DO NOT use a crossbow for knocking out! Not for all shots anyway.
Use half to 60% of what Dododex recommends for crossbow, then finish the rest with harpoon tranq to avoid killing these guys.
I feel like Dododex is way off with their approximation of a 19% chance of death with a crossbow tranq. I'd say it's more of a 80%+ chance you will kill these with tranq only.