ANALYSIS OF THE STORY OF THE BIRDS. xix 
CuapreR XIII.—Song primarily a call or cry, but now a 
charming factor. It is the latest acquisition, the song bird hay- 
ing a special throat for it. Song still has rivalry in it. Various 
tones for various emotions in many birds. Song as a calling or 
advertising, as a serenading, a cheering, a rejoicing, a warning, a 
threatening, an exasperating, and a subduing factor. 
for Study.—Note the spring songs and incubating songs of 
birds; also their revival at the second nesting period and their 
absence usually in late summer. Note answering crow of cocks, 
gobble of turkeys, coo of doves, whistle of quails, ete. 
CHAPTER XIV.—The mating time of our middle-latitude birds 
extends from January to July. Pairing of resident birds often a 
matter of association. Perhaps many migrants stay from year to 
year paired, and, though separated in migration, return to same 
spot. There is always a charming procedure, however, each year, 
which may be short or long. 
Polygamy largely prevails among the low birds. Males of 
higher birds very devoted to mate in brooding season. Some 
similar instances among low birds, but many males of these de- 
sert their families. Birds of prey long noted as pairing for life. 
Lor Study.—N ote early “ hooting” of owls. Note thistle bird 
or goldfinch in flocks late in June. Watch birds of orchard and 
yard for love antics, especially jays, blackbirds, and flickers. 
Cuaprer XV.—Lost mate is soon replaced by either sex. 
Doubtless many unmated birds extant. Experiments noted. 
The widowed call. Darwin’s note of incompatibility of temper. 
Polygamous tendencies in high birds. Results of environment 
and opportunity on all this. 
for Study.—Among English sparrows if either parent be 
killed the other soon finds a helper. Even if both are destroyed 
others will feed the crying young, or birds of a different species 
will sometimes care for each other’s orphan nestlings. Is the 
acquisition of a new partner as much parental as conjugal ? 
Cuaprer XVI.—Incubation found among a few reptiles only. 
It is probably an acquired habit in birds, the lowest showing 
least of it. Perhaps began in the time necessary to the act of 
depositing eggs subsequent to the first. Earliest birds may have 
covered eggs with sand or hotbed stuff as reptiles and mega- 
podes do yet. Change of place and climate may have necessitated 
