Effects of heat stress and green cover on urban birds in the megacity of Bengaluru

Abstract Cities, despite being responsible for the loss of habitat as they grow, are also an important refugia for biodiversity. The Global tropical South is undergoing rapid urbanisation, even as they are exposed to heat island and climate warming effects that impact both humans and biodiversity. Eliciting support from policy and decision makers for sustaining habitat for birds in cities may depend on how conservation or restoration of bird habitats is linked to the new emphasis on ecosystem services, including heat stress mitigation. We apriori predicted based on available literature and information that parts of the city with higher levels of heat will have lower bird presences and parts that have higher green cover are likely to support higher presences of birds, but allowing for preference of some birds for open habitats with less greenness. Also, different species and guilds of birds will show diversity in preference for sites in response to heat stress and green cover. We tested hypotheses on the role of green cover and heat stress on bird occurrence using a Bayesian regression approach. We first summarized the information and uncertainty on the direction of the slope of the two covariates as hyper-priors. We used satellite data on heat stress as proxy for urban heat islands and climate warming effects, and green cover (NDVI), to test their effects on habitat quality and spatially explicit occurrence of urban birds. We found that all birds responded negatively to the hotter parts of the city, but the effects of green cover varied with species identity (Pseudo-R2 0.13-0.36). The negative effect of green spaces on some birds could partially be due to the preference of open spaces by species or dependence on anthropogenic food sources for foraging by these species. We mapped heat islands, cooling potential and the bird diversity of green spaces in Bengaluru to identify areas of conservation value that also help mitigate heat stress for citizens. Going forward these results will help us in answering nuanced species level responses and species vulnerability to the impacts of climate change and foster support for conservation of bird habitats in Bengaluru.Dataset descriptionThe dataset is eBird data for the mega city of Bengaluru. We have used heat stress (thermal bands) and green cover to assess the effect of these variables on bird occurrences in the city.