Many of the areas on the Eastern Plains of Colorado let you see a looong way.
That was not with a thermal. It was early afternoon.
Another time, I was calling and saw a pair coming in my direction through my bino's. I could not see them with the naked eye, even on snow, they were so far away. They did come in and a fellow PM member I took with killed one of them, his first coyote.
A coyotes ability to triangulate the location of the calling is amazing to me, even with a short calling sequence.