And this evening, on Boing Boing, I've just read an anecdote in which the expression murder of crows was used. Okay, that's a sign. I need to discover the truth about this harsh noun.
The American society of Crows and Ravens says
A "murder" of crows is based on the persistent but fallacious folk tale that crows form tribunals to judge and punish the bad behavior of a member of the flock. If the verdict goes against the defendant, that bird is killed (murdered) by the flock. The basis in fact is probably that occasionally crows will kill a dying crow who doesn't belong in their territory or much more commonly feed on carcasses of dead crows. Also, both crows and ravens are associated with battlefields, medieval hospitals, execution sites and cemeteries (because they scavenged on human remains). In England, a tombstone is sometimes called a ravenstone.The Grammarphobia Blog, on the other hand, suggests the expression might be a fanciful one and not a genuinely medieval collective noun.
The Boing Boing post reported a study showing crows can recognise individual human faces.
I think they are one of the smartest birds around. And I like them.