On our server we have too many people building around green but the best spot I have found is west of red tower to the river with three water falls, just go up to the second and I've never left empty handed, I personally own 17 and I'm working on my 4th generation of mutations!
If your on mobile and can’t find one of these guys start the tame equus pursuit and walk or fly around the island and eventually a arrow will show up on the top left of your screen. If you follow that then you will find an equus or two. Upvoote if you found this helpful.
Put this higher !!So if you play mobile I found 3 in the same spot okay so first do the volcano pursuit the one where it's the cave inside the pursuit should be south of the equator and in that general area if you look around you'll find them