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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 nidification, 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. Prematurr Lavine or Eacs, OMISSION OF NE&EST-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 
