So... I have to raise a few points here. I'm still flexible and I still could be wrong...
I have experienced both bird of prey predators AND dogs in the neighborhood being culprits. When it was dogs that attacked my birds, there was always remains, blood, viscera around right where they were grabbed every single time. Every dog attack this was constant. A dog is 'more likely' (but not guaranteed to) also start 'dismantling' right there.
But with the bird of prey 'incidents' there was no sign of anything at all. No blood on the ground. Nothing to track. Birds of prey tend to carry it off somewhere safe away from the ground before they start eating.
...