Dire bears have the same base torpor and torpor gain per level as an allosaurus, meaning darts are almost a requirement (unless of course narco traps are utilised). To put this in perspective, Allos have 63% more base health than a dire bear and gain more health per level, and even with a lvl 150 allo there is still a 1.5% chance that they’ll die for a 100% damage Crossbow. In summary, use darts, it makes it a hell of a lot easier.