Any body slightly interested in calling should study the vocalizations and learn what they mean and why they do em.Coyotes are territorial....or I should say a dominate pair are territorial,and will stay with the same area pretty much their whole life.When you hear coyotes howling in the evening it is a calling to the neighbor..."Hey you home?"If nobody answers...well lets go investigate!This is the exact reason a good trapper picks up dung from other areas and will use it as an attractant,at a trap set...strange coyote just chit in MY territory and buried some food!Or the guy that uses urine....same reason a dog will piss on every fire hydrant they come by...its a marking post.."Hey,I was here",so the next one that comes by piss's over him,shows his dominance....like a gang banger and graffitti!So when a dominate dog hears a strange howl(they know each others sound just like you know people your around a lots voice)they are coming to check it out.Or an adolescent dog that has been run off,and is searching for a mate.Howling works year round,and they always dont answer back,often times they (especially young un confident dogs)come in completly quiet(this is where a decoy dog is priceless,they hear and see a lot better than you and I,and will tip you off to a customer)Then there is the challenge bark which during denning/mating season will infuriate the dominate pair...again,they come in quiet,but will often charge in all riled up PISSED OFF!!! The locate howl is invaluable as well,gets them going...lets you know where they are laying up...hanging out...then you slip in and call.This tells you where you want to be calling to,and what direction they will likely come from.I used to have a siren on all of my trucks for this,just like all the neighborhood dogs...sirens entice a howl!!In areas you have ground squirrels...listen to them when you are calling!!!!!!There warning whistle has cost many a coyote his life,same thing with Magpies or crows.....listen to nature....everything is afraid of a predator and will warn their buddies