66 THE NESTING SEASON 



the nesting-season? Among single-brooded species? Among double-brooded 

 species? Mention types of mechanical and other forms of bird music. 

 What is the function of song? What are the earliest and latest dates on 

 which certain species have been heard singing? What species arrive in 

 song? What is the relation between song and the color of a bird's plumage? 

 What birds sing sotto voce? Note the hours at which certain birds sing. 

 What relation exists between the song-perch, haunt and habit (terrestrial 

 or arboreal)? What birds sing at night? What birds sing on the wing or 

 have a true flight-song? Give instances of individual variation in song; 

 of variation with age; of geographical variation. Do young birds sing 

 their first fall? Do birds inherit the call-notes and songs? When does the 

 young bird acquire its song? Give instances of mimicry in birds. 



REFERENCES 



1871. DARWIN, C., The Descent of Man. 1884-5. BICKNELL, E. P., 

 A Study of the Singing of Our Birds, The Auk, I, pp. 60-71, 126-140, 209- 

 218, 322-332; II, pp. 144-154, 249-262. 1889. RHOADS, S. N., The Mimetic 

 Origin and Development of Bird Language, Am. Nat. XXIII, pp. 91-102. 



1895. SHALER, N. S., Domesticated Animals, 155 pp, 8vo., (Scribner's). 



1896. WITCHELL, C. A., The Evolution of Bird-Song, lOmo., 253 pp., 

 (Black, London). 1901. SCOTT, W. E. D., Data on Song in Birds, Science, 

 N. S., XIV, p. 522. 1904. MATHEWS, F. S., Field Book of Wild Birds and 

 Their Music, 16mo., 262 pp., illus., (Putnam's). 1904. SCOTT, W. E. D., 

 Inheritance of Song in Passerine Birds, Science, N. S., XIX, D. 154; XX, p. 

 282. 1908. CRAIG, W., The Voices of Pigeons Regarded as a Means of 

 Social Control, Am. Journ. Sociology, XIV, pp. 86-100. 



THE NESTING SEASON . 



Date The Egg, continued 



Number of Broods Colors 



Courtship Shape 



The Nest Variations 



Enemies of Nesting Birds Incubation 

 Nesting-site The Young Bird 



Material Condition at Birth 



Construction Food 



Character of the Nest Nest Sanitation 



Inheritance Defence of the Young 



Parasitism Voice 



The Egg Nest Exercises 



Number Laid Fear 



Size Flight 



Date. Why should a bird build its nest at a certain time of the 

 year? Some variation in nesting dates, it is true, is shown by all birds, 

 but this does not affect the truth of the statement that most species 

 have a definite nesting season. 



In a general way it may be answered that the nesting period, as a 

 whole, is determined by those climatic changes, which, independent 

 of latitude, divide the year into seasons. In the extreme north, where it 

 is possible for birds to nest only during a small portion of the year, the 



