A wild herd of mustangs ranges near Miradero. It was protected by Spirit up until Spirit left the area with Lucky to join El Circo Dos Grillos, at which point Spirit's role was taken over by Smoke, a rival mustang in the herd. The size of the herd varies, but, exclusive of Spirit, it has been shown as consisting of as few as ten individuals (early on), as many as fifteen individuals (after the birth of Governor), and down to twelve individuals (after Smoke took over).
Lucky first spotted the herd early the week of the bazaar, in her first spring back in Miradero, and encouraged Spirit to run with them, while she walked back to town, making her late for school. Later that week, Abigail's horse Boomerang developed a yearning to run with the herd, and broke out of the round horse pen nearest the schoolhouse to fulfill his dream.[1]
On Christmas morning of Lucky's first winter back in Miradero, the PALs brought bales of hay to the herd to feed them.[2]
The next spring, the PALs noted a pregnant mare in the herd, but Smoke would not permit them, or Mr. Granger later in the day, to approach. When the mare began a troubled labor, Spirit fetched the PALs, who helped deliver a new foal Abigail named Governor. Spirit had to fight off Smoke to allow the girls access to the mare.[3]
Later that same spring, the PALs surprised Aunt Cora by bringing her on horseback to see the herd on Punta Libre. Earlier the same day, a mountain lion had attacked the herd, wounding Governor and killing his mother. Later in the day, with an electrical storm approaching, Spirit tried to gather his herd for shelter and defense, but the herd stampeded and Spirit was gravely wounded facing the mountain lion alone.[4]
When an earthquake struck Miradero later the same spring, Spirit was with the herd just outside of town. At that time, the herd consisted of twelve adults and a young gray foal (not Governor). During the temblor, Spirit rescued the foal from a falling pine by urging him out of the way just in time. Later in the day, an aftershock struck while the PALs accompanied Spirit to check up on his herd. The aftershock caused the herd to stampede away.[5]
Eventually, Smoke challenged Spirit for the role of protector of the herd, and, after several unsuccessful attempts at doing so, Spirit relinquished the role to Smoke to join Lucky in the circus far away from Miradero.[6][7] When they finally returned to the area several months later, Spirit seemed disheartened that the herd had taken well to being protected by Smoke and appeared not to want to re-join the herd.[8]