Background information and definitions
Managing ditches to benefit wildlife can involve reduced or delayed cutting of vegetation on ditch banks and restricted fertiliser, herbicide or pesticide use on ditch banks or in fields adjoining ditches. ‘Bunded’ ditches are blocked to allow them to fill with water.
Supporting evidence from individual studies
A replicated, controlled and paired sites study of bunded and non-bunded drainage ditches in arable and pastoral areas of Leicestershire, UK (Defra 2007), found that bird visit rates were significantly higher in bunded compared to non-bunded ditches (1.0 vs. 0.5 visits/month). Sampling involved bird observations (45 minutes, 1-2/month between April 2005 and March 2007.Study and other actions tested
A replicated 2010 site comparison study (Davey et al. 2010) of the same 2,046, 1 km² plots of lowland farmland in England as in (Davey et al. 2010) found that three years after the 2005 introduction of the Entry Level Stewardship and Countryside Stewardship Schemes, there was no consistent association between the length of ditches managed according to the agri-environment scheme on a plot and farmland bird numbers. Although there were higher numbers of linnet Carduelis cannabina and reed bunting Emberiza schoeniclus (two species known to nest in vegetation at the side of ditches) in plots with ditches managed according to the Countryside Stewardship Scheme and Entry Level Stewardship than in other plots, this difference was not observed for other species also expected to benefit from ditch management, including the yellowhammer Emberiza citrinella and yellow wagtail Motacilla flava. Between 2005 and 2008, skylark Alauda arvensis and grey partridge Perdix perdix declines were greater in plots with lengths of ditch management than other plots. For example, grey partridges showed decreases of 1.3 birds for each 0.08 km of ditch on pastoral farmland. The 2,046 1 km² lowland plots were surveyed in both 2005 and 2008 and classified as arable, pastoral or mixed farmland. Eighty-four percent of plots included some area managed according to the Entry Level Stewardship or Countryside Stewardship Schemes. In both survey years, two surveys were conducted along a 2 km pre-selected transect route through each 1 km² square.Study and other actions tested