Clearly the creators of the Roadrunner cartoon (Warner Brothers) had never heard a Greater Roadrunner. They most definitely do not sound like "beep beep." I hear it as a sharp hooting squawk (but listen for yourself at the link above). Coyotes don't hunt them, not even with Acme devices. They do prefer to run, though; they can fly short distances, too. Note how well camouflaged they are against the ground and the mesquite.