10 ANIMAL COMPETITORS 



ington the average litter is 10. A pair and 

 their progeny breeding three times a year 

 would, thus, if all remained alive, produce a 

 population of more than 20,000,000. "Of 

 course, such results never occur in nature. 

 Apparently not nearly half the rats born are 

 females ; at least, among mature rats the males 

 greatly predominate. Then, too, the life of 

 young rats, as well as that of the old, is a con- 

 tinuous struggle for existence. Disease, the 

 elements, natural enemies, the devices and cun- 

 ning of man, and even cannibalism are contin- 

 ually at work to reduce their numbers. ' ' 



The young are born, after a gestation period 

 of 21 days, in a burrow dug in the ground under 

 buildings, piles of lumber or wood, beneath 

 strawstacks, etc., or simply bored into a stream- 

 bank. They are naked and blind at birth, but 

 develop with great rapidity. 



What it costs to board our rats. The dam- 

 age done by rats over so great an area as 

 the United States or Canada, is incalculable. 

 David E. Lantz, in the document from which 

 I am quoting freely, summarizes their destruc- 

 tion thus : 



