At 2:20am this morning I was awakened by a long coyote howl from our back yard. A few seconds later I heard the acknowledging howl from far off. Coyote packs send out scouts to find food and relay the information over long distances. If food is found - like an injured deer or meat in the garbage can - the finder calls the pack in.
These are smart animals sharpened by survival of the fittest and by adapting to nature and civilization. Unlucky cats and small dogs who are out all night are especially vulnerable. Be safe with your pets.