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 applies 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. 
