A sharp wind scoured the fields. The afternoon was lengthening. Heading for home, a raucous cacophony began behind me. It grew louder: a flock of rooks was making for its winter roost. One after the other, the birds tumbled overhead. Their “bottom of the piano” calls were far from musical but there was something uplifting about the din. Although hard to tell from the near-identical carrion crows, rooks are very different. Unlike carrion crows, they’re irrepressibly sociable, nesting and wintering together in the same large tree- top groups. Neither do they feast on roadkill and carrion, but specialise in worms and insects. Maybe this is why, while our collective noun for carrion crows is a “murder”, we call groups of rooks a “parliament” or a &ldq