84 THE PLUMAGE OF BIRDS 
Is it performed by one or both sexes? Is there any regularity in the daily 
periods of sitting? Does one sex ever feed the other while on the nest? 
Will the sitting bird permit a near approach? Does the bird return to the 
nest directly or with much caution? Are the eggs turned in the nest? Are 
they covered when left? How is the egg-shell disposed of after hatching? 
The Young Bird.—What is the condition of the young bird at birth? 
If blind, when do the eyes open? What notes does it utter? How long is 
it in the nest? How is it fed? on what? how often? Is the food prepared? 
What prevents the young bird from being over-fed? At what rate does it 
increase in weight? How is it brooded? How is the nest cleaned? Do the 
young obey the parent? When is fear first shown? Is it instinctive? What 
nest exercises are manifested? How long after leaving the nest is the young 
bird dependent on the parents? What induces it to leave the nest? Does 
it fly at once? Does it return to the nest? Does it frequent roosts? Does it 
flock with other young or with adults or both? How do the parents protect 
the young? 
REFERENCES 
‘ es largely to the more recent studies of the nesting habits of 
irds. 
1844, Renniz, J., Bird Architecture (London).—1878. ALLEN, J. A., 
An Inadequate Theory of Birds’ Nests, Bull. Nutt. Orn. Club, III, pp. 22— 
32.—1900. CuHapman, F. M., Bird Studies with a Camera, 12mo., 218 pp. 
ills., (Appleton).— 1900. Dugmors, A. R., Bird Homes, 4to., 183 pp., 
ills., (Doubleday).— 1902. Jos, H. K., Among the Water-Fowl, 12mo., 224 
pp., ills, (Doubleday).— 1905. Jos, H. K., Wild Wings, 8vo., 341 pp., 
ills, (Houghton, Mifflin).— 1905. Herricx, F. H., Home Life of Wild 
Birds, rev. ed., 255 pp., ills., (Putnam’s). (Important.) — 1907. FINLEy, 
W.L., American Birds, 12mo., 256 pp., ills., (Scribner’s).—1907. CHAPMAN, 
F. M., Camps and Cruises of an Ornithologist, 8vo., 432 pp., illus., (Apple- 
ton).—1908. Watson. J. B., The Behavior of the Noddy and Sooty Terns, 
Papers from Tortugas Lab. of Carn. Inst., II, pp. 189-255, (Important). 
—1910. Herrick, F. H., Instinct and Intelligence in Birds, Pop. Sci. 
Monthly, June, July, and August.— 1911. Herrick, F. H., Nests and 
Nest-building in Birds, Journ. of Animal Behavior, Vol I, (Holt). 
THe PLUMAGE oF BirpDs 
The Molt 
Plumage Wear 
The Colors of Plumage 
Color and Age 
Color and Season 
Color and Sex 
Color and Climate 
Color and Concealment 
Banner Marks 
Albinism and Dichromatism 
Feathers are the only character which birds do not share with 
other forms of life. No other animals are feathered and no birds are 
featherless. 
It is apart from our object to describe here the development and 
structure of feathers, but rather to discuss their function, as in their 
