Hibernation takes place in a side chamber along one of the underground corridors of the burrow system. While hibernating, the woodchuck rolls itself into a ball and tucks its head between its hind legs. Hibernating chambers are thought to be located under the roots of trees. Woodchucks somehow seem to know when to wake up, controlled by a circannual clock, but actual emergence depends on the daily temperature. Soon after leaving hibernation, sexually mature woodchucks begin the reproductive process.
Males tend to venture above ground first and fight vigorously with each other.
Woodchucks are not monogamous and males do not take part in raising the offspring. There is some evidence that woodchucks associate in groups which are dominated by a single adult male, discouraging other males from mating with his females. As a result of deforestation and maintenance of the land of cultivated fields and pastures, the woodchuck has thrived and multiplied. Typical woodchuck habitat includes rolling farmland interspersed with grassy pastures, small woodlots, and brushy fencelines. Woodchucks especially prefer forest edges and openings though they are never far from cover, and they are partial to loam and sandy loam soils for burrowing.