A large skid loader will move round bales that weigh 1500#. I move round bales with a skid steer using a bale fork. It is a Bobcat with a Kubota and designated as a 763. It is marginal at best and if the bales weigh more than 1200# it gets pretty prone to tipping. If there were 1500# bales to move you need about 2000# lift capacity, especially on uneven ground. A skid loader is better moving pallets around than a tractor simply due it its tight turning radius.
I would not move round bales with a tractor that had less than about 75 hp. You can do it with a smaller hp tractor but not over the long haul, at least in my experience. .
