Occupancy model for Rattus spp. in high and low human human refuse supplementation conditions

Globally, the genus Rattus is one of the most influential exotic species due to its high rates of competitive exclusion and large dietary breadth. However, the specific foraging strategies of urban and urban-adjacent populations remain largely unknown. We examined Rattus spp. dependency on human food supplementation in a peri-urban population. Through a natural experiment made possible by the COVID-19 shelter in place order in Santa Cruz California, USA, we measured changes in activity between invasive rats and native rodents with and without human supplementation. We measured invasive rat presence in normal (pre-COVID) conditions near dining halls and similar waste sources, and again under COVID lockdown conditions where all sources of human supplementation were removed. We found a decrease in Rattus presence after the removal of human refuse (p < 0.001), while native small mammal presence remained unchanged. These results have strong conservation implications, as they suggest that proper waste management is an effective, targeted, and less-invasive form of population control over conventional forms of poison.