582 



Life-histories of Northern Animals 



above by some enemy, or from below by the Gopher itself. 

 The dotted spaces represent very old hills, either of last spring 

 or of the year before. Those faintly outlined are recent hills, 

 and the heavy-l'ined hills were about a day old. A sample hill 







o ..',.• 



\\"0 :• -' v-3 ^^ — ^- •• -.. i^. -^ i' • . 





(\Uforni» ^X,-f((t If hills on f7i<j.y»rc(i. 



Fig. 170 — Work of inonticola, near Lake Tahoe, California, Sept 23. 1899. 



SIZE OF 

 MOUNDS 



is seen in the middle of the right or south side. It was i8 

 inches wide, 4 inches high, and contained about a third of a 

 bushel of earth. This is probably an average hill, but in 

 Manitoba I have seen others 10 inches high and 4 to 5 feet 

 across, thrown up from a single burrow, and containing 7 or 8 

 bushels of loam. 



On April 29, 1904, at Whitewater, Manitoba, E. W. 

 Darbey and I staked off 20 yards square in the middle of a 

 large Gopher tract, then carefully counted the hills — there 

 were 78. We then measured in a bushel measure a number 

 of the mounds, and found that an average one was a good half 

 bushel, a large one 2 bushels. Altogether they represented 

 about 40 bushels of earth. All these had been made ap- 

 parently this season. 



In the Sierra, September 23, 1899, I saw 10 large hills 

 thrown up in one day from one tunnel; many extensive areas 

 had had the surface wholly turned that year. I noted some, 

 of course, with little gopher-work, but very few with none. 



