1890. | Probable Causes of Polygamy Among Birds. 1033 
birds more conspicuous and liable to destruction. From 
our general knowledge of female preferences we must be- 
lieve these highly-plumaged males more desirable than the 
plainly-colored two-year-olds; but the percentage of the former 
to the latter is so very low that it is highly probable many fe- 
males in their extremity “ took hold of one” (figuratively speak- 
ing), preferring dishonor to the reproach of pairing with a less 
handsome bird. In view of the maximum development of the 
Paradiseide in their secondary sexual characters, an opposite 
course of selection on the part of the female would result in the 
regression of development to former obscurely-tinted male types, 
provided the unadorned males of the second year transmit to their 
offspring less distinctive secondary sexual characters than males 
of the third year. Such variability in the degree of transmission, 
when limited by age, is worth special study. 
The conspicuous adornment of male polygamous birds, as I 
have said, exposes them to the scrutiny of their enemies, whereas 
the females, retaining their original protective colors, are still 
preserved. Another cause of male destruction is due to their 
greater value as prey, being larger and better favored than the 
opposite sex. These facts, coupled with their great destruction 
of each other, overbalance everything conducive to an increase of 
male birds and favor the preponderance of females, so that 
although a larger percentage of males be yearly produced, the 
law of survival, exclusively directed against them, perpetuates the 
inequality. Such, we exclaim, are the sad results of what may 
be termed psycho-physical development! Let not mankind sit in 
judgment here. The skirts of immortals are yet defiled by simi- 
lar practices. 
Before quitting this interesting subject we may discuss a few 
questions arising from the nature of our deductions. 
Firstly,—among our native birds it is asserted that, after the 
turkey (Melagris gallopavo), the cock of the plains (Centrocercus 
urophasianus) and the pinnate grouse (Cupidonia cupido) practice 
polygamy to the greatest extent. It will be objected that the two 
6 See Wallace in Annals and Mag. Nat. Hist., Vol. XX., on age of attainment of full 
male plumage in Paridisea apoda. 
