Groundhogs and opossums are both common backyard visitors across eastern North America, but they’re very different animals. Groundhogs are stocky, burrowing rodents that eat your garden in broad daylight. Opossums are lean, climbing marsupials that scavenge at night. Telling them apart is straightforward once you know what to look for, and the differences matter if you’re trying to figure out which one is causing trouble on your property.
How They Look Side by Side
Groundhogs (also called woodchucks) are compact, heavy-bodied rodents that typically weigh 5 to 14 pounds. They have short, powerful legs built for digging, small rounded ears, and a short, bushy tail. Their fur is brown to grayish-brown, and their overall shape is low to the ground and barrel-like.
Opossums are lighter and rangier, usually weighing 4 to 14 pounds but appearing longer and thinner. Their most distinctive features are hard to miss: a pointed pink nose, dark eyes set in a white face, large hairless ears, and a long, rat-like tail with no fur. That tail is prehensile, meaning it can wrap around branches for grip. Their back feet also have an opposable toe, similar to a thumb, that helps them grasp twigs and climb. No other North American mammal has that combination.
If you’re looking at tracks, both animals leave distinct prints. Opossums have a splayed, star-shaped rear track because of that opposable toe, which sticks out at a wide angle from the other toes. Groundhog tracks are more compact and symmetrical, with four toes on the front feet and five on the back, and you’ll often see claw marks from their digging.
When and Where You’ll See Them
This is one of the easiest ways to tell which animal is visiting your yard. Groundhogs are active during the day, especially in the early morning and late afternoon. If you see a chunky brown animal grazing in your garden at 10 a.m., it’s almost certainly a groundhog.
Opossums are nocturnal. Their eyes are well adapted to darkness, and they do most of their foraging after sunset. During the day, they den up in hollow trees, brush piles, crawl spaces, or under sheds. They rarely spend more than a few nights in the same spot, wandering widely through spring and summer. In fall and winter, they settle into more permanent nests lined with leaves, but they never truly hibernate. They stay active all winter, and in cold months they sometimes shift to daytime foraging because the warmer temperatures make it easier to find food, even though their poor daytime eyesight puts them at a disadvantage.
Groundhogs, by contrast, are one of the few true hibernators in North America. They disappear underground from roughly October through March. During hibernation, their body temperature plummets from 99°F to 40°F, and their heart rate drops from 100 beats per minute to just 4. If you’re seeing an animal in your yard in January, it’s not a groundhog.
What They Eat
Groundhogs are primarily herbivores. They graze on grasses, clover, alfalfa, and dandelion greens, and they have a particular appetite for garden vegetables. Beans, peas, carrot tops, cabbage, broccoli, and tomatoes are all favorites. They eat methodically, mowing down plants close to the ground and returning to the same patch day after day.
Opossums are opportunistic omnivores, eating just about anything they can find. Their diet shifts with the seasons and includes insects, slugs, small rodents, birds, fruit, nuts, berries, grains, and carrion. They’re scavengers by nature, readily eating roadkill, pet food left outside, and garbage. In winter, when insects and small prey are scarce, they lean more heavily on plant material, remaining fruit, and nuts. They devote roughly twice as much time to feeding in fall and winter compared to warmer months. Unlike many animals, opossums don’t cache food or store extra body fat, so they need to find meals year-round regardless of conditions.
Damage They Cause to Property
The type of damage on your property is a reliable clue to which animal is responsible. Groundhog damage is distinctive and often significant. They dig extensive burrow systems with multiple entrances, and the mounds of excavated soil are easy to spot. These burrows can undermine foundations, patios, and sheds. The tunnels also dry out the roots of nearby trees. Above ground, groundhogs devastate vegetable gardens, and they claw the trunks of newly planted fruit trees, sometimes killing young apple trees by burrowing right at the base.
Opossum damage is generally more subtle. They don’t dig burrows or destroy gardens in the same systematic way. Instead, they knock over trash cans, raid pet food bowls, scatter compost, and occasionally get into attics or crawl spaces. Because they move around so much and rarely stay in one place for long, the mess they leave tends to be scattered rather than concentrated. If your vegetable garden is being stripped row by row, suspect a groundhog. If your trash is getting tipped over at night, an opossum is more likely.
Disease Risk
Many people worry about rabies when they encounter either animal, but the risk profile is quite different. Opossums are remarkably resistant to rabies. Their lower body temperature is thought to make it difficult for the virus to survive and replicate. The hissing, drooling, and swaying that opossums display when threatened looks alarming but is actually a normal bluff routine designed to scare predators, not a sign of disease.
Groundhogs are a greater concern. They are considered a rabies vector species in some states, including Virginia, though not in all jurisdictions. A groundhog acting disoriented, aggressive, or unusually tame during the day warrants more caution than the same behavior from an opossum.
Ecological Benefits
Both animals play useful roles despite their reputation as nuisances. Groundhog burrows provide escape cover, shelter, and overwintering sites for many other species, including rabbits, foxes, and various reptiles. Their digging also aerates and turns over soil, mixing nutrients through different layers.
Opossums are often praised as tick-eating machines, with popular claims that a single opossum devours thousands of ticks per season. This claim originated from a lab study that placed ticks on captive opossums and estimated how many were groomed off. However, follow-up research has consistently failed to find ticks in the stomachs or digestive tracts of wild opossums. The tick-eating reputation appears to be more myth than reality. Opossums do, however, eat plenty of genuine pests: slugs, mice, insects, and carrion that might otherwise attract other scavengers or spread disease.
How to Keep Them Out of Your Yard
Because these animals behave so differently, the deterrence strategies differ too.
For groundhogs, fencing is the most reliable approach. A perimeter garden fence should be made of welded wire or chicken wire with mesh no larger than 3 by 3 inches, reaching 3 to 4 feet above ground. Leave the top unsecured so it wobbles when a groundhog tries to climb, or bend the top 10 to 15 inches outward at a 45-degree angle. To prevent digging underneath, bury an L-shaped footer at the base or run a single strand of electric wire 4 inches off the ground and 6 inches in front of the fence. Even a simple single electric strand at 4 inches is often enough on its own.
If you need to close an active burrow, the best window is mid-July through late September. First, loosely plug all entrances with grass clippings or newspaper. If the material stays undisturbed for three to five days in clear weather, the burrow is empty and you can seal it with a 3-by-3-foot panel of heavy welded wire buried at least a foot deep. If the burrow is occupied, you can encourage the groundhog to leave by clearing vegetation around entrances, placing strong-smelling deterrents like used cat litter or capsaicin-based repellent just inside, and loosely sealing the entrance to trap the smell inside.
For opossums, the approach is simpler because they’re transient. Removing attractants is usually enough: bring pet food inside at night, secure garbage can lids, and clean up fallen fruit. If one has taken up residence under a deck or shed, block the entry point with heavy wire mesh after confirming the animal has left for the night. Because opossums move on every few days during warmer months, the problem often resolves itself without intervention.