None of the cows had any marks on their backs that aggressive males might have left behind, they said.

It was one female, fighting off the advances of an aggressive male.

It may as well be the aggressive, testosterone-pumping, hunter male.

An aggressive male will crawl toward an intruder with his neck extended.

But her second son, Frodo, a very large and aggressive male, showed no such inhibitions.

But young, aggressive males usually respond much faster than anyone else.

The bad news is that you might have to first knock out all the most aggressive males to get there.

And mating with a more aggressive, competitive male may increase the female's risk of being harmed.

The higher age in the wild may reflect that females need to be large enough to avoid being killed by the aggressive males.