Indian trackers were relentless in their pursuit of their quarry.  Pride and revenge was the chief motivators as they are with everyone else in the world.  The pursuers had the ability to carry on even under the worst circumstances.  These fellows are after some guys who have taken to tall timber in their hope for evasion and escape.  The trackers read the signs like reading a map and will continue on the tail of the miscreants until they are caught or killed or both.  Probably both since hardly anyone surrenderd anyway.