I view the Red Fox as different as I do the coyotes. Many Red Fox will dismiss ambient noises when a hunter draws near. Specifically deep base noises. However, they are greatly tuned into high pitched noises. Never say never; However, some Red Fox will pay attention to most area noises & will go into alert mode, like a Coyote. Speaking of coyotes to many hunters. I believe they believe coyotes are not all that wary to area noises. Those hunters are foolhardy to believe that. Coyotes imo have some of the most keen senses & remember those distant or close noises. Which puts them into alert mode. Whether I stalk one that is bedded down or sneak into a call area. I do my best to remain hidden from their view & silent like a cat stalking a bird. As I draw near them. Both canines use the up wind areas. As a primary area to get from one down wind area to the next. Whether it be flat or hilly terrain.