Not sure why everyone discourages taming. I'm pretty sure the game replenishes their numbers every time the server goes through a wild dino wipe, and these little guys are really handy to have around for what little space they require.
The method I used to tame was picking up the beaver with my crystal wyvern and dropping it in a taming pen. Pretty easy knockouts but their torpor drop rate is INSANITY and you can't leave then for more than 3 minutes. Feed them either mejoberries or crops (kibble is really expensive but if you want to do that, go for it).