Some cottontail rabbits in Fort Collins, Colorado, have been drawing attention because they have wart-like growths on their faces that look like horns.

Viral photos have inspired a fluffle of unflattering nicknames, including "Frankenstein bunnies," "demon rabbits" and "zombie rabbits."

The growths are most likely caused by a summertime virus common in some U.S. states, but wildlife officials say there is no risk of transmission to humans or other animals.