The habitat associations of dunlin (Calidris alpina) in the Flow Country of northern Scotland and an improved model for predicting habitat quality

A previous study in the Flow Country of northern Scotland has shown that variation in the abundance of dunlin (Calidris alpina schinzii Brehm) can be predicted from the near-infrared reflectance of moorland derived from satellite imagery. Low reflectance corresponds to high densities of dunlin and vice versa. Here we report further evidence for this relationship. Dunlin are closely associated with wet areas of moorland containing pool-systems and water strongly absorbs near-infrared radiation. Consequently, it was hypothesized that moorland with many pool-systems would tend to have low near-infrared reflectance and large numbers of dunlin. Results presented here suggest that this hypothesis is incorrect. Variations in pool-system area do not greatly influence near-infrared reflectance. Dunlin abundance is a function of both pool-system area and the characteristics of the matrix between water bodies. Although matrix variation is important in determining dunlin density, dunlin nevertheless show strong avoidance of the matrix at fine spatial scales by clustering in and around pool-systems. This avoidance is similar in strength regardless of matrix type. Pool-systems are occupied preferentially wherever they are present, but the density of birds on pool-systems varies depending on the nature of the surrounding matrix.