Lead the Alpha into the Swamp nearby. The giant crocodiles will fight him, giving you time to escape or snipe him with poison arrows.

You cannot tame Bigfoot using standard passive methods. He must be captured by force. To do this safely, prepare your inventory at your workbenches with specific tools:

Do not approach Bigfoot with standard lethal weapons. If you reduce his health to zero with traditional blades or arrows, he will die, wasting the encounter. Mad Island - How to tame Bigfoot

Unlocking the Beast: How to Tame Bigfoot in Mad Island In the chaotic survival world of Mad Island