The new tenant in the old home farm here, facing across the duckpond, soon came to our front door. ‘You have an awful lot of carp in that pond’, he said, ‘would you like me to fish for good ones for you to put in your other pond?’ He didn’t know there are five other ponds, but now, a few weeks later, they all have grey submarines cruising, dreaming, occasionally scooting about; a lovely way of wasting time as we walk around the garden.
He rightly suggested only moving big fish – too big, we hope, for the heron who is on constant patrol. He sits on the improbably
fragile-looking top branches of birch trees, hour after hour. His body-weight must be tiny in relation to his height and wing-span – and leg-length. Our aim is the keep it that way by denying him any fishy feasts.
We all discovered in this village years ago that little ornamental fish in shallow ponds are an invitation the heron makes no attempt to resist. What precisely is the ratio of fish body-weight to water-depth to frustrate him we are starting to find out. A sharply shelving pond-edge is a start: no shallows to paddle in. The smaller fish we moved were snapped up; not yet the ones over a foot long.
Carp, of course, keep their water muddy by stirring up (indeed apparently eating) the bottom. Is it true, though, that the oily/milky cloud that floats on the surface when the heron flies off is a secretion from around his knees intended to attract the fish?