92 THE POPULAR SCIENCE MONTHLY 



bank, which was later successfully drilled and occupied by the same pair. 

 The subject of compound nests is too long and involved for full 

 discussion here, but from the builder's standpoint, which is that of 

 instinct, I think there is ground for regarding such a composite struc- 

 ture as that reared on the cooperative plan by the ani or Savanna 

 blackbird, as in reality a multiple nest. 



IV. Eccentric Behavior; Robin offering String to Young 



Under this head we shall describe a special case of what we have 

 frequently referred to as the " overlap " or struggle of competing 

 instincts. The incident happened in a neighbor's yard on One Hun- 

 dred and Second Street, Cleveland. A pair of robins had nested in this 

 yard, and successfully reared young, which were then hopping about in 

 the speckled-breasted stage, and begging for food. On a certain occa- 

 sion one of the parents was seen offering a long piece of twine to one 

 of the youngsters, and trying to cram it into its throat. This robin 

 would repeatedly gather up the string, as it would the coils of an 

 angleworm, and offer it in the usual way, but string not being to the 

 taste of this fledgling, it was as often rejected. After a time the old 

 robin flew with the string into a tree. 



With these facts in view, how shall we interpret such extraordinary 

 behavior? We consider this case of the robin a most unusual and 

 interesting exhibition of the conflict of opposing instincts, for according 

 to this idea, the bird was at the close of an old reproductive cycle, and 

 the beginning of a new one. She had fallen, as it were, between two 

 stools. Impelled by the rising instinct of nidiflcation, she gathered 

 the string, when aroused by the calls and sight of her young she was 

 induced to offer it; again under the sway of the building instinct, she 

 flew with the string to a tree. We can judge of the sequel, although 

 unfortunately observation on the robin's conduct stopped at this point. 

 The popular interpretation that the bird was crazy gives place to some- 

 thing which we can measurably understand, or coordinate with other 

 related facts. On the other hand, what a commentary such an act 

 furnishes upon the effective intelligence of birds, when under the sway 

 of powerful instincts. Does not the robin know a " hawk from a 

 handsaw," or a worm from a piece of string? The behavior of the 

 great herring gull with chicks still requiring her care, in going through 

 all the motions of nest-building, and returning to her young again, 

 would seem to be similar in all essential respects. 



V. Premature Laying of Eggs, Omission of Nest-building 



and Parasitism 



Lack of attunement between the appearance of the nest and eggs, 

 or terms 3 and 4 of the cycle is very common. Too frequently the egg 



