Tasmania has several species of mammal that we call rat, but the two most common rat are introduced species, the Brown or Norway Rat (Rattus norvegicus) and the Black rat (Rattus rattus).
Both rats are true omnivores, eating anything within range be sure to not put meats into your compost. The rats often inhabit areas close to running water although a frisbee in the yard can supply a rat with enough liquid to survive.
They nest in differing sites but are found in many instances in sheds, under houses and in gardens. They will enter houses without discretion to search for food and will make residence if ample food is available.