Rich Higgins pointed something out to me a while back that I had never really considered before. Desert coyotes never get REALLY hungry. There's always something for them to eat whether it's animal, plant, or insect matter. They may LIKE some things better than others but unlike coyotes that live in harsher climates, there's never any reason for them to go hungry. That said, I've come to the conclusion that desert coyotes are kind of lazy. You really have to catch one in the right state of mind for one to come a mile to your call. If they are up and moving, the farther they come I think. If they are laid up relaxing, I think you can give them the sweetest serenade of bunny blues they've ever heard and they won't budge sometimes if they determine that the distance is too great. What I'm getting at is this. If you're in an area that has a good population and you see another spot that you think would be a good place to call even though it's only a few hundred yards from that last spot, try it anyway. You just may have closed the distance enough that a lazy, sleepy coyote will come see what's up. Another reason I'm leaning toward this line of thinking is that the vast majority of coyotes I call in show up within 2 minutes or so, sometimes as little as 30 seconds. I don't sit stands for 30 minutes anymore. I may walk away from some, but I waste a lot less time.
Please pardon the ramblings of a thoroughly demented coyote calling enthusiast.