The other day, as I crossed the lake in St James's Park I stopped and rested my hands on the handrail of the bridge and it felt very cold - cold enough for me to put my hands back in my jacket pockets.  But in the water below me was a black-headed gull with an almost completely black head.  It seemed far ahead of all the other bhgs on the water or flying around.  It must think spring is closer than its mates do, or than I did that morning.  But there are robins singing everywhere and the occasional blackbird and song thrush, and the hazel catkins are making a bright show this year.  First sand martin a month away?