I've found him every time walking along the beach of the redwood biome. What was mentioned earlier works, build a stone trap. One foundation 4 door frames get him to chase you in then seal it. A random sabertooth tiger showed up during my tame attacked him and reset my timer, so beware.
Easy to tame, just sneak and bring one soothing balm and berries but i prefer mejoberries. If your looking for one of these go to the redwood forests and you might find one just search for it, but becareful the terror birds might attack you or purlovias the sneaky rat. (Up if this is helpful)