An novel approach to measuring rat infestations

Risk metrics vs. rat metrics: an alternative approach to measuring and managing urban rat infestations.

Himsworth CG and Byers KA. Journal of Wildlife Management. Accepted 2025-05-21.

Urban Norway and black rats (Rattus norvegicus and Rattus rattus) can have diverse and significant negative impacts on urban landscapes and residents. A variety of different approaches have been developed for measuring rat populations to support management efforts. However, the utility of these approaches has been limited, as they account for the magnitude, but not the consequences of infestations and thus may not reflect the harms that cities are ultimately seeking to mitigate. We propose an alternative approach through the development of a ‘rat risk index’, which would add novel measures of rat-related impacts to existing measures of rat abundance. Such an index would be particularly useful for goal setting, program evaluation, and prioritization in the context of municipal rat management programs.