Ah, the Upper Peninsula — a wild, heavily forested land where the trees whisper secrets and the ground hides mysteries. If you think you’ve seen it all, think again. The U.P.’s forests are filled with strange sights that will leave you scratching your head. From interesting animal markings to geological oddities, here are 20 things you might stumble across that will make you go, “What the heck is that?”
Look Closely for These Clues
1. Buck Rubs & Scrapes
During late summer into fall, male deer — or bucks — rub their antlers against trees to mark territory and assert dominance. These “buck rubs” strip bark away, exposing pale wood beneath. This leaves behind a scent from glands near the antlers, signaling their presence to rivals and does. Nearby, you’ll often find scrapes — spots where bucks paw the ground and urinate to leave additional scent markers. Together, these signs are key indicators of deer activity, especially during the rut.
2. Bear Claw Marks
Black bears often leave vertical claw marks on tree trunks — a behavior believed to mark territory or uncover insects beneath the bark. These long, ragged scratches can appear several feet off the ground and vary in depth depending on the bear’s size and purpose. Fresh marks reveal pale wood, while older ones darken with weather and time. Coming across these signs in the woods is a humbling reminder that you’re sharing the forest with one of its most powerful residents.
3. Porcupine-Chewed Trees
Porcupines feed on tree bark, leaving behind rough, uneven chew marks that can girdle and eventually kill trees. They tend to favor hemlock, pine and other softwoods, especially in winter when food is scarce. Their feeding often circles the trunk or branches, creating a distinctive pattern that is easy to spot. While porcupines are a natural part of the forest ecosystem, their appetite for bark doesn’t always sit well with foresters or landowners.
4. Beaver-Cut Trees
Walking along ponds, streams, rivers and lakes in U.P. forests, you may notice pointed tree stumps or logs with clean, precise cuts at a 45-degree angle. At the stump’s base, you might also see wood shavings or chips. This is the work of beavers who fell trees to build dams or lodges in nearby water. Beavers might also girdle still- standing trees, chewing the bark and wood completely around the trunk into a precarious tapered hourglass. These busy rodents prefer softwood trees such as cottonwood, aspen, birch and willow growing near water.
5. Moose Tracks
Moose leave heart-shaped tracks that can stretch up to six inches long — unmistakable in both size and shape. While you might spot them in wetlands and forested areas across the U.P., the best place to find fresh moose tracks is Isle Royale National Park, which boasts the highest concentration of moose in Michigan. These animals are mostly solitary, making each sign of their presence — especially tracks — a rare and rewarding find for sharp-eyed wildlife watchers.
6. Wolf Tracks
Gray wolves have made a remarkable comeback in Michigan's Upper Peninsula. Their tracks are larger than those of coyotes, typically measuring 4 to 5 inches in length, with a more elongated shape. Unlike domestic dogs, wolves walk in a straight line, conserving energy, which is evident in their track patterns.
7. Circles in the Snow
During winter, you might notice round depressions in the snow, often surrounded by hoof prints. These are deer beds, where deer have rested and melted the snow with their body heat.
8. Hole-Peppered Trees
Ever wonder what causes the holes in tree trunks? Two common sources in the Upper Peninsula forests are yellow-bellied sapsuckers and pileated woodpeckers. Sapsuckers tap holes into live trees to feed on the sap and pileated woodpeckers excavate dead wood. When you see large rectangle holes, those are the work of the woodpeckers. The excavated nest entrances are more horizontal and the roosting holes tend to be vertical. Smaller chiseled holes are where the flaming-red crested birds feed on carpenter ants and other wood-boring insects.
Pileated woodpeckers prefer dead, dying or decaying conifers, quaking aspen, cottonwood and oak trees. You will know they are in the forest by the sharp rat-a-tat-tat pecking sound that carries through the trees.
9. Witch’s Broom
Witch’s broom is a natural deformity in woody plants, where a dense cluster of shoots grows from a single point, creating a tangled, broom-like mass — or sometimes something that looks more like a bird’s nest. It disrupts the normal growth hierarchy of branches, often due to hormonal imbalances triggered by pathogens or pests. In trees like birch or spruce, these growths can last for years and, while sometimes considered unsightly, they add an eerie, almost mystical character to the landscape.
10. Glacial Erratics
Scattered throughout the U.P. forests are large boulders that seem out of place, known as glacial erratics. These rocks were transported and deposited by glaciers during the last Ice Age, often originating from locations hundreds of miles away. Their presence tells the story of glacial movement and retreat, serving as natural markers of Earth's climatic history. Exploring these erratics offers a tangible connection to the region's geological past.
