A Country Diary: Old Denaby

As dusk gathered over Old Denaby wetlands, small birds dropped in to the reed beds to roost, blackbirds shot across the open areas, cuckling as they went, and half a dozen magpies argued, first among themselves and then with a lone carrion crow.

This huge wetland, tight by the River Don, is suffering from the lack of rainfall affecting the rest of the countryside; large exposures of bare mud and silt are bright green with vegetation, so long have the water levels been low. It will take more than a day's steady rainfall to fill these pools.

In the distance, some birds were flying differently. Closer inspection, through binoculars, revealed them to be bats. Three of them, quite large, were high above the open water in straight lines; then they suddenly plunged as prey was taken, perhaps a loop up to the original flight path, then back on patrol.

They were probably noctule bats, which roost mainly in trees, and often fly more than a mile to their feeding grounds. Open water is a favourite haunt, but their high flight distinguishes them from Daubenton's bat, which hunts low over water. Noctules are also noted for their early emergence from their daytime roosts, and, despite the dimness, it is still only 4pm.

We shall pass this information to the local bat workers. The time of day and year will be of interest, and, in a tiny way, will help our understanding of what makes bats tick.