Coyote howler works good in big wide open country. I've used them to roost and to locate in the morning. If I think a bird is close I may not use it, but only because it's so loud. I currently use a Primos without the tube.
Turkeys know a coyote by sight. I don't believe they are capable of hearing a howl across a field and thinking that they need to be careful because there is a coyote close by. Same as with an owl or a crow. They aren't thinking.......hey....it's too early for that crow, or it's too late for an owl. It's purely a shock gobble.