CARNIVORA 83 



by acclimatisation societies and private individuals in their attempts 

 to establish game and other birds. But it is impossible to say which 

 species is responsible, or whether both are equally so. It is clear in 

 the preceding references that it has not always been possible to be 

 sure which species of rat was referred to. I have therefore thought 

 it advisable to add in a note some general facts on rats culled from 

 recent sources. 



NOTE. In 1869-70 there occurred a great visitation of rats (apparently 

 Epimys norvegicus) in the north and north-western plain country of Queens- 

 land. The numbers were said to be incredible, and one writer stated that 

 "one rat to every ten square yards in each mile would not represent any- 

 thing like the numbers." H. E. Longman says that "in Australia, judging 

 from available statistics, the black rat is quite as common as the brown, 

 and is, of course, the species most frequently found in buildings, whereas 

 E. norvegicus is characteristically a ground rat." In Mr Hinton's pamphlet 

 already referred to he says, in regard to general habits of rats: "Rattus 

 rattus is essentially an arboreal or climbing animal, and it rarely burrows; 

 hence, where infesting buildings or huts, it is found usually in the walls, 

 ceilings, or roof, not in cellars or drains. Although cautious, it does not 

 shun mankind, and it enters into far closer relations with its unwilling 

 host than does the Brown Rat. For this reason it is often the species 

 principally concerned in the transmission of plague. It drinks little, and 

 seldom, if at all, enters water voluntarily. As already mentioned, this is 

 the common rat on ships. In most cases it reaches or leaves the ships by 

 climbing their cables while they are in dock; sometimes it is introduced 

 with grain and other merchandise. Its diet is of a most varied description, 

 but, probably in consequence of its more salubrious station, it is a cleaner 

 feeder than R. norvegicus. 



R. norvegicus is essentially a water loving and burrowing animal; 

 although far less agile than R. rattus, it is a good climber. As compared 

 with the last named species, it is far more voracious and cunning; its 

 greater size and strength, and its much greater fecundity, render it, as far 

 as material prosperity is concerned, a much more formidable enemy of 

 mankind. On the other hand, although it spreads many serious or fatal 

 diseases, it usually exhibits a certain shyness of man, so that, in normal 

 conditions, it is probably slightly less important than R. rattus as a carrier 

 of plague." 



Prof. P. Chavigny in articles in the Revue Gentrale des Sciences of July 

 15-30, 1918, on "The Invasion of Trenches by Rats" (condensed in 

 Nature, of igth September, 1918), gives certain interesting facts regarding 

 these animals, viz. both brown and black rats: 



(a) Starvation kills a rat in about 48 hours. 



(b) The period of gestation is 21 days, and the minimum time between 

 two litters is 62 days. The female rat may have five litters in a year, and a 

 litter consists of about ten young. A female is capable of producing a 

 litter at the age of 2| to 3 months. A simple calculation shows that a pair 



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