'TWIXT COLD AND HEAT. 78 



is at its height, makes it a busy and instructive time for 

 the practical naturalist. 



Birds when nesting, more than at any other time, 

 sliow what they really are, intellectually. If one is 

 lazy, stupid, or disabled in any manner, the fact will then 

 become patent, and leads, at times, to divorce among 

 mated birds. Among catbirds, wrens, and orioles I have 

 known quarrels to occur, arising from such causes as I 

 have mentioned, and which led to permanent separation, 

 abandonment of half-constructed nests, and even a full 

 complement of eggs. 



Having met, in the summer of '84, with many in- 

 stances wherein birds have shown considerable ingenuity 

 in overcoming tlie ill-results of accidents to their nests, 

 such as often arise during violent storms, I determined 

 to test their intellectual powers generally, by a series of 

 simple experiments, hoping thereby to be able to deter- 

 mine to what extent birds exercise their reasoning facul- 

 ties. 



My experiments, and the inferences I drew, are as fol- 

 lows : Noting the material being gathered for the partly 

 constructed nest of a chipping-sparrow, I placed a small 

 quantity of the same in a conspicuous position near by. 

 It was seen by the sparrows, and examined, but none 

 was removed. I placed a portion of it upon the margin 

 of the unfinished nest : it was promptly removed by the 

 male bird, who used only such materials as were brought 

 to him by his mate. The following day the task of 

 lining the nest with hair was commenced. I placed a 

 quantity of this material on a branch near by, but it 

 was passed unnoticed. I next placed a few hairs on the 



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