What does urbanization actually mean? A review and framework for urban metrics in wildlife research

1. Extensive research has demonstrated that urbanization strongly alters ecological processes, often perniciously. However, quantifying the magnitude of urban effects and determining how generalized they can be across systems depends on the ways in which urbanization is measured and modelled. 2. We coupled a formal literature survey with a novel conceptual framework to document and synthesize the myriad of metrics used to quantify urbanization. The framework enables clear cataloguing of urban metrics by identifying) the urban component measured, ii) the method of measurement, iii) the metric’s spatial scale, and iv) the metric’s temporal nature. Thus, the framework comprehensively captures the what, how, where, and when of urban metrics.3. We documented striking variability in urban metrics with respect to which urban components were measured as well as how, where, and when they were quantified. Overall, our survey revealed that they tended to be: i) be structurally-focused, ii) methodo...