I found two dead rats around the house today. One was a “normal” size. The other was 22 cm nose to base of tail with another 20 cm of tail, and weighed over 370 g.
Both were poisoned, although I check the gas-powered kill trap every day and have found no rats at all. But then I notice that a whole box of poison blocks in the garage has been emptied, so I presume that there are dens well-stocked for winter with poison. Certainly, the rats are very hungry at present.
The two common species in NZ are rattus rattus (ship rat/roof rat) and norway rat (rattus norvegicus). Ship rats usually have a longer tail compared to body length and bigger ears compared to the norway rat. At a guess these are both Norway rats which can range from 200gm-500gm in size. https://mnwildanimalmanagement.wordpress.com/2011/09/20/mn-mice-and-rodent-removal-cleanup-and-prevention/
My biggest in Corrondella… was lying flat on the table with the tip of its tail still outside the trap entrance. And on the family farm in Canada… I’ve seen them bigger: my biggest catch there was 30cm without tail. It was all rat. We’re fortunate to be dealing with the sizes our cats still think are fun.