November 2008. A novel design for a rat/mouse catcher suggested by New Zealand.
Take a 5 or 10 litre bucket. Push a piece of strong metal wire (No 8 fencing wire), slightly longer than the width of the top of the bucket, through the base of a round plastic bottle (about 4 cm diam.) and out the cap to make a roller. Make certain that the bottle turns freely on the wire. Place this wire and roller across the top of the bucket (make a hole each side if necessary). Place a piece of wood from the ground up to the top edge of the bucket to act as a ramp for the rodent. (Hook a nail into the wooden ramp onto the side of the bucket so that it does not slip off). Place a very small quantity of peanut butter at the top of the ramp and around the middle of the plastic bottle. Do not put too much. Place water in the bucket up to a depth that the rodent cannot stand up on the bottom of the bucket. The rodents smell the peanut butter, run up the ramp, try to jump onto the plastic bottle to get more peanut butter and slip off into the water. They either drown or in the morning they can be disposed of.
The trap was suggested for a problem with rats in the storage shed and nursery at Aiyura Highlands Research Station, Papua New Guinea.
A very good reference for identification of the different species is on-line. See Aplin KP, Brown PB, Jacob J, Krebs CJ, Singleton GR (2003) Field Methods for Rodent Studies in Asia and the Indo-Pacific. ACIAR Monograph No. 100. 223pp. Australian Centre for International Agricultural Research, Canberra.
The entire volume is online: http://www.irri.org/irrc/Rodents/publications.asp#Field_Methods_for_Rodent_Studies_in_Asia_and_the_Indo-Pacific.
Chapter 11 has data on R. exulans, R. rattus plus the other possibles (in the PNG case) R. praetor and R. mordax at: http://www.irri.org/irrc/Rodents/publications/field%20methods-Part%203.pdf