Use a flyer (preferably argy or similar weight) fly above try not to aggro and place spikes around him quickly pinning him in, I've noticed they react to the walls even before placing fully, then just find a gap to poke your hand in :) this way I done this easily the first day they came ;)
To those of you who wanna tame these suckers with stimberries, DO NOT DO THIS! On official servers the get only 0.1% per feed so recommended to NOT try stimberries or at least until you have some soothing balm. Upboot if you found this helpful
For beginners these things will spot you in a split of a second so don’t even think of going up to it with a stimberry in your hot bar. Instead, get a ghille suit and sneak behind it and feed it a beer! Don’t use stimberries it is pain And time consuming unless you have a bush of stimberries. They eat berries after they are tamed though. Not beer.