Is there a word for motion that a bull makes when it kicks back with his legs before charging?
Solution 1:
The entry for paw in the AHDL includes:
2. To strike or scrape with a beating motion: The bull pawed the ground before charging.
From an article on a UCB site by a professor of veterinary medicine titled, Why and how to read a cow or bull:
The direct threat is head-on with head lowered and shoulders hunched and neck curved to the side toward the potential object of the aggression (Photo 2). Pawing with the forefeet, sending dirt flying behind or over the back, as well as rubbing or horning the ground are often components of the threat display (Photo 3).