The open-ness of The Carrs floodplain near Scarborough is what attracts many of our farmland bird species to nest here, but boundary features are important habitats too, none less so than the network of drainage ditches which form a distinctive element of the Vale of Pickering landscape. These wet ditches are an important heritage feature in their own right and have been managed routinely since they were dug over two hundred years ago.
Ditch management, by which we mean the regular maintenance regime, carried out in autumn, winter or early spring, consists of cleaning out accumulations of silt, weed and vegetation in order to keep the water flowing. This is not merely a necessary operation for ditches which carry water from the land to the river system but it also performs a valuable role in managing them as wildlife habitats.
Some, which are important drainage arteries, may need to be maintained frequently – sometimes every year if the silation, debris or vegetation build-up is rapid. Those that are best for wildlife are managed on a rotational basis every few years, perhaps one in five or one in eight. Diversity and timing are key. Ideally a farm area would have a range of ditch habitats at different stages of succession – some just freshly cleaned and others at various stages of re-growth – hence diversity of habitats. Sometimes even longer rotations can be accommodated. In this way species which prefer clear, open sites and those which need choked well vegetated ditches will always have somewhere to thrive. Management in the winter has less impact upon ecology as a lot of wildlife is dormant. It is also helpful to wildlife if ditches which are immediately adjacent are not all done at once, potentially removing food plants and shelter. Cutting the banks or cleaning out only one side of a ditch one year and the other side the next, leaves undisturbed refuges.
Some of the best ditches for plants and invertebrates on The Carrs though are those which have an unusual origin – and the clue may be in the shape of the ditch. look on a map of The Carrs and you will readily identify lots of straight blue lines where artificial drainage ditches were cut when the large scale land drainage began after the 1800 Muston and Yedingham Drainage Act. This is the act of Parliament which paved the way for ‘the draining of the low grounds’ and the straightening of the Hertford and the part of The Derwent. At that time many subsidiary ditches were cut, draining into the New Cuts of the rivers. However in a few places there can still be found sinuous ditches which are relics of the former natural course of the Hertford. These older watercourses harbour some of the more notable wild plants and animals and may have greater ecological variety. Plants such as Water Violet, Water Whorl Grass and the primitive stoneworts are found in such places.
An Internal Drainage Board oversees the water level management of The Carrs including The Hertford Cut. Currently there are three IDBs in the Vale of Pickering (with Muston & Yedingham IDB being our local one) but they are preparing to amalgamate