Groundhog Observations 2003-2017
By Susan & Joseph Sam
WE believe groundhog behavior has been misinterpreted and misunderstood due to lack of observation time of groundhog families and lack of equipment to maximize observations. With the addition of trail cameras in 2016, we are proving what we have believed to be true from past year’s observations.
IT has been thought that the father does not assist in caring for the young because he is not needed. It’s been thought he was not even tolerated and never allowed to enter the nursery. We disagree, in part. The nest chamber has been documented by W.J. Schoonmaker to be about sixteen inches wide and fourteen inches high  While this nest accommodates an adult male and female, it would unlikely be large enough to accommodate two adults as well as babies. While the male may not actually enter the burrow in the weeks following the birth of babies, he has been documented at each opening of that burrow. He has also been documented leaving his scent by marking objects in the barn near, and surrounding, the natal burrow.
WE’VE been saying for years that the male groundhog does not sever ties to his mate when babies are born. We have shown the presence of the male in both video and photographs after the birth of babies. With the addition of trail cameras, we are able to actually confirm his presence inside the barn where the natal burrow is located. We have also documented 6 different males interacting with juveniles; George, Luke, Raggedy, Fred, Reggie, and in 2021, Milo.
IT’S been thought the female drives the male from the den when she is near to giving birth or has given birth. We have found that once the female has given birth, the role of the male changes. In addition to visits to his mate, he makes rounds to other burrows which will be used for training of the babies after they emerge from the natal burrow. He also assists in burrow maintenance. In 2021, male Milo took over the care and raising of the 4 young born to female Ash after she left in mid June.
IT’S been thought that groundhogs have a winter den and a summer den. On our property, they have multiple summer dens. The “winter” den is used for hibernating, mating, and birth of the young. It is a home base and used continually. The “summer” burrows are used in training and raising of the young as well as for an escape from predators.
WE’VE observed the same female and male mated in more than one year (Wilhelmina & Gregory, Wilhelmina & Woodrow). It’s very possible that some groundhogs mate for life, assuming the survival of each. Researchers have stated the female may have more than one mate in a year  and we agree this may have occurred in our population. For example, in 2015 confirmed male, Raggedy, may have been a second mate to our female, Heidi. Raggedy was her mate in 2016 and most likely again in 2017.
WE believe there are a number of groundhog actions that have been misinterpreted and misunderstood. Mounting behavior is one example. While this is seen in mating, we’ve also seen it in play between juveniles and also between adults and juveniles. We call this “overlapping behavior,” actions that are used in multiple circumstances.
CHASING is another example. We have seen various chases, some with mother chasing young, mate chases, and chases between other groundhogs. Chases are not necessarily a hostile, aggressive act. They may be disciplinary, playful, or perhaps for training or exercise. Occasionally we have observed a groundhog briefly chase a rabbit or bird.
VARYING environments may necessitate adaptations in groundhog behavior, and individual behavior may differ somewhat. We don’t believe, however, that the activities and behavior we have observed and documented is exclusive to our property. In fact one researcher, Paul Meier, studying woodchucks in Ohio found that adult males associated with females throughout the year and often from year to year. 
OUR observations have convinced us that groundhogs operate as a family unit. Loss of the mother while she is still nursing leaves the young without nutrition. Loss of a male in the family leaves the family more vulnerable to predators and animals that would take over their burrows. While the female may do the majority of training, increasing observations indicate a role here as well for the male.  Most or all juveniles disperse in late July or early August. They have a lot to learn in a short time! Much like a baby boot camp.
 W.J. Schoonmaker, The World of the Woodchuck, page 105
 Christine R. Maher, Melissa Duron, Journal of Mammalogy, Vol. 91, Issue 3, 16 June 2010, Pages 628-635
 Meier, P.T. Social organization of woodchucks (Marmota monax). Behav Ecol Sociobiol 31, 393-400 (1992).
 See YouTube videos: Groundhogs 2017, Groundhogs, Male-Juvenile (Baby) Interactions, and George and Chucklings 2010 https://www.youtube.com/user/chuckland2009