CARNIVORA 77 



rats is known to be very great, and it seems to me that the animals 

 met with on the second voyage were the progeny of some which got 

 ashore in ijjo 1 . 



The Rev. R. Taylor says that this animal, the Maori rat, was in 

 general size about one-third that of the Norway rat. The Maoris used 

 to make elaborate preparations to catch them, and hundreds would be 

 caught at one hunting. Taylor says the animal is reported to run only 

 in a straight line, and that the Maoris made special lines of roads in 

 order to lead them into their traps, which were baited with miro and 

 other berries; if these roads were crooked, they said the rats ran into 

 the forest at the bends. They fed entirely on vegetable matter and 

 were greatly prized as food by the natives, who also extracted much 

 oil from them. The native rat quickly disappeared before other rats, 

 and imported cats. It was extremely rare 30 or 40 years ago, and 

 it is probably quite extinct now. As, however, the species is common 

 in Polynesia, occasional immigrants may arrive in New Zealand from 

 time to time. 



Tancred writing of Canterbury in 1856, says: "the native rat 

 forms numerous burrows, rendering the soil unsafe for a horse." He 

 also says "the rat is being exterminated by the formidable invader 

 the Norway rat." 



W. T. L. Travers, writing in 1869, says: 



It has been the fashion to assume that before the arrival of Europeans in 

 this Colony, this creature was common, and to attribute its destruction to 

 the European rat, and, indeed, the natives have been credited with a 

 proverb in relation to this point. It is not in effect impossible that the 



1 In Rats and Mice as Enemies of Mankind by M. A. C. Hinton (British Museum, 

 Economic Series, No. 8), published in 1918, the following statement occurs : " There 

 have been many attempts to calculate the reproductive potential of rats. For instance, 

 F. von Fischer, in 1872, concluded that the progeny of a single pair might in ten 

 years amount to no less than 48,319,698,843,030,334,720 individuals; Riicker, more 

 recently, has computed the increase of a pair in five years at 940,369,969,152 rats. 



Lantz was not so ambitious ; for the purposes of his calculations he assumed the 

 rats to breed only three times a year, and to have average litters of ten. Breeding 

 at this rate uninterruptedly for three years, producing sexes in equal numbers, 

 and with no deaths, the progeny of a single pair at the ninth generation would be 

 20,155,392 rats. 



Zuschlag assumed a pair to have six litters of eight in a year; that the young 

 would breed when three and a half months old, then with equal sexes and no deaths 

 the progeny at the end of the first year would be 880 rats. 



Although such calculations are purely theoretical, and although their results, 

 in ordinary circumstances, will never be approached in Nature, they are not 

 extravagant, qua the power to reproduce, but are based upon moderate and con- 

 servative estimates. In proof we may cite Kolazy's record that two females kept by 

 him had twenty-six litters in a space of thirteen months, and produced 180 young 

 almost double the number assumed by Zuschlag. We can, therefore, readily under- 

 stand how the progeny of a few rats introduced to a new country by a ship may, in 

 favourable circumstances, succeed in overrunning the whole country in the space of a 

 few years." 



