These guys are hard to find because they sink into the mesh underwater. I recommend flying over the swamp with an argy looking for any signs of movement or sails. Sometimes they’ll be on the shores of the swamp, too, so check there.
Once you find one, pick it up (if you’re on an argy) and take it to a safer place. Otherwise, just kill any dangers in the area and chase it around with your tranq method of choice. Use their huge turning radius to avoid their bites.
Once tamed, level melee to increase their insulation. Good luck!
Please. PLEASE don’t make the same mistake I did. I spent 30 minutes raging and chasing these guys down on my argy in THE SWAMP, trying to pick them up. Then learning you can’t pick them up with argies on mobile, even though the DODODEX says they can. When you can pick up raptors and kapros and an abundance of other things that are bigger than a dime