I was coming down the main trail when I heard a big crashing noise on the hill above me. I stopped to see what I could see, and another park regular came up the trail and stopped also. It would be quiet and then there would be crashing again. At some point we saw Turkey Vulture wings, so we figured it was either a fight or a bird tryst.
Seeing the photo with the vultures head-to-head said 'fight'.