168 FRANCIS H. HERRICK 



scratched the surface at a few points only, but suspect that 

 what has been uncovered will prove to be quite characteristic. 



2. THE NEST AND THE PROBLEM OF PROTECTION 



When nest-building is studied in relation to other correlated 

 instincts of the reproductive cycle, as well as to the behavior 

 of the mated pair, many dark places begin to lighten, and many 

 enigmas vanish. 



As we have tried to show in earlier papers " nest-building in 

 birds is to be regarded primarily as one of the serial instincts 

 of the reproductive cycle, the successive terms of which rise 

 and wane in due order when properly and normally attuned 

 in the builders concerned. Not only are the general instincts 

 serial and harmonized, as seen in migration, mating, nest-l^uild- 

 ing, egg-laying, care of the young in the nest, and the like, but 

 some of these arbitrary terms, like the last, are very complex. 

 There is not only an annual cycle, but what may be called a 

 daily " cycle," in a different sense, made up of recurrent acts 

 varying in accordance with the degree of progress attained or 

 the degree of intelligence exercised, whether it be building the 

 nest, brooding, or feeding the young. In building, the acts are 

 serial, and often in a high degree stereotyped, while in w^hat 

 may be also called the feeding " cycle," the round of activities, 

 though more complex, follow in similar chain form. The search, 

 capture, and treatment of prey, return to the nest, testing the 

 throats of the nestlings, and waiting for the swallowing reflex 

 in each, inspecting, and cleaning young and nest, all go on 

 seemingly with clock like regularity, day after day, subject to 

 slight changes as noted above, and to the influence of mate 

 over mate on the one hand, and of parent over child or child 

 over parent, on the other. 



The nest must anticipate the egg, and not the egg the nest, 

 but the order and harmony which commonly prevail are subject 

 to many disturbing influences, leading now to a premature 

 laying of the eggs, to a scamping of the nest or omission of nest 

 building, to the sudden breaking of a first cycle, followed by the 



" See especially Analysis of the Cyclical Instincts of Birds, Science, N. S., vol. 

 XXV, nos. 645-646, 1907; also Instinct and Intelligence in Birds, Popular Science 

 Monthly, vol. 76, pp. 532-536, and vol. 77, pp. 82-97, 122-141, 1910; Life and 

 Behavior of the Cuckoo, The Journal of Experimental Zoology, vol. ix, pp. 169- 

 2.34, pis. 1-7, 1910. 



