Found this pigeon down a dirt alley that was sat on floor doing nothing. We stopped to not scare it, but after about 30 seconds it started to roll its neck back in such a way I could only describe as a those it was possessed, and then it tried to fly, but into the ground. After first I thought it looked totally drunk, as though its eaten some old fruit and now can't figure out anything. It then puffed itself up, sat calm, and after another minute tried to fly away, but again just into the ground. It's neck didn't seem broken, nor a wing (based on it trying to fly off and both wings flapping seemingly fine). We decided to try put it in a pot we had, but was too small and the pigeon kept trying to walk off. Knowing it was vulnerable we ended up picking it up and carrying it home, but again it started to have that possessed neck action going on so put it down and it did the floor flying thing. Left it for the next 5 minutes. Breathing got heavy and it ended up taking once last breath and then drying. Hoping someone might recognise this behaviour and the cause? I'm more curious than anything else.