Laboratory rats as trap lures for invasive Norway rats: field trial and recommendations

The Norway rat (Rattus norvegicus) is a highly destructive invasive species but while rat eradications on islands are effective, detection of survivors or reinvasions is challenging. We tested whether laboratory rats can act as lures for wild rats. We live-trapped rats first by using food baits, followed by live trapping using male and female lure rats vs controls (i.e. the same trapping device but without the lure animal). Norway rats were more frequently attracted to lure rats compared with controls. There was no sex bias in the trapped animals. Numbers of Norway rats caught with food baits compared with lure rats did not differ, but trapping rates were higher when using lure rats. Rat activity was detected only around lure rats. Ship rats (Rattus rattus) were not caught with Norway lure rats. We demonstrate the potential for detecting invasive Norway rats using conspecific rats as lures. Further research looking at conspecific attraction in other situations and in direct comparison with food-baited traps is needed to determine the efficacy of this method as a control measure.