The last time I was down at the American River they had set up an impressive amount of temporary fencing around an impressive number of goats for a fire control project. I didn't take the time I should have to get a picture that conveyed the muchness of the goats.
But a little further into the park, there was a fine example of their effectivity. This view is looking over one side of the trail, left in its natural condition:
And this is the view in the opposite direction, where the goats had been pastured only a day or two before. And yes, the trees were bare of leaves as high up as a goat might reach. They're definitely good at what they do.