Don’t build a trap. All you need to do is shoot and run the’er really slow. And eventually they start torpor running so you just chase and shoot them till they fall over. I knocked out a lvl 115 and a lvl 95 that way at the same time Cause they both agrode on me. I probably should have killed one first.
get on a nearby hill or rock and kill ones you don't want as they usually spawn in 2s or 3s (recommend an argentavis). then start shooting the mammoth with tranquillisers. when it torpor runs finish it off, they are very slow so very easy to hit. (protect from dire wolves, yutiranus, etc....)