The Coues Whitetail is a small subspecies of white-tailed deer found in Arizona, New Mexico and Mexico. Many people consider Coues deer to be the most challenging big game animal to hunt.  Some even refer to hunting Coues deer as the "poor man's sheep hunt" because of the harsh terrain involved.  Famous big-game hunter Jack O'Connor proclaimed the Coues deer to be "the most difficult of all deer to kill" due to its extreme wariness and the inhospitable habitat this deer can live in. 
As many guides will tell you, they want clients that are able to shot long distances because the bucks they spot may be far across a canyon.  And quietly stalking to that far side of the canyon may be impossible due to the rocky soil and thick brush that is found in Coues country.

The Coues deer varies in color from a grayish coat in winter to a more reddish-brown color in the summer. This deer has developed such a reputation for being able to vanish from view in the smallest amount of cover that it is frequently referred to as the "Grey Ghost".