Wetlands support higher breeding wader densities than farmed habitats within a nature-rich farming system

Abstract

ABSTRACT Capsule Wetlands with little or no agricultural activity support higher breeding wader densities than more intensively farmed habitats within a nature-rich farmed landscape. Aims To test whether breeding wader densities differ between habitats likely to receive varying agricultural management intensity, within a nature-rich farmed landscape. Methods Using the island of Sanday as a case study for the wader-rich Orkney archipelago, a whole-island breeding wader survey was used to generate population estimates and test whether breeding densities differed between habitats under varying management intensities. Results The island supported nationally high breeding wader densities, which approach those of high-density areas elsewhere in Europe. Densities of total waders and five out of six species tested varied significantly between habitats. Wetlands subject to no agricultural management or livestock grazing in some land units supported higher densities than more intensively farmed habitats for total waders, Northern Lapwing Vanellus vanellus, Common Snipe Gallinago gallinago and Common Redshank Tringa totanus and second-highest densities for Eurasian Curlew Numenius arquata. Agriculturally unimproved grassland supported the highest densities for many species after wetlands. Agriculturally improved grassland supported consistently low relative breeding densities, and other habitats managed using mechanized farming (lower intensity improved grassland and arable) supported generally low relative densities, apart from for Eurasian Oystercatcher Haematopus ostralegus. Conclusions Describing an entire mixed farming system as nature-rich may mask significant variation in the contribution of different habitats to the maintenance of high nature value. In this system, wetlands that were unmanaged or received low average grazing densities supported disproportionately high breeding wader densities and must be protected to maintain the high densities of most species. The further loss of wetlands, and the move towards intensively managed grassland, is a threat to the maintenance of high breeding wader densities on Orkney and in similar farmed landscapes.