A courtship clash of 50-ton whales, violent enough to draw blood, has been hailed by naturalist Andrew Stevenson as the most compelling evidence yet that humpbacks are breeding in local waters.“It’s off the charts in the six years I’ve been studying the whales,” Mr Stevenson said, of the battle he witnessed among four males for the attentions of a female humpback. “It’s absolutely new. I suspected they were breeding and calving here, but this is the first time we have seen the behaviour consistent with breeding that we see in the Caribbean.”Remarkably clear, calm weather in recent days allowed him to observe the two-hour struggle in waters 25 miles off Bermuda’s coast.Whales rammed, headbutted and slashed at one another with their flukes, strongly enough to move Mr Stevenson’s Boston whaler all vying for the attention of the female.Now, he said, news of the Bermuda sighting is “going viral” in the global scientific community. Many scientists, he said, still consider the Island simply “a navigational way-point” for the animals,“It’s seen in the Caribbean but this is absolutely the first time anybody has seen breeding behaviour in what is essentially the middle of the ocean.”Mr Stevenson said it was evidence of a healthy return of the whales’ population.“They are staying here, not just travelling by here,” he said. “This is turning what we know about whale behaviour on its head.”