196 Evolution and Adaptation 
courtship have these dancing and vocal performances in nine 
cases out of ten? In such cases, for instance, as that of the 
scissortail tyrant-bird, and its pyrotechnic displays, when a 
number of couples leave their nests containing eggs and 
young to join in a wild aérial dance ; the mad exhibitions of 
ypecahas and ibises and the jacana’s beautiful exhibition of 
grouped wings; the triplet dances of the spur-winged lapwing, 
to perform which two birds already mated are compelled to 
call in a third’ bird to complete the set ; the harmonious duets 
of the oven-birds and the duets and choruses of nearly all 
the wood-hewers, and the wing-slapping aérial displays of the 
whistling widgeons, — will it be seriously contended that the 
female of this species makes choice of the male able to ad- 
minister the most vigorous and artistic slaps?” 
“The believer in the theory would put all these cases 
lightly aside to cite the case of the male cow-bird practising 
antics before the female, and drawing a wide circle of melody 
around her, etc. ... And this was in substance what Dar- 
win did.” ‘How unfair the argument is based on these 
carefully selected cases gathered from all regions of the globe 
and often not properly reported is seen when we turn to the 
book of nature and closely consider the habits and actions 
of all the species inhabiting any ove district.” Hudson con- 
cludes that he is convinced that any one who will note the 
actions of animals for himself will reach the conviction, that 
“conscious sexual selection on the part of the female is not 
the cause of music and dancing performances in birds, nor 
of the brighter colors and ornaments that distinguish the 
male.” 
The differences in color in the sexes of birds are classified 
by Darwin as follows: (1) when the males are ornamented 
exclusively or in a much higher degree than the females; 
(2) when both sexes are highly ornamented ; (3) when the 
female is more brightly colored. A few examples of each 
sort may be chosen for illustration. 
