An expert habitat suitability model for the disaggregation of bird survey data: Bird counts in the Netherlands downscaled from atlas block to kilometre cell

Fauna distribution data are often inadequate for the purposes of physical planning at a national scale, because of their lack of detail or incomplete spatial coverage. A method is presented in which an expert habitat suitability model is used for data disaggregation, the opposite of aggregation, and interpolation. Using this method, in this article the data on breeding birds available in the Landscape Ecological Mapping of the Netherlands (LKN) database have been downscaled from atlas blocks to kilometre cells and validated for 14 species with contrasting ecologies. The first step in this procedure is definition of the ecological profile of each species, comprising its habitat requirements and its sensitivity to disturbance. A limited number of conditioning habitat factors are used to describe the ecological profile. The ecological profile is based mainly on expert judgement. The second step involves deriving the habitat characteristics of each kilometre cell that are compatible with the habitat requirements. By comparing the ecological profile with the habitat characteristics of each grid cell, the habitat suitability of every kilometre cells is established. The third step comprises completion and modification of the distribution data. The main change involves an estimation of numbers, based on interpolation, for those atlas blocks for which only the presence of a species has been established. The final step is disaggregation of the counted and interpolated atlas block data over the 25 constituent kilometre cells on the basis of the suitability of each cell. For each step of the disaggregation method, tables and maps of the results are presented. The limitations of the model and of the dataset used are considered and some promising applications of the method discussed.