Effects of air pollution on heron habitat suitability in Tianjin City: an ensemble modelling approach

Abstract This study presents the first systematic integration of air pollution variables—PM 2.5 , NO 2 , SO 2 , and O 3 —with conventional environmental predictors (climate, topography, and land use) to assess heron habitat suitability in Tianjin, China. An ensemble modelling framework based on the biomod2 package was applied to five heron species: Pond Heron ( Ardeola bacchus ), Little Egret ( Egretta garzetta ), Great Egret ( Ardea alba ), Night Heron ( Nycticorax nycticorax ), and Middle Egret ( Ardea intermedia ). Incorporating air pollution data significantly improved model prediction accuracy, with area under the curve values increasing by up to 4% and true skill statistic values by up to 11%. Ozone (O 3 ) and sulphur dioxide (SO 2 ) were identified as the dominant constraints on Pond Heron habitat suitability, whereas NO 2 emerged as the primary air pollution predictor for Night Heron, with O 3 and SO 2 also contributing to habitat suitability. Response curve analysis revealed non-linear, species-specific threshold relationships between pollutant concentrations and habitat suitability. These findings establish air pollution as a critical, previously underrepresented determinant of avian habitat quality in urbanizing environments, and provide a scientific basis for integrated conservation strategies coupling pollution control with ecological restoration.