When trying to tame them be careful that they don't grab you off your tame because they cause stamina drain. Also on Xbox they glitch out and when they have you in there mouth they will 'runaway' but you will stay where you are but keep taking damage until you die. So you have to chase them down and kill it.
For all the noobs out there, if these things kidnap you in the swamp, here’s what to do. Take out your bow/ gun. Pray you have ammo and fire right into its head. This strategy has saved me countless times.
P.S. If you have a strong melee weapon such as a pike or sword on you, that also works.