No, he wasn’t yodeling… don’t worry, I thought that too, at first. However, I do believe he was attempting to cough up a nice juicy Caracara pellet. Yup. They do that. He never produced anything, but this "yawning" type movement is a good indicator of that particular action.
Taken with a Nikon D80 and 70-300mm VR AF-S Nikkor Lens set at ISO 100, 1/200 F10 at the Viera wetlands, viera Florida