Effect of urbanization intensity on nest-site selection by Eurasian Magpies (Pica pica)

As urban growth continues at an ever-increasing rate, it is important for city architects and city governments to understand the ecological effects of urbanization. As an ideal candidate for studies of urbanization, Eurasian Magpies (Pica pica) have been studied extensively in terms of nest placement in urban environments. However, there have been few quantitative studies on the effect of urbanization on nest-site selection. In this study, we investigated nests of Eurasian Magpies in a city in northern China. The results showed that magpies preferred to nest in tall deciduous broadleaf trees, especially Platanus and Populus spp., in sites with high tree densities, sitting them in a fork of branches, at 15.1 ± 0.3 m (n = 364) above ground level. Magpies in the inner city areas preferred to nest in taller trees within a more wooded area and placed their nests further up the trees, compared with birds in the newer suburbs. We suggest that the selection of nest sites is an adaptation to the increasing intensity of urbanization, having important consequences in terms of avoiding predators and human disturbance. These results provide useful insights into understanding the nature of the relationship between birds and urban habitats, and will be helpful for future landscape and urban planning in north China.