You won’t believe what’s happening to deer in the US as terrifying black warts start showing up on their skin and scientists warn about what it could mean for wildlife

If you thought the world had seen it all after the viral “Frankenstein rabbits” and those eerie “zombie squirrels,” brace yourself—because now deer are joining the bizarre wildlife spotlight. Across Pennsylvania, Wisconsin, and even Maine, people are spotting what can only be described as warty, black-bubbled deer wandering through backyards and forests. And yes, it’s just as unnerving as you might imagine.

One Reddit user shared a photo of a deer they saw a month ago right outside their home, typing almost in desperation: “Not sure what’s wrong with her or how we can help. Gunshot wound? Tumor? Fireworks? Prion disease? Don’t know what to do.” Another posted a close-up of a deer with lumps on its face and chest, asking the simple but haunting question: “What’s wrong with this deer?”

So what is going on? Wildlife experts say these strange growths are caused by something called deer fibroma, a virus-specific condition linked to a papillomavirus—similar to the virus that gives cottontail rabbits their own warty bumps. The Maine Department of Inland Fisheries and Wildlife explains that these growths appear as dark, firm lumps, often bare of fur and sometimes cracked or fissured. Most are small, just a few centimeters, but in some cases, they can cover larger areas of the deer’s hide.

Before anyone worries too much, here’s the reassuring part: deer fibroma isn’t contagious to humans or other animals — it only affects deer. Dr. Kristin Mansfield, a wildlife veterinarian in Washington, explains that the virus spreads from deer to deer through shared feeding spots, resting areas, or even the trees that bucks use to mark their territory. The good news is that a healthy deer’s immune system usually takes care of it on its own, and the warts gradually shrink and disappear over the course of a few months.

Surgical removal is possible for captive animals, but experts generally advise leaving wild deer alone. Interfering can sometimes do more harm than good, and in rare cases where the warts prevent the animal from eating or moving properly, humane euthanasia might be considered.

As for why we’re seeing more of these “mutant” animals, scientists point to climate change. Warmer temperatures allow ticks and mosquitoes to thrive, bringing diseases to areas that previously never had them. Dr. Omer Awan of the University of Maryland notes that illnesses like Lyme disease are popping up in regions that never had them before, like Maine and southern Canada, and people are noticing—and sharing—these unusual sightings more than ever thanks to social media.

The reality is a bit sobering: our changing environment is affecting wildlife in ways both obvious and hidden, but always real. Those deer covered in warts might seem straight out of a horror story, but they’re really a reminder of nature’s resilience—and that sometimes, the oddest sights are just signs that the natural world is struggling to adapt and survive.