Improving Urban Habitat Connectivity for Native Birds: Using Least Cost Path Analyses to Design Urban Green Infrastructure Networks

Least-cost path analyses are commonly used in ecology to identify and protect wildlife corridors and stepping-stone habitats that minimise the difficulty and risk for species dispersing across human-modified landscapes. However, they are rarely considered or used in the design of urban green infrastructure networks, particularly those that include building-integrated vegetation, such as green walls and green roofs. This study uses Linkage Mapper, an ArcGIS toolbox, to identify the least-cost paths for four native keystone birds (kererū, tūī, korimako, and hihi) in cen-tral Wellington, Aotearoa New Zealand. The least-cost paths are then used to design a network of green roof corridors that makes the city easier for native birds to traverse. The results identified 27 least-cost paths across the central city connecting existing native forest habitats. Creating 0.7 km2 of green roof corridors along these least-cost paths reduced cost-weighted distances by 8.5-9.3% for the kererū, tūī, and korimako but there was only a 4.3% reduction for the hihi (a small forest bird). In urban areas with little ground-level space for green infrastructure, this study demonstrates how least-cost path analyses can inform the design of building-integrated vegetation networks and quantify their impacts on corridor quality for target species in cities.