First, you must bind the whistle to the bison. Shift-click the bison with the whistle to the bison. You can only bind whistles to bison that you own.
To call the bison, use the bison whistle with right click.
Bison Whistle also has a crafting recipe. It's a bit expensive in the early-game since it requires diamonds. Here it is:
Bison whistles have a chance to spawn in Nether Fortresses, End Cities, or Strongholds.
Bison Transfer Edit
Bison whistles can also be used to transfer a flying bison from one owner to the next.
- Bind the whistle as described above
- Give the whistle to a friend
- Have the friend use the whistle
- Press L on your keyboard to confirm the bison transfer