Residents of Fort Collins, Colorado, have reported sightings of wild 'demon' rabbits with black, horn- or tentacle-like growths protruding from their heads and faces, prompting a surge of online discussion and media coverage. The unusual appearance, which began circulating widely on social media in early August 2025, quickly led to speculation about the cause.
Colorado Parks and Wildlife (CPW) has confirmed that the growths are caused by a rabbit-specific virus and are not harmful to humans or pets. Officials advise the public to avoid touching the animals and to report any sightings to local wildlife authorities.
The Viral Sightings and Public Reaction
The images and videos, showing rabbits with multiple dark, spike-like protrusions, went viral after being shared by residents on community forums and social media platforms. Some viewers described the animals as resembling 'real-life jackalopes', a mythical creature from American folklore.
Others expressed concern that the animals might be suffering from a new or dangerous disease. CPW officials responded with a statement identifying the cause as Shope papillomavirus, a well-documented condition in wild rabbits.
What Is Shope Papillomavirus?
According to the College of Veterinary Medicine of the University of Missouri, Shope papillomavirus, also known as cottontail rabbit papillomavirus (CRPV), is a DNA virus that causes wart-like growths on infected rabbits.
First identified in the 1930s, it has been extensively studied and is used as a model in cancer and papillomavirus research. The virus primarily affects the skin, particularly around the head and face, where tumours develop and harden into keratinised structures.
🚨 BIZARRE OUTBREAK IN COLORADO 🚨
— Janice Nodine (@janice_nodine) August 12, 2025
Rabbits in Fort Collins are turning up with black, tentacle-like growths sprouting from their heads.
Experts say it's caused by Shope Papillomavirus — a condition the animals carry for life. Officials insist it's "not dangerous to humans" ...... pic.twitter.com/cOUmC6lQlj
While these growths can sometimes interfere with eating and vision, they are not transmissible to humans or other animals.
How the Growths Form and Why They Appear Tentacle-Like
The papillomavirus infects epithelial cells, triggering abnormal cell growth. Over time, the tumours become hard, black projections that can resemble horns, spikes, or tentacles. They often form around the mouth, nose, and eyes, sometimes in clusters, creating the striking appearance seen in recent Colorado sightings.
In severe cases, the growths can hinder a rabbit's ability to feed or escape predators, making the disease potentially life-threatening to the animal despite not being contagious to other species.
The Jackalope Connection
Folklore experts have long suggested that sightings of CRPV-infected rabbits may have inspired the American legend of the jackalope, a fictional hybrid creature described as part rabbit, part antelope. The jackalope myth gained popularity in the western United States in the 20th century, becoming a fixture in roadside attractions and novelty merchandise. The recent Colorado cases have reignited public interest in the connection between the virus and the enduring legend.
Wildlife Authorities' Advice to the Public
CPW has issued clear guidance to residents who encounter infected rabbits. People are urged not to approach or handle wild rabbits, both to protect themselves and to prevent further stress to the animals.
Pet owners are advised to keep dogs and cats away from wildlife. Any sightings of rabbits with unusual growths should be reported to wildlife officials, who are monitoring the spread and severity of the condition.
Ongoing Monitoring and Broader Context
While the recent cases have been concentrated in the Fort Collins area, there have been documented cases with similar infections in other parts of North America. The virus is primarily spread through biting insects such as mosquitoes and ticks, meaning outbreaks may be more common during warmer months.
CPW and other agencies continue to study the disease's prevalence, track new cases, and share updates with the public as needed.
