After 'Frankenstein' rabbits, 'zombie squirrels' are haunting Americans

Squirrels with grotesque, wart-like tumors have been spotted across the United States and Canada, particularly in states like Maine. The condition, marked by pus-filled tumors and hairless patches, has alarmed residents and fueled viral discussions on Reddit, X, and other platforms.According to reports, sightings of these afflicted animals have surfaced since mid-2023, with numbers rising this summer. Some residents have dubbed them “zombie squirrels” due to their disturbing appearance. One Reddit user recalled seeing a gray squirrel with a tumor on its mouth on July 31, initially thinking it was eating something in a flowerbed before realizing the growth was attached to its face.

The cause: Squirrel Fibromatosis

Wildlife experts identify the phenomenon as squirrel fibromatosis—a naturally occurring viral skin disease that looks frightening but poses no risk to humans, pets, or birds.

The condition is caused by the leporipoxvirus and spreads through direct contact, often when healthy squirrels encounter the saliva or lesions of infected ones. The transmission mechanism is similar to how herpes spreads in humans.Unlike squirrelpox—common in the UK and often fatal to red squirrels—this virus usually resolves within four to eight weeks. However, in rare cases, internal organ involvement can be fatal.

Wildlife biologist Shevenell Webb of Maine’s Department of Inland Fisheries and Wildlife told the Bangor Daily News that the clustering of squirrels—often around bird feeders—may be driving the spread. “It’s like when you get a large concentration of people. If someone is sick and it spreads easily, others are going to catch it,” she said.Uneaten seeds contaminated with saliva or fluid from an infected squirrel can pass the virus on to others.

Webb urged residents not to interfere. “It is naturally occurring and will run its course in time,” she noted.

Rabbits with antler-like growths

At the same time, unusual wildlife sightings have been reported in Colorado, where cottontail rabbits infected with Shope papilloma virus—also called cottontail papilloma virus—develop black, antler-like growths protruding from their heads.The disease is spread by parasites like ticks and fleas, which pass on the ailment through their bites, according to Pet MD.

While the recent sightings occurred in Colorado, the disease most frequently appears in the Midwest.“Typically rabbits become infected in the warmer months of summer when transmitted by being bitten by insects like fleas and ticks,” said Colorado Parks and Wildlife spokesperson Kara Van Hoose, per the Coloradoan.Fortunately, Colorado Parks and Wildlife notes that while the virus can spread between rabbits, it is not known to infect humans or pets and is not considered a public health threat.