Assessing Urban Bat Roosting Ecology in Shanghai Metro Corridors

Thesis Abstract

Urban bat populations are increasingly exposed to anthropogenic landscapes, yet the roosting ecology of bats within dense metropolitan infrastructures remains underexplored, limiting effective conservation and urban planning. This study addresses the gap by examining how Shanghai’s elevated metro corridors function as roosting habitats for insectivorous bats, assessing species occupancy, roost selection, and temporal activity in relation to corridor morphology, light pollution, noise, and hydrological features. The aims are to (i) quantify roost occupancy and species richness across representative metro segments, (ii) identify habitat attributes driving roost selection, and (iii) evaluate temporal patterns of roost use in relation to seasonal climatic variation and metro operations. Specific objectives include (a) inventorying bat species using metro corridors during over two field seasons, (b) modeling occupancy probability and roost fidelity as a function of roost microhabitat characteristics, structural features, and proximity to foraging habitats, (c) analyzing diel and seasonal activity using acoustic and thermal imaging data, and (d) assessing potential conflict zones and mitigation strategies for urban cohabitation. The study draws on a multi-method approach under a Brockington-inspired, socio-ecological framework and tests predictions derived from the habitat suitability and edge-effect theories, incorporating a conceptual model that links urban structure, light–noise gradients, and roost microclimates to occupancy dynamics. The research adopts a sequential mixed-methods design, with a preliminary quantitative survey followed by qualitative expert consultations to contextualize findings within urban biodiversity governance. A stratified random sampling of 24 metro corridor sites across four districts was implemented, with a target roost search effort of 480 roost-days and acoustic sampling totaling 1,200 hours over two active bat seasons. Data collection integrated four instruments (i) ultrasonic bat detectors (Pettersson D500x) for species-rich call data and activity indices, (ii) infrared thermography cameras for roost emergence/return timing, (iii) microclimate recorders (HOBO Pro v2) capturing temperature, humidity, and wind at canopy and crevice levels, and (iv) structured habitat assessment sheets to document roost substrates, crevice dimensions, shade cover, proximity to water bodies, and illumination intensity. Population parameters will be estimated via occupancy modeling (MacKenzie et al.) with Bayesian inference to accommodate imperfect detection, while activity levels will be analyzed using generalized linear mixed models (GLMMs) with site and season as random effects. Roost preference will be further explored through conditional logistic regression comparing occupied versus non-occupied roost microhabitats. Temporal patterns will be examined through time-series analyses and Fourier transforms to identify periodicities linked to metro operation schedules and nocturnal foraging windows. Thematic analysis of interviews with urban ecologists, transit authorities, and bat workers will elucidate governance and mitigation considerations. Expected findings anticipate detection of 5–7 bat species, with Nyctalus noctula and Pipistrellus-like species showing higher occupancy in corridor segments with dense vertical structure and lower artificial lighting. Roost selection is hypothesized to correlate positively with crevice availability, stable microclimate, and proximity to green corridors, while anthropogenic noise and light gradients are predicted to constrain occupancy at exposed elevations. Seasonal variation is expected to influence emergence times and activity peaks, aligning with local climate data and metro throughput. The study will contribute to knowledge by detailing urban roost dynamics within a high-density megacity, offering transferable insights into how transit corridors function as biodiversity corridors and roost habitats, and informing urban design that mitigates bat–human conflict. The practical implications include evidence-based recommendations for corridor architecture and lighting guidelines, strategic placement of bat-friendly roosts, and integration of bat monitoring into urban planning processes. The main conclusion is that Shanghai metro corridors can support stable bat roosting ecology when roost microhabitats are preserved and lighting regimes are managed, enabling coexistence without compromising transit efficiency. Recommendations emphasize adaptive lighting strategies, retrofitting opportunities for roosting substrates, and routine monitoring protocols to sustain urban bat populations amid ongoing metropolitan development.