That's the question sparked by a video that's gone viral. The clip shows a bird, with its beak in the air, and a human stroking its head. But looked at from a different angle, the beak appears similar to bunny ears.
Dan Quintana, a senior researcher in biological psychiatry at the University of Oslo in Norway, posted the video to Twitter Sunday, alongside the caption: "Rabbits love getting stroked on their nose."
He told CNET he "thought it was fairly clear that the video was of a bird... as you can see the translucent nictitating membrane sweep across the eye horizontally (rabbits don't have membranes like this) and the positioning of the 'ears' are a little strange."
"I made the rabbit comment to prime readers into thinking it was actually a rabbit, to give it a fighting chance at least," Quintana said. "When you only see the beak in your peripheral vision, it really seems like they're ears. Without this misleading cue, I thought most people would have seen a bird."
The optical illusion reminded some of similar debates: "The Dress," in which some people saw a black and blue dress that others saw as gold and white, and "Yanny or Laurel," in which some people heard a computerized voice saying different names.
"Here's my rabbit," one Twitter user joked, posting a video of a large snail, while another user said the video showed "Clearly a bird. The 'ears' are hard and unmoving. Also in the wrong place."
"Seriously what am I looking at? I can't handle this kind of mental pressure right now," someone tweeted.
Quintana said, "About two-thirds of people are insisting it's a bird, and the remainder is either insisting it's a rabbit or can't decide."