Turn around and walk backward about ten feet every time you feed it berries then turn back around and see which way it turns and then sneak around it, feed it berries,repeat EASY TAME (by the way remain crouched the whole time and have LOTS OF PATIENCE!!!)
Always stay crouched while taming. And never get close enough to touch it. While following the monkey, if the monkey ever stops, its very likely It will turn and start to walk in a different direction. So be aware that it might walk in your direction. Hope this helps : )
I tamed 37 of these with mejoberries. No crouching or crawling or even ghillie. Just simply feed ONE dodo kibble or be very careful and approach from behind. They are an adorable tame, and can equip hats!