Crows will not only remember your face and go after you repeatedly if you bother them, but they will also teach other birds to do the same. Their scolding and physical harassment can last for years, possibly for the life of the bird.
Crows are the devil-birds of the sky. Not only do they look like the kind of bird that would be perched on the shoulder of a Disney villain, they do frighteningly smart things. For one thing, they use tools to assess and find food. They even make frogs explode. (The crows swoop down and tear the frogs' livers out. The frogs swell up in a belated self-defense reflex. Unfortunately, they're used to swelling up with their livers in place to provide counter-force and so they split themselves open.) Now it's been shown that crows aren't just smart, they're organized.
Two researchers at the University of Washington trapped, banded, and released crows at a site near Seattle. They did so wearing distinctive masks - to freak out not only the crows but any poor hikers who were going by. Unlike the meek Seattle hikers, the crows started fighting back as soon as they were released. They scolded the researchers, which didn't seem too sinister until the scolding brought other nearby crows into the fray. Neighboring crows joined in, until at some release sites the researchers were being scolded and dive-bombed by fifteen crows at a time.
When the researchers put the masks back on and ventured out, they were again scolded, dive-bombed, and mobbed by crows. But not all the mobs contained crows that were banded. This meant that some of the crows that had participated in the original scolding sessions remembered the researcher's 'faces' and went on the offensive when they saw those faces again. The crows they were with joined in the mob, and the masks became known as trouble to an even larger population of crows. Researchers have only tested crow memory for five years, but they believe that the birds remember faces for their entire lives - fifteen to forty years. Get on the wrong side of one crow in your forties or fifties, and you could be mobbed everywhere for the rest of your life.