Rabbits 97 



"lows" of the cycle, but some convincing indicators of high density are as follows: 



(a) 157 snowshoes were killed on 20 acres in one season near Higgins Lake, 

 Michigan. 



(b) 200 were killed on 80 acres in one day near Cloquet, Minnesota, with- 

 out any great apparent diminution of the density. 



(c) One rabbit per rail (30 feet) was counted during a trip of unknown 

 length in a railway speeder in Minnesota in the high year 1923 (?), while 20 to 

 50 per mile were counted in auto travel at the same time in the same region. 

 One year later (fall of 1924) scarcely a rabbit could be seen. 



(d) Extreme fluctuation is indicated by the fact that Minnesota planting 

 crews of 10 men each, covering 60 acres per day in close formation, in the low 

 year 1924 saw "3 to 6 rabbits per day with a few more in the swampy places." 

 This was in country where plantations had been seriously damaged the preceding 

 winter. 



It is a safe guess that the "high" populations on concentration areas run as 

 high as five per acre, and that the fluctuation from average is well over 95 per 

 cent or even greater. The densest populations of the last cycle seem to have 

 occurred in Minnesota. It is said that the European hare in southeast Europe 

 seldom runs higher than one per acre, and is not subject to cycles. 



During the high periods in snowshoes it is impossible for new forest planta- 

 tions to survive. Trees up to three feet high are clipped of their tips, branches, 

 and needles. Trees over three feet high are girdled. Natural reproduction of 

 course suffers in the same manner and to the same degree. White pine suffers 

 worst, white spruce next, Norway and jack pine least, probably because the last 

 two species are usually planted on the sandier soils which support less brush 

 and hence furnish less harborage for rabbits. 



It is impracticable to restrict planting operations to low snowshoe years. 

 Forest nurseries must operate on a basis of sustained rather than irregular annual 

 output. Moreover a plantation set out the year when rabbits die would not 

 have grown out of danger by the next succeeding "high" (about seven years). 



Methods of control cannot be efficient until the habits of the snowshoe are 

 known, nor can the degree of control be wisely regulated until its relationships 

 to other game are measured. What, for instance, is the radius of mobility of the 

 individual? This can be determined only by banding. Without this informa- 

 tion the forester cannot tell whether he must destroy the snowshoes for a block, 

 a mile, or five miles around each area to be planted. How can the destruction be 

 effected without undue damage to other species? How long will it last before 

 the area fills up again? What will it cost? What density of population can be 

 tolerated without control? All these questions are shrouded in total darkness. 

 Here again practical conservation is blockaded by lack of biological facts. 



Under the McSweeney-McNary Act, funds have been set up to support one 



biologist at the Lake States Forest Experiment Station, who is to devote a part 



of his time to the study of these questions. The present planting program for 



the Lake States (combined State and Federal) is over $100,000 per year. The 



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