i 9 2 BIRDS OF LA PLATA 



constructed than is usual with the Tyrants* Soft 

 materials are preferred, and in many cases the nests 

 are composed almost exclusively of wool. The inside 

 is cup-shaped, with a flat bottom, and is smooth 

 and hard, the thistle-down with which it is lined 

 being cemented with gum. The eggs are four, 

 sharply pointed, light cream-colour, and spotted, 

 chiefly at the large end, with chocolate. In the 

 breeding-time these Tyrants attack other birds 

 approaching the nest with great spirit, and have a 

 particular hatred to the Carrion Hawk, pursuing it 

 with the greatest violence through the air with angry 

 notes, resembling in sound the whetting of a scythe, 

 but uttered with great rapidity and emphasis. How 

 greatly this species is imposed upon by the Cow- 

 bird, notwithstanding its pugnacious temper, has 

 already been seen in my account of that bird. 



The Scissor-tails have one remarkable habit ; 

 they are not gregarious, but once every day, just 

 before the sun sets, all the birds living near together 

 rise to the tops of the trees, calling to one another 

 with loud, excited chirps, and then mount upwards 

 like rockets to a great height in the air ; then, after 

 whirling about for a few moments, they precipitate 

 themselves downwards with the greatest violence, 

 opening and shutting their tails during their wild 

 zig-zag flight, and uttering a succession of sharp, 

 grinding notes. After this curious performance they 

 separate in pairs, and perching on the tree-tops each 

 couple utters together its rattling castanet notes, 

 after which the company breaks up. 



