These antelope were seen enjoying a hayfield in Fort Rock, Oregon which is in northern Lake County. They are also known as the Pronghorn. They have no close relatives, but are related to cattle, sheep, goats,and Deer distantly. Unlike deer they have a gall bladder, and are also reputed to be among the fastest land mammals allowing them to outdistance their predators.
Additional information: see Wikpedia - Pronghorn