City sicker? a meta-analysis of wildlife health and urbanization

Urban development can alter resource availability, land use, and community composition, in turn influencing wildlife health. Generalizable relationships between wildlife health and urbanization have yet to be quantified, and could vary across health metrics and animal taxonomy. We present a phylogenetic meta-analysis of 516 records spanning 81 wildlife species from 106 studies comparing the toxicant loads, parasitism, body condition, or stress of urban and non-urban wildlife populations in 30 countries. We find a significantly negative relationship between urbanization and wildlife health, driven by higher toxicant loads and greater parasitism by parasites transmitted through close contact. Invertebrates and amphibians were particularly affected, with higher toxicant loads and physiological stress in urban populations as compared to their non-urban counterparts. We also found strong geographic and taxonomic bias in research effort, highlighting future research needs. Our results suggest urban wildlife experience several health risks with potential threats to conservation.