The March 2017 issue incorrectly identified the animal on its cover. The rodent pictured is a Wyoming ground squirrel, not a black-tailed prairie dog. Although similar in appearance, Wyoming ground squirrels (Urocitellus elegans) and black-tailed prairie dogs (Cynomys ludovicianus) have distinct features that can help identify these animals in the field.
Wyoming ground squirrels are smaller in size (approximately 10–15 oz.), with longer tails and more prominent ears than black-tailed prairie dogs. Another helpful characteristic is the animal's coat. Although mostly gray, Wyoming ground squirrels have reddish accents above their nose and on their limbs.
A black-tailed prairie dog's coat is more uniformly colored, aside from its namesake: the black tail. They are larger (approximately 20–55 oz.) than Wyoming ground squirrels, and they have a more complex social structure, as described in the March 2017 issue. Black-tailed prairie dogs also prefer flatlands at elevations below 10,000 feet, where they establish large colonies in short or mixed grass prairie. Much of Rocky Mountain National Park (where the March 2017 cover photo was taken) is unsuitable habitat for black-tailed prairie dogs.
For more information on Wyoming ground squirrels, you can visit the Rocky Mountain National Park website: https://www.nps.gov/romo/learn/nature/squirrel_chipmunk.htm
Or you can read the references cited below, which provide more specific information on where (and when) you might encounter this little mammal.