Nonviolent methods often require the possibility of violence as a backdrop to be effective. Otherwise, they might not yield the desired results.
While Gandhi's philosophy sounds nice in theory, it may not always be the most practical in real-world scenarios.
You probably meant that the animal kingdom follows the law of the strongest, or "might is right".
Time to post that legendary soundbite from Starship Troopers, I guess:
One girl told him bluntly: “My mother says that violence never settles anything.”
“So?” Mr. Dubois looked at her bleakly. “I’m sure the city fathers of Carthage would be glad to know that. Why doesn’t your mother tell them so? Or why don’t you?”
She said shrilly, “You’re making fun of me! Everybody knows that Carthage was destroyed!”
“You seemed to be unaware of it,” he said grimly. “Since you do know it, wouldn’t you say that violence had settled their destinies rather thoroughly? However, I was not making fun of you personally; I was heaping scorn on an inexcusably silly idea—a practice I shall always follow. Anyone who clings to the historically untrue—and thoroughly immoral—doctrine that ‘violence never settles anything’ I would advise to conjure up the ghosts of Napoleon Bonaparte and of the Duke of Wellington and let them debate it. The ghost of Hitler could referee, and the jury might well be the Dodo, the Great Auk, and the Passenger Pigeon.
Violence, naked force, has settled more issues in history than has any other factor, and the contrary opinion is wishful thinking at its worst. Breeds that forget this basic truth have always paid for it with their lives and freedoms.”