Escape gaits of white-tailed deer, mule deer, and their hybrids: body configuration, biomechanics, and function

Characteristics of body configuration in the escape gaits of white-tailed deer, mule deer, and their hybrids were examined to evaluate mechanical features of these gaits that pertain to their function. Landing and takeoff angles, angles of limb and vertebral flexion, and neck and back attitudes were calculated using data digitized from high-speed films. Galloping white-tailed deer had the most horizontally directed flexion in their necks, backs, and forelimbs. Combined with features of limb timing, the summation of velocities of these body segments results in a faster gallop for white-tailed deer than for galloping mule deer and hybrids. Stotting mule deer attain considerable horizontal velocity which may be conserved between strides. The bound, used by hybrids, appears to be a slow and mechanically inefficient gait for deer, primarily due to biomechanical factors stemming from the coupled forelimb landing and associated steep body position. These limitations present the possibility that hybrids have ineffective responses to predators, which could lower their viability relative to that of white-tailed and mule deer.