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. Bickne 1, E. P., 
A Study of the Singing of Our Birds, The Auk, I, pp. 60-71, 126-140, 309— 
218, 322-332; II, pp. 144-154, 249-262.—1889. Ruyoaps, s. N., The Mimetic 
Origin and Development of Bird Language, Am. Nat. XXIII, ‘pp. 91-102.— 
1895. SHauer, N. S., Domesticated Animals, 155 pp, 8vo., (Scribner’s).— 
1896. Wircuetyt, C. A., The Evolution of Bird-Song, 10mo., 253 pp., 
(Black, London).—1901. Scorr, W. E. D., Data on Song in Birds, Science, 
N.S8., XIV, p. 522.1904. Maruews, F.S., Field Book of Wild Birds and 
Their Music, 16mo., 262 pp., illus., (Putnam’ 's).—1904. Scorr, W. E. D., 
Inheritance of Song in Passerine Birds, Science, N. S., XIX, p. 154; XX, p. 
282.—1908. Craic, W., The Voices of Pigeons Regarded. as a Means of 
Social Control, Am. Journ. Sociology, XIV, pp. 86-100. 
Tue 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 
