I’m at a loss for words here. I have no idea what’s happening above my head. My first thought was that the raven was smacking something against a tree branch, possibly an oyster shell (oysters are plentiful in the area and popular corvid-food). Listening back, however, it’s clear this is an internally-created sound from a raven. Snapping its beak? There’s a little “gulp” sound it makes occasionally that makes this a viable conclusion.
The recording’s a bit noisy because of distance, so I’ve included a noise-reduced version immediately after that enhances the details, but loses some of the beautiful reverb of the trees.