Every year a few molehills appear in our fields, usually in clusters, which I’m told are due to single moles setting up runs and ‘worm-traps’. For a year or two I recorded the distribution of the clusters and found that they were not concentrated in any particular area, so either moles move on or die, or else they stop once they have set up their runs. Our lawn, too, is mole-ridden and, although the molehills are raked out, the ground is actually a dense network of mole runs just below the surface.
This year the moles have surpassed themselves, turning most fields to a state that recalls the worst attacks of childhood chicken-pox. During the repeated snows on January and February, we were forcibly reminded of how many there were when we tried cross-country skiing – which is hard enough anyway, and doubly so when one hits frozen mole hills repeatedly. We were also treated to displays of molehill digging as we skied – fresh mounds appearing above the snow as we stood there.
The sheer number of hills moved me to work out how much ground they cover. Using a tape and random transects, I calculated that molehills occupy 24% of the ground in the densest clusters. They must depress grass productivity and they are a menace to haymaking, and so they will be scarified out shortly, but they help the flowers by providing fresh germination sites. As happens so often, the greatest biodiversity is associated with conditions that are not ideal for farming.