220 CONSERVATION OF CANADIAN WILD LIFE 



years. Consequently enormous numbers of them have been 

 killed during the last few years, and this no doubt accounts 

 for the greater adoption of the lynx as a fur since 1916. 



The regularity of the periodic increase of the lynx is most 

 strikingly shown in the accompanying chart of the fur re- 

 turns of the Hudson's Bay Company. The first year of 

 abundance, according to these records, occurred in 1831. 

 After that we find the following years of maximum abun- 

 dance: 1839, 1848, 1859, 1868, 1878, 1888, 1897, 1906. 

 Personal records indicate that 1916 was the last year of 

 maximum abundance. The cycles, therefore, occurred in 

 periods of 8, 9, 11, 9, 10, 10, 9, 9, and 10 years, giving an 

 average periodic cycle of 9.5 years. It will be noted, when 

 these years of maximum abundance are compared with those 

 of the rabbit, that the lynx becomes most abundant, or 

 rather the greatest number were caught, during the year of 

 maximum rabbit abundance to three and four years later. 

 This is what one would expect. The capture of large num- 

 bers of lynx during the two or three years after the disap- 

 pearance of the rabbits is accounted for by the ease with 

 which these animals, greatly increased in numbers on ac- 

 count of the period of rabbit abundance, can be captured 

 in snares owing to the absence of their chief article of food. 

 It should be pointed out that a year of greatest abundance, 

 according to the fur returns, would probably follow a year 

 of greater abundance than the fur returns actually show, 

 owing to the fact that when the natural food, rabbits or 

 mice, is most abundant, the animals are harder to trap than 

 when these food animals have suddenly disappeared. The 

 decrease in the number of lynx after a period of abundance 

 is no doubt due to the disappearance of the rabbit. This 

 rule appUes to all predatory animals; their abundance or 

 scarcity is governed directly by the available food supply, 

 whether the animal be a predacious insect or a predacious 

 mammal. 



