One of the major stumbling blocks of wolf hunting, is they prefer to hunt at night, preferring moon-lit nights which are also preferred by animals that move around eating at night - ie their food, the ungluates. It's a Disney deal that they are only howling at the moon. In moose camp, we hear then all night, every night, moon or no moon. You only hear the packs howling while they are actually chasing moose. Single wolf or coyote calls are locator calls.
: Since it's illegal to hunt at night, wolves aren't seen often, hense, aren't shot often.