One of these days I will compile a list of the fascinating things I have seen in car parks. Last weekend, on the road with my ceilidh band, we pulled into a market town for a fry-up. Leafless with winter, tall lime trees towered over the parked vehicles. Taking in a deep breath of cold air, we noticed a snag of shaggy greenery near the top of one of the limes. Being northerners none of us had seen mistletoe before – it grows most abundantly in the Welsh borders and cider counties of the South-West – but we knew it could not be anything else. What was it doing in a Yorkshire car park? Having been a largely sedentary plant for centuries, lately mistletoe has been on the move. And it is all due to the changing habits of a little warbler with a big voice, the blackcap. Once migran