Tree cover density attracts rare bird of prey specialist to nest in urban forest

Abstract

Urban forests are important hotspots of biodiversity in the environment of cities and their surroundings but may also stand out from neighbouring forests by greater tree species diversity, higher tree age and greater share of deciduous species. However, they are usually not connected with nesting of rare birds of prey, especially dietary specialists. Unexpectedly, I have found Honey Buzzard Pernis apivorus nesting in such a forest in a 300,000-inhabitant city in North-Eastern Poland. The male of this pair was caught and fitted with a global positioning system logger. Using a tree cover density raster, I show that both for nesting and foraging, Honey Buzzards preferred dense canopies. Even with anthropogenic disturbance, the urban forest still offered the best conditions (greatest tree cover) for this specialist species in a 10 km radius. This finding shows that the advantages of some features of urban forests (deciduous character, dense canopy) can overcome disadvantages of the urban environment even for rare, large raptors. Also tree cover density seems a promising indicator of biodiversity in urban forests and should be tested in larger studies.