i 4 Wild Birds 



them, either to desert and begin operations anew, to stay by 

 the nest and save what is left, or, having done this, to fill up 

 the gap by laying more eggs. The course eventually followed 

 depends upon the nature of the bird, or upon the relative 

 strength of fear, the parental instincts, and habit. 



The parental instinct, 1 reenforced by habit, gradually in- 

 creases until the young are reared. It is therefore safest to 

 change the nesting surroundings when this instinct is approach- 

 ing its culmination. 



The general feeling of fear is gradually or quickly suppressed, 

 according to the value of the different factors in the equation, 

 by the parental instinct, which impels a bird at all hazards to 

 go to its young wherever placed. This impulse, though it be 

 weak at first, is strengthened by exercise, or what amounts to 

 the same thing by the growth of habits or associations. 



After a bird once visits the nest in its new position, it returns 

 again and again, and in proportion as its visits to the old nesting 

 place diminish and finally cease, its approaches to the new 

 position become more frequent, until a new habit has been 

 formed, or, if you will, until the old habit is reinstated. 



When the birds approach the nest, any strange objects like 

 the stakes which support the bough, or the tent which is pitched 

 beside it, arouse their sense of fear or suspicion, and they may 

 keep away for a time or advance with caution. If very shy, 

 like most Catbirds, they will sometimes skirmish about the 

 tent for two hours or more before touching the nest. The 

 spell is usually broken, however, in from twenty minutes to 

 an hour, and I have known a Chipping Sparrow and Red-eyed 

 Vireo. to feed their young in three minutes after the tent was 

 in place. 



At every approach to the nest in its new position, the birds 

 see the same objects which work them no ill. The tent stands 



1 This phrase will be used for the sake of brevity and convenience in 

 nearly the same sense as parental attachment or parental love. As we 

 have seen, there is no single parental instinct, but a complex series or 

 chain of instincts belonging to the reproductive period, and subject to 

 marked sexual differences. 



