The winter sun was setting when the wood pigeons lifted from the woods. A hundred, two hundred, three hundred of them. But instead of flying out over the acres of rapeseed in a chaos of clattering wings, as I have seen them do so many times before, they formed a single flock drifting gently above the trees. The flock then wheeled violently, turned in and out of itself, shrank to a thick, black density before bursting out into a looser formation again. It was a murmuration – the name we give to those huge, pulsing groups of birds settling down to roost. Until now I thought only starlings behaved like this. All at once the wood pigeons took on the shape of a dolphin, then a giant fish, before lapsing back into just a huge, fluxing flight. To us, wood pigeons are clumsy, almost comical