Use tranq arrows. It may sound dumb, but their torpor is way lower than their health. I got an egg by just knocking out three of them and teleporting away. WARNING: their torpor drains VERY fast, so you need to keep tranquilizing them while their asleep, or kill them while their knocked out.
If you get too close to a wild one that used it's special ability (a charge that will set it on fire and aggravate nearby dinos) it'll display a message saying "getting hot! Stay away!!!!" and that will set you on fire. Don't approach unless you know you're prepared.