These goatlike Rahi live on top of the mountains, so few Rahi can reach them. BKKKN eats mostly plants. They are not agressive at all, though in dangerous situations their horns can be serious treat.
Matorans tried to tame these creations, but being captive these Rahi don't eat and die.
Their strange name was given because of the sound they rarely made (it similiar to "B-k-k-k-k-k-n").