Next time you see a group of crows, look closely. Try to remember which one is which, and see if you can tell the difference between them the next time you pass. Odds are good that you can't; they're crows, which makes them all big black birds. On the other hand, every last one of them very likely remembers you as the weird human who kept staring at them. We know this, because researchers in Seattle performed an experiment with some crows around their college campus. They captured seven of the birds, tagged them, then let them go. And they did it all while wearing creepy skin masks, because it was funny:
the scientists weren't just playing out horror movie fantasies -- they were testing whether the crows could recognize human faces or not. It turns out they can. To a frightening degree: Whenever the scientists walked around campus with the masks on, the crows would "scold" and dive-bomb them... because along with the ability to recognize us as individuals, the researchers also learned that crows can hold a grudge. And pretty soon, it wasn't just the first seven crows reacting. Other birds, ones that hadn't even been captured in the first place, started dive-bombing the scientists as well.
In case you think they were just telling each other "get the guy with the mask," they weren't: The test was repeated with multiple people wearing multiple masks, and without fail, the crows left the masked men who hadn't messed with them alone, but went murder-crazy on the mask that had been worn while messing with them.