Managing wet grassland landscapes: impacts on predators and wader nest predation

Abstract Since the early twentieth century there has been widespread loss and degradation of wetlands resulting from land drainage and agricultural intensification. Many breeding wader populations in wetlands across Western Europe have declined severely as a consequence of this habitat loss, and their ranges are now increasingly restricted to nature reserves. The habitat requirements of these species, and management actions to achieve these conditions, are well-established but the recovery of many populations may be limited by high levels of predation of eggs and chicks. In this thesis, I assess the distribution of mammalian predators and their small mammal prey in a landscape managed for breeding waders within lowland wet grasslands, and use these findings to consider the potential for habitat management to reduce levels of nest predation for lapwing, Vanellus vanellus, and redshank, Tringa totanus. Within these wet grasslands, I show that small mammals are almost entirely restricted to tall vegetation, which is rare and typically occurs only in verges outside fields. Lapwing nest predation rates are lower when nests are closer to these verges and when there is more verge in the surrounding landscape. Lapwing nest predation is also lower when nests are closer to field edges in drier fields, and further from field edges in wetter fields. Red foxes are the primary nest predator, and nest predation rates of lapwing and redshank, and fox use of tracking plots, are lower when lapwing nest densities are higher. Modelled scenarios of potential influence of future changes in reserve management indicate that changes in surface flooding would have little impact on lapwing nest predation, but removal of verges could result in significant increases of ~10%. Combining environmental factors associated with nest predation with realistic habitat modifications can be a useful tool for assessing the potential scale of consequences of management actions