What’s goin’ on here?

Lunge

Usually in intermale interactions, one stallion rearing and propelling himself forward by pushing off the hind limbs, effectively charging toward the opponent.  Can be in a  sparring and playful manner as depicted in the top line drawing, or with more aggressive manner and bite threat as in lower drawing.  May be part of an extended sequence of intermale sparring or serious fighting, or as depicted in the wintery scene, may be a sudden discrete aggressive gesture.