It takes years of experience and practice to spot tracks from a moving vehicle, especially ones not as fresh or obvious as these.
Teamwork
Half the fun and much of the success of hound hunting comes from working as a team. In Bob's case, he and his partners break up in the morning to scout out different canyons in the area. When Bob or one of his partners finds a track, the rest are notified. No one lets his dogs loose until everyone arrives.
After the chase begins GPS allows everyone to track the position of their dogs and help each other out when necessary.