THE SUMMIT OF THE YEARS 



disclose to you in rigidly controlled experiments? 

 If the free bird is endowed with any sense-powers 

 of which the "mere observer" can gain no first- 

 hand knowledge, what chance has the laboratory 

 observer of gaining a first-hand knowledge of 

 them? 



The field observer sees the woodpecker excavating 

 a cavity in a dry limb or stub in the autumn; he sees 

 that all birds of this species proceed in exactly the 

 same way, because they all have the same organiza- 

 tion, and hence the same needs; he sees how care- 

 fully the bird usually places its entrance where it 

 will be more or less shielded from driving storms; 

 he sees that it rarely or never selects a limb that 

 is too rotten, or insecure; he sees where it makes 

 many beginnings and then abandons the limb be- 

 cause, apparently, it is too soft or too hard; he 

 sees the bird cautiously resorting to these retreats 

 as night comes on; he sees him living alone in 

 there, little hermit that he is; he sees how he is often 

 dispossessed of his cabin by the hairy woodpecker, 

 or by the flying squirrel, or the English sparrow; 

 he sees him selecting a dry resonant limb for a 

 drum in the spring, on which to drum up a mate; 

 he sees his changed demeanor when the female 

 appears, the curious, mincing flight, as if on the tip- 

 toe of his wings, with which he follows her about — 

 he sees, in short, a long series of interesting facts 

 which reveal the real psychology of the bird, and 

 190 



