It's not like I have a sign up saying "chicken dinner" - but we've had our share of predators. Your mileage may vary.
The foxes, dogs, and coyotes eat the guts and breasts, rarely a head. You might find the body, but if you do, it is usually sporting a broken neck (they grab and shake), and the body has been torn open and the innards are spread or gone.
The hawks leave my birds like yours - occasionally, they will hit them in an open field, but more often they hit them with the first strike, the hen runs for cover, and the hawk goes in after it (which is why we find them in the bushes.) That distinctive picking away at the meat and leaving the intact bones is the dead give-away for me. We have smaller hawks - Cooper's type.
Racoons, and like varmints, eat the heads off. The hawks leave the heads intact and pick them clean. Ugh, remembering my poor Ethel with nothing left on her neck but the bones....
Have never lost a bird at night (they are locked up tight), but I would expect owls would behave the same way as hawks.
So sorry you have lost a bird - it makes me angry and crazy and frantic!