Flock, pack and herd are found in "beginner" English books all the time. Ask the nearest three year old to fetch the animal/farm/zoo book.

Those three words also stand on their own. "That herd looks unsettled" "Can you hear the pack howling?" etc.

I've yet to hear "murder" without "of crows" following it, so I reject it as the normal word.

(Native English speaker.)