Deer, belonging to the family Cervidae, are hoofed, ruminant mammals. Wyoming’s diverse geography, ranging from high-altitude mountains to sagebrush flats and river bottoms, provides a home for two distinct species of deer. These animals are a significant part of Wyoming’s wildlife heritage, drawing the interest of naturalists and sportsmen alike. The differences between these two species result from evolutionary adaptations to their specific environments.
The Iconic Species: Mule Deer
The Mule Deer (Odocoileus hemionus) is the most widespread deer species in Wyoming, adapted to the rugged terrain of the American West. Its name comes from its large, mule-like ears, which are approximately three-quarters the length of its head and help detect predators. The coat color changes seasonally, from reddish-brown in summer to grayish-brown in winter.
A Mule Deer’s tail is a thin, rope-like structure that is white with a distinct black tip. This tail is surrounded by a large, cream-colored or white rump patch. Male Mule Deer possess antlers with a unique bifurcated structure, meaning the tines fork repeatedly as they grow, rather than rising from a single main beam.
These deer are commonly found in arid and open habitats, including sagebrush plains, high-elevation alpine zones, and mountainous areas. When startled, Mule Deer employ a stiff-legged bounding gait known as stotting. This four-footed jump allows them to quickly cover uneven ground and gain a vantage point to assess a threat.
The Eastern Presence: White-tailed Deer
The White-tailed Deer (Odocoileus virginianus) primarily inhabits the eastern and northern portions of Wyoming. This species prefers habitats offering dense cover and moisture, such as riparian corridors, wooded stream drainages, and brushy areas, often utilizing agricultural lands for foraging.
White-tailed Deer have smaller ears and are generally smaller in body size and weight than Mule Deer. Their antlers feature a main beam that curves forward, with individual tines rising upward from that single beam. The tail is broader and bushier, lacking a black tip.
The bright white underside of the tail gives the species its name. When sensing danger, the deer raises and waves this tail like a flag.
Identifying Differences in the Field
Distinguishing between the two deer species relies on observing physical traits and behavioral patterns. The tail is the most reliable feature for initial identification.
The Mule Deer’s tail is a thin, rope-like appendage with a black tip and a large white rump patch. In contrast, the White-tailed Deer has a broad, brown tail with a prominent white underside that it raises and waves when fleeing.
Antler structure provides another clear distinction: Mule Deer antlers are bifurcated, forking repeatedly. White-tailed Deer antlers have tines that grow individually off a single, forward-curving main beam.
Mule Deer possess noticeably larger ears. Finally, the manner of movement when alarmed offers a consistent clue. The Mule Deer uses a distinctive stotting or bounding gait, whereas the White-tailed Deer runs with a fluid, traditional galloping motion.