To Threaten a Mockingbird

No need to kill a mockingbird, just threaten one and it'll ID you and remember you for a long time to come. Those little bird brains can do a lot more than most people think.

From Proceedings of the National Academy of Sciences...

We show that Northern Mockingbirds nesting on the campus of a large university rapidly learn to assess the level of threat posed by different humans, and to respond accordingly. In a controlled experiment, we found that as the same human approached and threatened a nest on 4 successive days, mockingbirds flushed from their nest at increasingly greater distances from that human. A different human approaching and threatening the nest identically on the fifth day elicited the same response as the first human on the first day.

These results demonstrate a remarkable ability of a mockingbird to distinguish one human from thousands of others. Also, mockingbirds learned to identify individual humans extraordinarily quickly: after only two 30 second exposures of the human at the nest.