The role of landscape-scale factors in shaping urban bird communities

The composition of urban bird communities is clearly affected by local habitat factors. These factors often determine whether individuals choose to occupy urban habitats and how they behave and reproduce once they are there. However, landscape-scale factors also play a major role in the shaping of urban bird communities. Most commonly, these are elements of the landscape for which heterogeneity can be meaningfully measured at scales of 500-2500 m. The influence of landscapescale factors is studied using two approaches-the island biogeography approach and the urbanization gradient approach. Commonly influential factors include the remnant habitat patch size, degree of urbanization, road density, amount of tree or paved area cover and land use (a proxy for human disturbance). While there are no consistent patterns governing the responses of overall species diversity and community composition to landscape-scale factors, when species are grouped by life history guilds, consistent patterns emerge. When considered in conjunction with local habitat factors, research about the effects of landscape-scale factors provides valuable implications for the conservation of avian biodiversity in urban environments, especially when specific species and guilds are the targets of conservation efforts.