Across neighborhoods in the U.S. and parts of Canada, gray squirrels with grotesque, pus-filled tumors have been appearing in backyards, leaving residents both horrified and fascinated by the so-called “zombie squirrels.”

Across the United States, a growing number of backyard watchers have spotted gray squirrels with grotesque, pus-filled, wart-like tumors skulking around bird feeders, lawns, and gardens, leaving homeowners shocked and bewildered.

The phenomenon, first documented in mid-2023, has surged again during the summer months, with sightings reported in states such as Maine and extending into parts of Canada.

Social media platforms like Reddit and X have become hotspots for users sharing photographs of the afflicted animals, many of which show alarming hairless patches, fluid-filled growths on their faces, and hunched postures that earned them the nickname “zombie squirrels.”

“At first I thought it was eating something from my front beds, but then I realized it was on its face,” one Reddit user posted on July 31 after noticing a gray squirrel with a tumor on its mouth.

The photo, which quickly went viral, revealed the disturbing extent of the lesions, with the animal appearing lethargic and unsteady.

Another homeowner in Maine described seeing multiple squirrels gathering near a feeder, some of them covered in similar wart-like tumors. “It’s unsettling but fascinating,” she said. “They just move slowly, almost like they’re haunted.”

Wildlife experts, however, urge the public not to panic. The creatures are likely suffering from squirrel fibromatosis, a viral skin disease caused by leporipoxvirus. While the tumors look alarming, the condition is naturally occurring and poses no threat to humans, pets, or birds.

Shevenell Webb of Maine’s Department of Inland Fisheries and Wildlife explained to concerned residents that the virus spreads through direct contact between squirrels, particularly through the lesions or saliva of infected animals.

“It’s like when you get a large concentration of people. If someone is sick and it spreads easily, others will catch it,” Webb said.

The dense gatherings around bird feeders can unintentionally amplify the spread. “Like a lot of people, I love watching birds,” she added. “But when multiple squirrels crowd a feeder, exposure risk increases if one has the virus.”

The disease, often mistaken for squirrelpox more common in the UK, causes wart-like growths that can ooze fluid.

In most cases, the lesions clear up naturally within four to eight weeks, though severe infections can impact internal organs and even lead to death. “I would not recommend trying to capture a squirrel that has the virus,” Webb cautioned.

“It is naturally occurring and will run its course in time.” Despite their alarming appearance, these squirrels are not aggressive, and the key for residents is to maintain a safe distance and allow nature to take its course.

Experts note that environmental factors, including crowded feeding spots and urban wildlife interactions, may be contributing to the recent surge.

Backyard bird feeders, while offering enjoyment for people, can create unintended points of contact between squirrels, increasing transmission rates.

“The behavior of squirrels is naturally social around food sources,” Webb said. “Unfortunately, this creates perfect conditions for viral spread when one individual is infected.”

Interestingly, the rise of these so-called “zombie squirrels” coincides with other viral outbreaks among wild animals.

In Colorado this month, cottontail rabbits have been reported growing black, tentacle-like spikes on their heads due to the cottontail papilloma virus, also known as Shope papilloma virus.

Both events highlight how viral diseases can emerge among local wildlife populations, producing visually startling effects that draw public attention while remaining largely harmless to humans.

Wildlife rehabilitation centers and sanctuaries have reported increased calls from concerned residents seeking guidance on whether to intervene.

Evelyns Wildlife Refuge confirmed receiving numerous photos of infected squirrels, noting that in most cases, the animals simply need time to recover on their own.

Staff stress that handling infected squirrels can be dangerous for the animals and counterproductive for disease management.

For backyard enthusiasts, the message is clear: observe, document, but do not interfere. Maintaining a safe distance, disinfecting feeders, and limiting close contact with infected animals can help slow the spread while keeping humans and pets safe.

Experts say that while the visual impact of the tumors can be disturbing, the outbreak is a temporary and self-limiting occurrence in most cases.

“It’s a reminder of the delicate balance between humans and urban wildlife,” Webb said. “These squirrels are not monsters—they’re animals dealing with a viral infection, and nature has its own way of resolving it.”

The surge of “zombie squirrels” has captured public fascination, sparking viral posts and widespread discussion online, but for wildlife authorities, the focus remains on education, observation, and letting natural processes take their course.

While the phenomenon has become a talking point among homeowners and social media users alike, experts emphasize that panic is unnecessary. The squirrels, though unsettling in appearance, represent a natural wildlife cycle.

As long as residents respect boundaries, avoid direct contact, and allow time for recovery, these unusual visitors are likely to return to normal activity once their tumors heal.

The recent spike in cases has also sparked broader discussions among ecologists and urban wildlife managers about how human habits—feeding wildlife, urban expansion, and habitat interactions—can influence viral transmission patterns.

By understanding these dynamics, communities can better coexist with urban wildlife while minimizing unnecessary health scares.

The bizarre and eerie images of squirrels with oozing, wart-covered bodies may be unforgettable, but experts stress that these creatures are a curiosity rather than a threat, offering a rare glimpse into the complex interactions of wildlife diseases and urban environments.

Observers are advised to watch from a safe distance, document sightings responsibly, and share information with local wildlife authorities if necessary.