A systematic review of Rat Ecology in Urban Sewer Systems

Rats are abundant in the urban ecosystem, posing concerns for public health, infrastructural damage, and negative impacts for other urban wildlife. Sewers are considered to be one of the main reservoirs for urban rat populations, and rats may migrate between sewers and other surface areas in search of food and harbouring sites. Yet the ecology of rats in sewers has received little attention. To address this knowledge gap, this review identifies a number of sewer ecosystem characteristics that have been associated with rat activity. We demonstrate that sewers with narrower pipes, lower flow rates, and construction materials, such as brick and clay, are associated with more rat activity. Further, this review suggests that poorly maintained sewers may contain more crevices and cracks for rats to burrow, leading to greater levels of infestation. Finally, we find that sewers located in residential areas, or closer to food establishment, are more prone to rat presence. Together, these findings uncovered several significant implications for management of rats in sewers, as well as highlight the need for these characteristics to be considered in the urban planning process. Future work is needed to explore how rats in sewers and their management impact above ground populations of rats and other urban wildlife.