A worthy opponent

I love this photo, even it it is a bit out of focus.
I took it in the zoo while some vultures were bothering the lions. I was surprised that the vulture was pecking the lions' tail and fur, and even when this lioness get angry and turned against the vulture this didn't move.
That's when I took this photo, I still doesn't understand why the lioness didn't hit or bite the vulture being this so close, even after a while of staring to each other finally the lioness move to a tree nearby to avoid the vultures, who keep bothering some of the other lions.

That were some brave vultures indeed.