A group of crows is called a “murder.” Historically, there are a number of explanations for this term. One of them comes from an old tale about a flock of crows gathering together to decide the fate of another crow.

Another explanation comes from the crows viewed as a precursor of death. It's a well-known fact crows are scavengers and like to gather around dead bodies, moreover, they usually visit the battlefields and cemeteries, where the humans are only expected to be dead. Somehow they feel it and arrive to such places earlier, which made them a widespread sign of death.

But the term “murder of crows” mostly reflects a time when groupings of many animals had colorful and poetic names. Other fun examples of “group” names include: an ostentation of peacocks, a parliament of owls, a knot of frogs, and a skulk of foxes.