To the casual observer, stands of dead reeds and/or reed canary-grass, on wetland fringes, may look unappealing. Bleached almost white, flattened down by autumn winds, lying in a boggy ooze of mud, what interest could there be in November? The answer is harvest mice. Not the tiny individuals, but the remains of their summer nests, balls of stripped leaves woven between stems, lined with soft downy seed heads, they are clear evidence of a breeding population.
At Harthill Reservoirs, a series of three header tanks built to maintain water levels in the Chesterfield Canal, we searched carefully through the jungle of still stems. Moving slowly, carefully parting the stems with our arms, peering intently, we worked our way through each stand of reed canary-grass.
Our mental picture of the harvest mouse is of an acrobat, clambering amongst the ears of corn, its ball of a nest suspended between the stems. In fact we find more evidence of them in the sort of marginal wetlands we were searching. Of course, we rarely get the opportunity to search through standing cereal crops. They were often only seen at harvest time - hence the name.
Right up until relatively recent years they have been regarded as scarce and thinly distributed. Now we know a little more about them, we can look at likely sites after the summer breeding season, record their presence or otherwise, and all without disturbing the animals we are keen to encourage. The nests are there but the users long gone to drier winter territories. They are still not common, but probably more widespread than we thought.
Our quest was rewarded with the discovery of two nests, both about two feet off the ground and in a fairly bedraggled state. There are only small stands of what seems to be their favourite nest building plant, reed canary-grass, and with the levels of disturbance from humans around the water's edge it is not surprising they are few and far between. For winter survival, the tussocks of coarse grasses, holes, nooks and crannies at the base of willows and alders are most important and make the reservoirs area so valuable.
