Modelling important areas for breeding waders as a tool to target conservation and minimise conflicts with land use change

The impacts of changing land use on our breeding wader populations can be seen in the long-term declines evident in the monitoring data collected by BTO for species such as Curlew, Redshank, Lapwing and Oystercatcher. The intensification of agriculture, land drainage, forest expansion, and increased impacts of predation have all been implicated in these declines. Of these, forest expansion arguably poses the greatest risk to breeding waders.

Since the middle of the 20th century, the rate of forest expansion in Britain has been high, and it is likely to remain a priority for UK governments over the coming decades, contributing as it does towards a drive for net-zero carbon and also to the conservation of woodland birds. Forests, however, can impact negatively on breeding waders by reducing and fragmenting the open habitats in which they breed, and by reducing breeding success due to the activities of woodland-associated predators, such as Red Fox and Carrion Crow. Improvements to our understanding of breeding wader distributions, as well as to the ease with which such information can be accessed by the relevant stakeholders, will help to target wader conservation and minimise negative impacts of forest expansion and other types of development.

Tools that can be used by stakeholders to identify the risks and opportunities for waders require detailed knowledge of their distributions. This can be achieved locally through bespoke surveys, but this approach becomes less practical at larger scales, such as would be required to inform national land use strategies. Where the appropriate datasets exist, large-scale knowledge of species distributions can be achieved by modelling the relationships that exist between the abundance of a species and the various environmental variables that influence this. By using data from Bird Atlas 2007-11 alongside environmental datasets, including those on climate, habitat and topography, BTO researchers were able to model the predicted relative abundances of breeding waders at a 1-km square resolution across the whole of Britain.

The resulting relative abundance values were then compared with several independent datasets, including the BTO/JNCC/RSPB Breeding Bird Survey, to determine whether they were robust. The models worked best for Curlew and Oystercatcher but were less good for species with more restricted distributions and/or habitat requirements, such as Greenshank and Ringed Plover. The abundance values were then placed in one of five strata and used to produce sensitivity maps, primarily to inform high-level policy decisions.

The outputs were also used to investigate broad-scale associations of breeding wader distribution with landscapes and land uses. These reveal that high proportions of populations (relative to their extent) are supported by areas with comparatively low predation risk (e.g. islands and grouse moors) and also by nature reserves. At more local scales, the sensitivity maps can be used to help decide on the levels of scrutiny required to assess development proposals (e.g. establishment of new tree planting schemes). The approach adopted underlines the potential for BTO’s large scale datasets to enable the development of policy tools that can support decision-making at both the national and local scales, leading to the best outcome for birds and people.