A group of corvids is called a “murder”. It’s used to scare people. For example when somebody has managed to get away with something that was supposed to be impossible (sort of like in the Lion King!), you might say “it took a whole murder of ravens to do it.”
The word ‘raven’ also means, figuratively speaking, one who tells bad news; or one who would betray another person’s confidence.
That bad news-bringing meaning relates back to an old Anglo-Saxon superstition that if a bird other than the cuckoo crossed your path from left-to-right, the animal itself symbolized good fortune for travelers. A right-to left passage, however, meant trouble.