These guys are relentless! They will chase you like you own them money if you open the inventory of their dams. Your best option is to take everything in the dam and let yourself die and come back for the loot.
Outstanding wood collectors. Mine has 770 weight and can carry 3K wood plus rider. Holds wood at 1/5 weight and can be used as mobile smithy. This teamed with a doed can construct a base in minutes. Must have.