326 BIOLOGICAL LECTURES. 



be the first stage of development. In some of the lower ver- 

 tebrates the attitude remains defensive and is aggressive only 

 in a very low degree, while in others pugnacity is more or 

 less strongly manifested. Among fishes the little Stickleback 

 is especially noted for its fiery pugnacity, which seems to 

 develop suddenly and simultaneously with the appearance of 

 the dark color of the male at the spawning season. 



In pigeons, as in many other birds, this disposition shows 

 itself as soon as a place for a nest is found. While showing 

 a passionate fondness for each other, both male and female 

 become very quarrelsome towards their neighbors. The white- 

 winged pigeon (Melopelia leucoptera) of the West Indies and 

 the southern border of the United States is one of the most 

 interesting pigeons I have observed in this respect. At the 

 approach of an intruder the birds show their displeasure in 

 both tone and behavior. The tail is jerked up and down 

 spitefully, the feathers of the back are raised as a threatening 

 dog " bristles up," the neck is shortened, drawing the head 

 somewhat below the level of the raised feathers, and the whole 

 figure and action are as fierce as the bird can make them. To 

 the fierce look, the erect feathers, the ill-tempered jerks of the 

 tail, is added a decidedly spiteful note of warning. If these 

 manifestations are not sufficient, the birds jump toward the 

 offender, and if that fails to cause retreat, wings are raised and 

 the matter settled by vigorous blows. 



This pugnacious mood is periodical, recurring with each 

 reproductive cycle, and subsiding like a fever when its course 

 is run. The birds behave as if from intelligent motive, but 

 every need is anticipated blindly ; for the young pair, without 

 experience, example, or tradition, behave like the parents. 



It seems to me that this mood or disposition, although in 

 some ways appearing to be independent of the disposition to 

 cover the eggs, can best be understood as having developed in 

 connection with the latter. It has primarily the same mean- 

 ing, protection to the eggs, but the safety of the eggs 

 and young depends upon the safety of the nest, and this 

 accounts for the extension of its period to cover all three 

 stages building, sitting, and rearing. 



