Following a natural disaster, ecological and societal communities recover and change concurrently. Loss of predator species, abandonment, and vegetation regrowth can potentially provide opportunities for populations of human commensal pest species such as Norway rats (Rattus norvegicus) and roof rats (Rattus rattus) to recover quickly and spread. These pest species can pose potential health risks to humans and domestic animals through the transmission of zoonotic pathogens. Though they are globally widespread, little is known about how natural and human-related changes in urban landscapes affect the population dynamics and movement of these species. As part of an interdisciplinary project investigating long-term recovery of human and natural systems in New Orleans, Louisiana after Hurricane Katrina, we developed a “flow network” model to simulate the movement and dynamics of rat populations across an urban habitat. We applied this model to a neighborhood where post-Katrina abandonment still persists to identify how incorporating data on the natural and built characteristics of urban landscapes can affect predictions of rodent population density and movement. We also used the flow network to simulate rodent management actions by treating network nodes (habitat sites), and edges (movement routes) to identify the critical levels of effort required for mitigating spread.
Results/Conclusions
Incorporating landscape data with the flow network model enabled us to identify differences in predicted abundances and movement routes across areas within the neighborhood we explored. Simulating management actions, we found that applying “removal” (e.g. trapping/poisoning) to randomly selected sites required a large fraction of nodes to be treated to see a reduction in the number of sites that became occupied in an invasion scenario. I will discuss how this and other management actions such as resource reduction or impeding movement can be targeted at areas near rodent population reservoirs or movement corridors to more efficiently slow movement and reduce habitat site occupation. Exploring such management strategies using this approach could be important for reducing rodent density or slowing movement to areas where humans may be most vulnerable. I will also describe how we are using extensive local data on ground cover, human demographics, and infrastructure to parameterize movement and life history dynamics in the flow network. Further development of this approach will provide a framework for assessing targeted strategies for mitigating spread of rodent-borne pathogens, and identifying landscape properties affected by disturbances that shape the population distribution of these widespread rat species in urban areas.