Hay harvesting causes high orthopteran mortality

Knowledge on the direct impact of the meadow harvesting process on field invertebrates has long been limited to studies that investigated impacts due to mowing. This study demonstrates that raking coupled with baling impacts orthopteran populations to a similar degree as mowing followed by tedding. At the end of the harvesting process, orthopteran surviving rate was 32% (SD = 14) when meadows were mown with rotary mowers without conditioner and lower, 18% (SD = 8), when mown with rotary mowers with conditioner. Conversely, given the strong impact of tedding, raking and baling, no evident advantages were found for the use of tractor bar mowers over rotary mowers without conditioner. Reduction in orthopteran densities observed after harvesting was slightly higher than the estimated mortality caused by the machineries, presumably because orthopteran reduction includes a small emigration and natural mortality. If conservation is the primary objective of the meadow, no conditioner should be used, uncut grass refuges should be left when mowing, and the number of time the meadow is harvested per year should be the minimum required to maintain the habitat. (c) 2010 Elsevier B.V. All rights reserved.