Managing water levels on wet grasslands for breeding waders : the use of shallow wet features
PublisherUniversity of East Anglia
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Abstract Lowland wet grasslands support a wide range of biodiversity and provide important breeding grounds for many wader species. However, extensive drainage and conversion to arable cropping or intensively managed grassland has greatly reduced the abundance and quality of this habitat across Europe, and caused severe declines in many of the associated waders. Recent agri-environment initiatives provide opportunities to restore wet grasslands, but little is known about the key features necessary to support breeding waders and how these may conflict with commercial farming practises. For breeding waders, the re-introduction of water into the habitat is critically important, and this thesis examines methods of creating and managing within-field wet features and surface water, their impact on the distribution and breeding success of lapwing Vanellus vane/Ius, and the extent to which they are compatible with agricultural operations in the Broads, eastern England. Breeding lapwing are attracted to areas with extensive surface flooding. However, most surface water dries out during the breeding season. The creation of managed shallow wet features allowed water to be retained throughout the breeding season. Fields with higher wet feature densities attracted significantly more nesting lapwing and foraging chicks, and chick condition was significantly improved. Invertebrate biomass and chick foraging rates were higher in wet features than in the surrounding grazing marsh. Neither nest or chick predation rates were related to the proximity of wet features, but predation rates declined with density of lapwing in the vicinity, suggesting an influence of collaborative nest and brood defence. Farmers were keen to enter agri-environment schemes and to use shallow wet features, provided the design was not too complex. Wet feature installation is relatively simple, but maintaining sufficient water levels is critical, especially in the face of increasingly unpredictable water supplies associated with climate change. If managed correctly, shallow wet features offer a tool that may be both effective at improving breeding wader populations and practicable for commercial grazing marsh management.