I've seen this a few times. I don't think it's a chupacabra, I'm not certian about a zombie. As far as we know the zombie virus doesn't mutate the eyes. It might be a severly malnurished Riddic from pitch black :) Seriously, could've been a zed.when it looked up it had a blank expression on its face. Any thing else would've been suprised or enraged that their feeding was interupted.
Yeah, like I said, I don't know what it is, well Good ol' Grathius didn't say that he didn't know, but now I'm saying it. (Although it's pretty obvious I don't know because I said might be Chupacabra or a guy in a suit or whatever.)