228 CONSERVATION OF CANADIAN WILD LIFE 



migration is not a cause of the periodic fluctuation is proved 

 by a study of the total fur returns for the whole territory 

 covered by the Hudson's Bay Company. These figures 

 show that while local migratory movements may occur, the 

 periodic fluctuations are general for the entire territory, 

 and occur with remarkable regularity. 



According to the fur returns of the Hudson's Bay Com- 

 pany the years in which marten was most abundant were: 



1827, 1837, 1846-47, 1856, 1866, 1875, 1886, 1895, 1903. 



The periodic fluctuations occurred in cycles of 



10,"9, 10, 10, 9, 11, 9 and 8 years, 



giving an average periodic cycle of 9.5 years. 



If we compare the years of maximum abundance of the 

 marten with those of the rabbit we find that the years of 

 maximima marten abundance in 1846, 1856, and 1866 oc- 

 curred one year after the maximum rabbit abundance, the 

 years of maximimi abundance in 1875, 1886, 1895, and 

 1903 preceded by two years the years of maximmn rabbit 

 abundance, although they occurred during the period when 

 rabbits in the aggregate were on the increase, and had 

 almost attained the maximum. 



A study of the chart illustrating the fluctuations of mar- 

 ten reveals another interesting feature, namely, the absence 

 from about 1875 onwards of a very marked regularity of the 

 curves of increase and decrease, such as occurred previous to 

 that year. This, I believe, is accounted for by the intro- 

 duction of artificial factors of various kinds which affect 

 the marten population in different parts of the country, 

 and I am inclined to beUeve that the greater destruction of 

 the forests by fire and other causes, which has undoubtedly 

 occurred since 1875, has been mainly responsible for this 

 very noticeable change in the fluctuation of this species of 

 fur-bearer. 



