Shoot for the head or tail with trans arrows and crossbow combo. When it rolls into a ball leave the area and keep an eye on them with a spy glass. Wait for it to start moving before approaching and shooting again. For high level ones, use a magnifying glass to check the torpor lvl while it's in ball form. Takes several rounds to get them knocked out. Don't waste your time trying to apply torpor while it's in a ball. Good luck.
So much misinformation here. Where to begin lol ok so as of Aug 2023, you can knock out w tranq arrows no problem, just go for level 80+ shoot in the head not the shell, wait 5 seconds between shots. You can’t bola them so ignore that comment. Creatures do not take torpor damage when they are caught by bear traps so ignore that comment too. Someone said to use biotoxin to keep them unconscious that’s a terrible plan because these guys wake up pretty fast, and they take quite awhile to tame high levels. You want to use narcoberries because they take the longest to take effect, the time it takes to fill up all the way is invaluable compared to filling it up fast.