How does buck perform when he replaces spitz as the lead dog?

Buck excels at leading, whipping the rest of the team into shape. Buck forces Pike to carry his share of the load, and he soundly punishes Joe for his bad behavior. At the Pink Rapids, they pick up two new dogs, Teek and Koona, and Francois is astounded by how quickly Buck breaks them. They make record time back to their starting point, and the whole team struts proudly through the town.

Buck quickly achieves mastery over the other dogs. He loves to sit in front of the fire and dream. Sometimes he dimly recalls memories from his California home. More often, he is visited by visions of an ancient life, his place with ancient humans. He sometimes thinks he sees a man, different from men today, and he remembers the rustle of beasts and the readiness for the fight.