11. Lightning-Struck Trees
Trees struck by lightning exhibit dramatic scars where the bark has been blown off, sometimes spiraling down the trunk. The intense heat causes the sap to vaporize explosively, leading to these distinctive patterns. Surviving trees may continue to grow, but often bear permanent marks of the strike.
12. Fairy Rings
Fairy rings are circular formations of mushrooms or unusually lush grass caused by fungi growing outward underground. In popular folklore, they’re said to be the dance floors of witches or fairies — and stepping inside one could bring bad luck. Found in forests and grassy clearings, these rings start small and expand with age, often appearing after wet weather in late summer to early fall.
13. Hoarfrost
Hoarfrost forms when water vapor in the air rapidly freezes upon contact with cold surfaces, creating delicate, feathery ice crystals. In the U.P.’s forests, hoarfrost clings to trees, branches and even spiderwebs, transforming the landscape into a frozen wonderland. Unlike normal frost, hoarfrost develops in calm conditions with high humidity, typically on cold, clear nights. These ice formations are fragile and often melt quickly when the sun rises.
14. Ghost Pipes (aka Ghost Plant or Indian Pipes)
These eerie, white plants look like wilted flowers dipped in wax. Ghost pipes don’t photosynthesize — they steal nutrients from fungi in the soil, making them one of the U.P.’s most hauntingly beautiful plants.
15. Mysterious Mud Mounds
Small mounds of mud appearing seemingly out of nowhere in swampy areas might leave you puzzled. These are crayfish chimneys — burrow openings built by freshwater crayfish, which live underground and need access to water. They push up balls of mud as they dig, creating a miniature "chimney" above the hole.
16. Giant Puffball Mushrooms
Imagine stumbling upon what looks like a forgotten soccer ball in the middle of the woods — only to realize it’s a massive mushroom! Giant puffball mushrooms can grow up to a foot wide and are white and smooth when young. If you step on an older one, it releases a cloud of spores in a dramatic, smoky burst. Though some puffballs are edible when fresh, they should never be consumed unless positively identified.
17. The Devil’s Urn Fungus
The Devil’s Urn (Urnula craterium) is a sinister-looking fungus that resembles a black, cup-like growth on rotting wood. This eerie species thrives in the damp forests of the U.P., often emerging in early spring before leaves fully develop. Some believe its name comes from its resemblance to an old, scorched urn. While harmless to humans, its appearance makes it one of the spookier finds in the woods.
18. Rime Ice
Rime ice forms when supercooled water droplets freeze instantly upon contact with surfaces like cliffs, rocks or tree branches. It is often mistaken for hoarfrost but is denser and can build up into dramatic icy formations. The cliffs along Lake Superior frequently display stunning layers of rime ice during winter, making for breathtaking scenery. Unlike snow, rime ice is hard and can persist for days or weeks.
19. Caddisfly Larva Casings
Near streams and rivers, you might notice tiny tubes made of sand, pebbles or plant debris clinging to rocks. These are the protective casings built by caddisfly larvae, which use silk to glue the materials together. Each species has a unique building style, resulting in an incredible variety of casings. These larvae are vital to the ecosystem, serving as food for fish and indicating healthy water quality.
20. Galls on Oak Leaves
Oak trees frequently develop small, round, woody growths known as galls. These galls are caused by wasp larvae that inject chemicals into the leaf tissue, tricking the tree into forming a protective chamber. Inside, the larva grows until it emerges as an adult wasp. Though they look alarming, galls are mostly harmless to the tree and provide an interesting glimpse into insect-plant interactions.
Where to Spy These Forest Mysteries
In the U.P., you’re never far from where you can peer closely at the trees and forest floor to spot these natural wonders. Nearly 84 percent of the U.P. — about 8.8 million acres — is forestland. Here are some helpful guides to point you toward the best places to explore.
Brockway Mountain Audubon Wildlife Sanctuary
Harbor Island National Wildlife Refuge
Seney National Wildlife Refuge
Start Planning Your Adventure-Filled Days
Michigan’s Upper Peninsula forests are home to countless natural wonders, each with its story. As you plan your forest journey, be sure to choose a place to stay that allows you to rest and recharge after a full day of hiking, wildlife watching or exploring the region’s rugged beauty. There is a wide range of lodging options to fit your amenity preferences and budget. Whether it’s your first visit or one of many, the forest will be here — waiting to share more of its secrets.
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