Shows the location of all nearby beasts on the minimap. Only one form of tracking can be active at a time.
Track Beasts is a Hunter ability to track the Beasts that are in your immediate vicinity. This allows one to either follow a Beast with the intent of killing it, or finding a safe path through the local area mobs to minimize aggro; as in the case of having to escape from a fight turned sour. One may hover their mouse over a target on the minimap and get a minimal description.
Docile beasts appear as yellow blips. Beasts represented by a red circle inside a yellow frame are aggressive creatures that will attack if you venture too close.
It is useful when trying to track a rare beast with a specific name, to warn of incoming powerful beasts you don't want to meet like the Devilsaur, or keep an eye out for any Druid trying to sneak up on you in Cat Form in a Battleground.