122 BIRDS OF LA PLATA 
sight together. Thus, while in colour, habits, lan- 
guage, and even in its manner of soaring up like a 
rocket to let off its curious melody, the male is the 
most conspicuous of small birds, the female, acted 
on in an opposite direction by natural selection, has 
been, so to speak, effaced. While flying they do 
not look like birds of the same species: the male 
moves with wings rapidly fluttered, like a Starling, 
but with a slower, more laborious flight, and without 
deviating ; the female, in her eccentric movements in 
the air, reminds one of a large moth, driven from its 
hiding-place and flying about confused with the glare 
of noon. 
The nest is made of dry grass on the ground, so 
cunningly concealed that it is difficult to find. The 
eggs are four, white, spotted with reddish brown. 
When they have young I have never been able to 
detect the female flying about in search of food. 
All through the summer these birds are solitary, 
but when migrating in the autumn, though many 
are seen travelling singly and appear very conspicuous 
as they fly laboriously in a straight line, at an altitude 
of about twenty yards from the surface, others are 
seen making their journey in small flocks or parties 
composed of six to a dozen individuals. These are 
the males. The females travel separately, in twos 
or threes or singly, flying nearer to the earth, with 
frequent pauses when the wings cease beating, and 
intervals of gliding, also darting occasionally to one 
side, as if the bird had suddenly taken fright. 
