Review of rat invasion biology: implications for island biosecurity

Source: NZ Dept. of Conservation
"In this paper, we review and analyse how three species of invasive rat (Rattus rattus, R. norvegicus and R. exulans) disperse to and invade New Zealand offshore islands. We also discuss the methods used to detect and prevent the arrival of rats on islands. All species of invasive rat can be transported by ship. However, rats can also swim to islands. Swimming ability varies greatly between individual rats, and is probably a learned trait; it is unlikely to be affected by variation in sea temperature in this region. Norway rats (R. norvegicus) are the best swimmers and regularly swim up to 1 km. Therefore, to prevent recurrent swimming invasions of islands, source populations may need to be controlled. Since islands differ in their attributes and individual rats differ in their behaviours, multiple devices need to be used to detect and prevent the invasion of islands, including poisons, traps, passive detection devices and trained dogs."