46 BIRDS OF LA PLATA 



active, overflowing with life and energy, their im- 

 petuous notes and motions giving one the idea that 

 they are always in a state of violent excitement* The 

 male has a loud, startled chirp, also a song composed 

 of eight or ten notes, delivered with such vehemence 

 and rapidity that they run into each other and sound 

 more like a scream than a song. There is not a more 

 clever architect than this species ; and while many 

 Synallaxes are laboriously endeavouring to show how 

 stately a mansion of sticks a little bird can erect for 

 itself, the Screaming Finch has successfully solved 

 the problem of how to construct the most perfect 

 nest for lightness, strength, and symmetry with the 

 fewest materials. It is a small cup-shaped structure, 

 suspended hammock-wise between two slender up- 

 right branches, to which it is securely attached by 

 fine hairs and webs. It is made of thin, pale-coloured, 

 fibrous roots, ingeniously woven together reddish or 

 light-coloured horsehair being sometimes substi- 

 tuted ; and so little material is used that, standing 

 under the tree, a person can easily count the eggs 

 through the bottom of the nest. Its apparent frailness 

 is, however, its best protection from the prying eyes 

 of birds and mammals that prey on the eggs and young 

 of small birds ; for it is difficult to detect this slight 

 structure, through which the sunshine and rain pass 

 so freely. So light is the little basket-nest that it may 

 be placed on the open hand and blown away with the 

 breath like straw ; yet so strong that a man can 

 suspend his weight from it without pulling it to 

 pieces. The eggs are three in number, white and 



