Least‐cost path analysis for urban greenways planning: a test with moths and birds across two habitats and two cities

1. One of the major planning tools to respond to urban landscape
fragmentation is the development of ecological corridors, i.e.
interconnected networks of urban green and blue spaces. Least-cost paths
(LCP) appear to be an easy and appropriate resistance-based modeling
method to respond to urban planners’ needs. However, the ecological
validation of urban corridors using LCP is rarely performed and needs to
be generalized to different species, habitats and cities. 2. We developed
an experimental design to test the efficiency of LCP predictions to detect
highly connecting landscape contexts that facilitate individual movements
compared to movements in less connecting landscape contexts. We
deliberately assigned LCP analysis parameters based on the scientific
literature and expert knowledge to test a method potentially easy to use
for urban stakeholders. To extend the validation, we applied our LCP model
to two biological taxa with different habitat requirements:
grassland-dwelling moths and forest-dwelling passerines, and to two
medium-sized cities. 3. We used mark-release-recapture (MRR) methods for
moths and playback recall protocols for passerines to compare the patterns
of individual movement between two contrasted connectivity contexts
determined by the presence and absence of modelled LCPs. MRR protocol
estimated movement rates between herbaceous patches and the two contrasted
connectivity contexts. Playback recall protocol consisted in attracting
individuals from wooded patches to the two contrasted connectivity
contexts. A movement was considered facilitated, when displacement was
rapidly engaged and individuals moved a long distance from their wooded
patch. 4. Moth and passerine movement patterns differed between the two
connectivity contexts: moth recapture rates were higher in highly
connecting contexts than in less connecting contexts. For passerine birds,
responses to playback recalls were faster and movement distance longer in
highly connecting contexts. All results support the hypothesis that both
taxa were more prone to move in corridors modeled by LCP. 5. The
convergence of the results for different biological models and across
cities strengthens the relevance of LCP analysis for planning urban
greenways and provides guidelines for landscape planners in the
development of these corridors to favor the movement and survival of
multiple urban species.