Thank you so much for the advice.
My husband, a nurse, and I have irrigated the wound with sterile saline and applied antibacterial ointment. Hubby tried to push the skin flap back but it appears that the skin has bunched up because much of the scalp is missing. I'm now thinking maybe a bird of prey snatched him but didn't finish the job.
Bird is eating well and is quiet but alert. We will continue cleaning him up and hope for the best.
Thank you!