Shrinking cities are a growing phenomenon. In the United States alone, 13% of cities with ≥100,000 inhabitants have experienced recent population loss. The drivers of urban population decline are complex and can include socioeconomic factors as well as acute events like natural disasters. An emerging literature indicates that human abandonment can result in landscape change and associated ecological shifts. This may in turn serve to augment urban wildlife populations, including potential zoonotic pathogen hosts, such as rodents.
In post-Katrina New Orleans (LA) nearly 80% of the human population was displaced in the immediate aftermath of the 2005 hurricane. Today, human populations have yet to reach pre-Katrina levels in some areas. Abandonment and variable property management have important consequences for urban vegetation in New Orleans, in turn providing a heterogeneous habitat for urban wildlife like rodents. In this study, we determined how rodent communities vary across a gradient of urbanization, abandonment and management strategies. Our goal is to determine the landscape and vegetation characteristics that are related to rodent communities across post-Katrina New Orleans, lending insight into how the trajectory of abandoned urban areas may shape zoonotic pathogen risk.
Results/Conclusions
We trapped rodents on ten residential blocks in each of four neighborhoods within New Orleans and neighboring St. Bernard Parish. Additionally, we trapped rodents in eight locations in a non-developed natural area adjacent to the city. Focal study neighborhoods were selected to represent a gradient of human population density, socioeconomics and vacancy. We detected several non-native pest species: Rattus norvegius, Rattus rattus, and Mus musculus, as well as two native species: Oryzomys palustris and Sigmodon hispidus; with up to four species collected from a single city block.
We found that the diversity of rodent communities differs significantly across our study system, and is highest in neighborhoods where post-Katrina human population returns have been lowest. Results also indicate that vegetation management of urban areas may influence rodent communities, as we found significantly different rodent community composition and abundance in areas where there is ongoing management of vacant lots. We also identified specific vegetation characteristics that relate to members of the rodent community. This work has practical implications for managing the risk of zoonotic rodent-borne pathogens while also adding to a growing body of knowledge regarding the trajectory of abandoned urban landscapes and the (dis) services that are provided.