6175 I cannot tell if the rat on the top of the pictures is a Norway rat or a black rat. It is much larger than the rest of what appear to be black rats. These rats were trapped on Tinian Island, Commonwealth of the Northern Mariana Islands. They were trapped with Victor rat traps, baited with peanut butter and oats. Any help greatly appreciated. Best regards, Brian, Research Associate, Center for Environmental Management of Military Lands, Colorado State University.
Only three species of rat, all introduced, have been reported from Tinian. The commonest species is the roof rat, Rattus rattus, likely was brought in by Europeans. The Polynesian rat, R. exulans, likely accompanied early Polynesian settlers, and does not appear to have been reported from Tinian since 1945. The Norway rat, R. norvegicus, was reported in 1913, but that identification now appears doubtful. For details, see “The mammals of Tinian, Mariana Islands” (https://tinyurl.com/ycqudhy4). The appearance of hair on the tail of the larger rat likely is an artifact of the tail having been crushed to some extent. I believe that it most likely is an adult male roof rat. Ed Saugstad, retired entomologist; Sinks Grove, WV.