Leaping bison, snorts, and thundersous metallic kicks bounce off the metallic coral walls as American Bison (Bison bison) file into a zone called "the tub." A gate closes a group of about 10 to 20 bison in the tub at a time, a scene of carefully controlled chaos. Ranchhands use flags, rattling paddles and shock sticks to direct individuals towards the first gate in a series of chutes that lead up to the vaccination station. This is a sensitive time of the process, trying to keep the animals moving and calm during an otherwise stressful experience. Adult males have been kept out of the roundup to help protect babies and young bison. Bulls can become aggressive in tight quarters, sometimes goring or trampling smaller individuals.