AN OCTOBER DIARY. 361 



happily now demonstrated law of evolution. This little 

 mouse has often been noticed as occupying birds' nests 

 built in bushes. I have found them in nests six and 

 ten feet from the ground. To reach them, they must 

 necessarily be expert climbers, and their skill in wind- 

 ing through briers is marvellous. Added to this, they 

 now wander through the dark recesses of hollow trees, 

 often to a consideniijle elevation. What such changes 

 of habit may lead to is readily imagined, and if, as the 

 country becomes more and more settled, these mice find 

 their safety increased in proportion as they remain 

 away from the ground, it is certain that an arboreal 

 mouse may ultimately replace the present species, which 

 now lives upon the surface and only visits hollow trees. 

 That so great a change as I have intitnated should be 

 brought about is quite within the bounds of probability. 



October 25. — There were five minutes of brightness, 

 as the sun rose, and then a rapid overclouding of the 

 whole sky. The prominent effect was to sadly upset 

 the calculations of the birds, and a remarkable restlessness 

 was noticeable. The great flocks of red-winged black- 

 birds, here since yesterday, were broken into little com- 

 panies of a dozen or more, and no two individuals flew 

 in the same direction. The robins were all " at sea," 

 and even the thistle-finches found themselves without a 

 plan. I have seen such distuibed conditions among 

 flocking birds before, but never could I get any clew to 

 the cause. The mere cloudiness of the sky will not ac- 

 count for it. An hour later the sun again shone, and 

 the blackbirds regathered and passed, like a cloud, to the 



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