Manchester Memoirs, Vol. lix. (191 5), No. *t. 5 



been revived after a lapse of about ten months, indeed 

 has survived that period when nuptial activities were 

 latent. Memory and not instinct may explain why a bird 

 returns year after year to an old nesting site, and why, if it 

 departs slightly from the normal, it builds a similar nest 

 each season, although heredity (or instinct if we like) will 

 explain why it first selected a particular environment and 

 constructed its nest on the general lines employed by its 

 species. 



Granting that our bird has an' excellent memory, 

 which urges it to come daily to the wall, and suggested 

 the presence at this spot of its old enemy on February 

 1 2th, when apparently the bird was first influenced by 

 sexual excitement, we are still face to face with the fact 

 that its mental powers have strange limitations. It fails 

 to profit by experience. To its limited reason, if it has 

 any at all, the blow received from the unyielding glass is 

 a hard knock given by its foe. Over and over again it 

 receives this blow at exactly the same spot, yet its mental 

 capacity is so limited that it fails to realise that there is 

 something unreal in this repeated culmination o( its 

 encounters. Does it never wonder why it and its oppo- 

 nent always leave their respective walls at the same 

 moment, always meet at the same half-way spot, and 

 always with the same unpleasant bump? Had the biid 

 never fought with a rival of flesh and blood we might 

 have understood its difficult}', but over and over again it 

 has " scraps " with cock blackbirds who venture near its 

 sphere of influence Surely with so good a memory it 

 must recollect that the blows of beak, wing or foot differ 

 from the everlasting bump against this shadowy rival ; 

 yet, apparently, it has no power to reason why ! 



We can hardly claim that the bird suffers from 

 hallucinations, for it does not imagine a rival and fight 



