At first I thought the grey-blue, rather stiff-winged bird was a collared dove. But there was something a little too quick and purposeful about the flight. The flight became even more rapid as the bird swooped low over the ground. Express wing beats were punctuated by a full-tilt glide that shot it round an oak tree and into a small flock of sparrows in the stubble. It was a merlin, our smallest bird of prey. His deadly flight proving fruitful, the falcon took up his catch to be plucked on the nearby electricity pylon. At that height his colouring appeared even bluer; no wonder people used to call the merlin the blue falcon, although the females are brown. All hawks and falcons have their tactics. The sparrowhawk skims along hedges and snatches roosting or resting birds. Kestrels hover an