Local bird densities and habitats are poor predictors of bird collision with glass bus shelters

Abstract

Bird collisions with glass are a major source of avian mortality, killing billions of birds each year worldwide. Likely, the crucial step to prevent bird-glass collisions is understanding spatial and temporal bird-glass collision patterns. As more and more glass-made constructions appear in public spaces, it becomes essential to identify main drivers of bird collisions with these novel objects. In this study, we perform an attempt to identify local characteristics that may influence the risk of bird collisions with glass bus shelters. We monitored 58 bus shelters from March to July 2018 in urban and rural habitats of south-western Poland. We visited the shelters searching for bird carcasses and traces of collisions but also surveyed birds near shelters, considering the two scales (20 and 100 m of the shelter), and bird behavior (flying vs non-flying). We found 52 evidence of bird collisions and number of collisions per bus shelter ranged from 0 to 7 which substantially deviated from random distribution. Bird abundances recorded near bus shelters, recorded at both 20 m and 100 m scales, were poor predictors of bird-glass collisions and did not improve parsimony of models explaining collision risk. This refers to all recorded birds as well as to the subsets of flying individuals and species being collision victims. Similarly, habitat composition near bus shelters hardly predicted variation in bird-glass collision risk. As we did not manage to identify any important drivers explaining collision risk, we conclude that before we learn how to predict areas with high number of bird-glass collisions, we suggest that developers, urban planners and architects should be advised to design all public transportation shelters using nontransparent materials.