Biology and Impacts of Pacific Island Invasive Species. 11. Rattus rattus, the Black Rat (Rodentia: Muridae)

The black rat, roof rat, or ship rat (Rattus rattus L.) is among the most widespread invasive vertebrates on islands and continents, and it is nearly ubiquitous on Pacific islands from the equatorial tropics to approximately 55 degrees latitude north and south. It survives well in human-dominated environments, natural areas, and islands where humans are not present. Rattus rattus is typically the most common invasive rodent in insular forests. Few vertebrates are more problematic to island biota and human livelihoods than R. rattus; it is well known to damage crops and stored foods, kill native species, and serve as a vector for human diseases. Rattus rattus is an omnivore, yet fruit and seed generally dominate its diet, and prey items from the ground to the canopy are commonly at risk and exploited as a result of the prominent arboreal activity of R. rattus. Here we review the biology of this invasive species and its impacts on humans and the insular plants and animals in the Pacific. We also describe some of the past management practices used to control R. rattus populations on islands they have invaded.