by howling just before you leave,you could be educating the coyotes if there on there way.if they didn't want to responed to the distress calls(for what ever reason)then you howl and now they decide to come in and check out the possible intruder.there watching you leave.this time of year it may take them awhile to come into a howl.as probtrapper said,decide up front what you want to do(how you want to call)and stick with it.