136 



ANIMAL ECOLOGY 



Soper 26 gives a good description of the difference between 

 the time of maximum numbers and of the minimum which 

 follows the epidemic. He says : " It so happened, that upon 

 my first visit to the West in 191 2 the rabbit population was at its 

 height. It was such a revelation after my eastern experiences, so 

 startling, that the vividness of their abundance can never leave 

 me. A certain brushy flat adjoining the White Mud River, 

 south-west of Edmonton, yielded the initial surprise. It was 

 grown to scrub willow, the common trembling aspen, and to 



Fig. 12. — Fluctuations in the numbers of Canadian mammals (taken 

 from Hewitt,^ who used the records of the Hudson's Bay Company). The 

 figures for any particular year represent the effect of increase in the previous 

 year, since the animals are trapped in winter. There is sometimes a lag 

 of more than one year, owing to various trapping factors. 



some extent with rank under- vegetation. The place was 

 infested. I do not hesitate to say that over that tract of per- 

 haps thirty acres hundreds of hares were found. October had 

 come, without snow. The rabbits had already, wholly or in 

 part, donned their snow-white livery of winter, and were 

 consequently very conspicuous against the mellow brown of 

 the autumn woods. At every turn during my ramble they 

 popped up here and there and scurried for fresh cover. Not 

 only in singles, which was astonishing enough, but often twos 

 and even threes started up in wild alarm. '* This was the 



