WAYS OF NATURE 
The Baltimore oriole makes free use of strings in 
its nest-building, and the songs of different birds of 
this species vary greatly, while the orchard oriole 
makes no use of strings, so far as I have observed, 
and its song is always and everywhere the same. 
Hence we may say that the lives of some birds run 
much more in ruts than do those of others; they 
show less plasticity of instinct, and are perhaps for 
that reason less near the state of free intelligence. 
Organic life in all its forms is flexible; instinct is 
flexible; the habits of all the animals change more 
or less with changed conditions, but the range of the 
fluctuations in the lives of the wild creatures is very 
limited, and is always determined by surrounding 
circumstances, and not by individual volition, as it 
so often is in the case of man. In a treeless country 
birds that sing on the perch elsewhere will sing on 
the wing. The black bear in the Southern States 
“holes up” for a much shorter period than in Can- 
ada or the Rockies. Why is the spruce grouse so 
stupid compared with most other species? Why is 
the Canada jay so tame and familiar about your 
camp in the northern woods or in the Rockies, and 
the other jays so wary? Such variations, of course, 
have their natural explanation, whatever it may be. 
In New Zealand there is a parrot, the kea, that once 
lived upon honey and fruit, but that now lives upon 
the sheep, tearing its way down to the kidney fat. 
This is a wide departure in instinct, but it is not 
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