Racking is what a bull does during the rut. You'll see it on birch and maple, and some of the pines, spruces and balsam if the tree is bare enough of branches. Usually the diameter of the tree will be about 1 or 2 inches, something they can easily bend while they trash at it , or in other words, be dominant over. Racking usually leaves the bark shaggy when they're done.
As for feeding, what the animal will do is nip into the bark of a maple and pull. The bark comes off in long clean strips leaving the bare wood exposed. This may account for what you're seeing as being a bit high as they nip three or four feet from the ground and then pull upward until the bark breaks off. Usually the tears are clean and if you look closely, you'll see the marks of their teeth near the start of the pull. You should also recognize moose feeding on dogwood or young maple. This is really easy because they nip the tip off and almost always leave a small tendril of bark about 1/2 or 3/4 inches long on one side. Moose have little in the way of upper teeth so they bite through the twig, then pull, leaving that sliver of bark.
Your next lesson, try to learn the difference between bull, cow and calf droppings. Don't use the taste test method though :-) Now, one other thing to consider, bears will strip smaller diameter trees of foliage in a similar manner. They'll straddle the tree until it bends far enough over then peel the leaves off. This is common in the spring when leaves are new and still succulent.
