Wildlife officials confirm that the strange “horns” are caused by the Shope papilloma virus, a rabbit-specific pathogen that leads to wart-like tumors primarily on the head and face.

Wildlife enthusiasts and residents of Fort Collins, Colorado, are reporting a bizarre phenomenon: wild cottontail rabbits sprouting dark, spike-like growths from their heads, giving the appearance of tiny horns.

The unusual development, confirmed by the Colorado Parks and Wildlife (CPW), is caused by the Shope papilloma virus, a rabbit-specific pathogen that leads to papillomas—wart-like growths—on the animals’ skin and fur.

Local observers first noticed the growths emerging this spring, describing one rabbit that returned to the same backyard after winter, now sporting a larger, hardened mass protruding from its forehead.

“It looked like a little porcupine quill coming right out of its head,” said Marissa Cole, a resident who has been feeding wildlife in her neighborhood for years.

“I couldn’t believe my eyes—it was both fascinating and a little creepy.” CPW officials confirmed that these wart-like tumors are typically concentrated around the head and face and can sometimes grow pointed and elongated, giving the impression of miniature horns or spines.

The virus is specific to wild rabbits and cannot spread to humans, domestic pets, or other wildlife species, but authorities caution that pet rabbits can become infected if they come into contact with wild rabbits or insects that have bitten infected animals.

In most cases, CPW reports that infected wild rabbits can live with these growths without serious harm, and the tumors often shrink or disappear over time unless they interfere with the animal’s ability to eat.

“We don’t want people touching these rabbits,” a CPW spokesperson said. “It’s a wild virus, and while it won’t affect humans, it can be problematic for domestic rabbits if it spreads.”

Veterinarians in the region have advised rabbit owners to monitor their pets for unusual growths and seek immediate care if tumors appear.

Dr. Laura Simms, a local exotic animal vet, explained, “Most of the time, Shope papillomas are benign. They might look alarming, but they rarely threaten the animal’s life. Still, it’s important to get a professional assessment to make sure the rabbit can eat and move normally.”

The Shope papilloma virus is not a new discovery; it was first identified in the 1930s by Dr. Richard Shope, who studied tumor formation in rabbits.

However, the recent reports from Colorado mark one of the more visible outbreaks in suburban areas, capturing public attention due to the strange, horn-like appearance of the growths.

Wildlife biologists are studying why these tumors have become more noticeable this season, with some suggesting that environmental factors or changes in local rabbit populations may play a role.

“This is a classic example of nature showing its unexpected side,” said CPW biologist Jeremy Fields. “We see these growths, and they can be quite startling, but they are a natural response to a virus that has been around for decades.

It’s also a reminder of the interactions between wild and domestic animals.” Fields added that the virus does not generally spread aggressively in wild populations and most rabbits recover fully, though close observation is encouraged for any signs of illness or distress.

Residents are documenting their sightings on social media, sharing photos and stories that have quickly gone viral. “I’ve never seen anything like it in my neighborhood,” Cole said.

“Neighbors are calling it ‘the horned bunny.’ It’s definitely got everyone talking, and some people are even worried it’s something new or dangerous, but the officials have been clear: it’s just a rabbit virus.”

Despite the unusual appearance, CPW emphasizes that the virus is a part of natural wildlife ecology and usually poses minimal risk to the broader ecosystem.

They recommend leaving affected rabbits alone, not attempting to remove the growths, and ensuring domestic rabbits are kept separate from wild populations.

“We want people to enjoy and observe wildlife safely,” the CPW spokesperson said. “These horned rabbits are a curiosity, but they are not a threat if proper precautions are taken.”

As spring progresses and wildlife continues to emerge from winter habitats, the horned cottontail rabbits serve as a striking reminder of the unexpected ways that viruses can manifest in nature.

While the spiky growths are startling to casual observers, experts hope the attention will raise awareness about the importance of monitoring wildlife health and understanding the interactions between wild and domestic animals in suburban environments.

Public fascination with the “horned” rabbits is spreading, and wildlife officials encourage people to report sightings to CPW for ongoing research and monitoring.

Meanwhile, pet owners are urged to remain vigilant, and local vets are prepared to assist any domestic rabbits that might come into contact with the affected wild population, ensuring a safe and informed response to this unusual viral outbreak.