In compiling this dissertation I have two broad aims in mind. Firstly, to present the necessary information for the detection and identification of the rats found in New Zealand. Much of this information is already existing, however its scattered nature presents delays in its accumulation and therefore its effectiveness. In the selection of appropriate material, I hope to facilitate the ease of rodent detection and identification. This should lead to more efficient monitoring for rodents in reserves by the local staff. Secondly, to present all details and results of the Tawhitinui Island campaign, an experiment aimed at testing a practical eradication method against ship rats (Rattus rattus).