FLUCTUATIONS OF FUR-BEARING ANIMALS 223 



Red fox: 9, 10, 10, 10, 9, giving an average periodic cycle 



of 9.6 years. 

 Cross fox: 9, 9, 10, 9, 10, giving an average periodic cycle 



of 9.4 years. 

 Black fox: 10, 9, 10, 9, 10, giving an average periodic cycle 



of 9.6 years. 



By comparing these years with the years of maximum 

 abundance of lynx and rabbit, it will be found that they 

 coincide fairly closely. 



The white arctic fox and its colour phase the blue fox 

 inhabit the northern Barren Grounds and the islands of the 

 Arctic Sea in the summer. In the winter many of them 

 wander southward in search of food. This species is re- 

 ported to make caches of food for winter consumption. 

 MacFarlane states that ''Captain Lockwood found several 

 fox lairs. In one hidden rock nook he found fifty dead 

 lemmings, in others (sand and earth covered) there were 

 from twenty to thirty lenmaings, while in a hollow he dis- 

 covered a cache containing part of a polar hare and the 

 wings of a young brent goose and the usual lemming. The 

 lairs appeared to be occupied from year to year." 



The numbers appear to fluctuate very considerably over 

 shorter periods than is the case with the more southerly 

 red fox and its colour phases. The Hudson's Bay Company's 

 returns give the following years of maximum abundance: 



1856, 1861, 1864, 1869, 1873, 1878, 1884, 1888, 1892, 1896, 

 1899, 1903, 1907, 1911. 



The periodic cycles accordingly covered the following num- 

 ber of years: 



5, 3, 5, 4, 5, 6, 4, 4, 4, 3, 4, 4, 4. 



The average periodical cycle occurred in 4.2 years; 4 years 

 was the actual length of the periodic cycle in the majority 

 of the periods. 



