yeah it is a murder of crows. I like that one and "a mob of kangaroos"
also
Pride of lions, leap of leapards, sloth of bears, knot of toads, bouquet of pheasants, troop of kangaroos, mustering of storks, gang of elk, clouter of cats, kindle of kittens, pack of dogs, leash of greyhounds, trip of goats, root of wolves, adrift of hogs, parliment of owls, tidings of magpies, siege of herons, peep of chickens, exaltation of larks, murder of crows, unkindness of ravens, ostentation of peacocks, skulk of foxes, shrewdness of apes, crash of rhinocereses!