazer of open edges
Groundhogs feed in the open and live underground, so they concentrate where pasture, field edges, roadsides, and park lawns meet diggable soil. Philadelphia, Allegheny, and Montgomery counties lead the record, and the open ground at Valley Forge National Historical Park, Marsh Creek State Park, and French Creek State Park shows the pattern: grazing animals never far from a burrow mouth with several exits.
Status in Pennsylvania
NatureServe ranks the groundhog S5, Secure, in Pennsylvania. The species is native to the state, and USGS NAS does not list it as nonindigenous here.
