192 BIRDS OF LA PLATA 
They usually go in floes of about forty or fifty 
individuals, and fly rapidly, keeping very close 
together. On the ground, however, they are always 
much scattered, and are so reluctant to rise that 
they will allow a person to walk or ride through the 
flock without taking wing, each bird creeping into 
a little hollow in the surface or behind a tuft of grass 
to escape observation. During its winter sojourn 
on the pampas the flock always selects as a feeding- 
ground a patch of whitish argillaceous earth with a 
scanty, withered vegetation; and here, when the 
birds crouch motionless on the ground, to which 
their grey plumage so closely assimilates in colour, 
it is most difficult to detect them. Ifa person stands 
still, close to or in the midst of the flock, the birds will 
presently betray their presence by answering each 
other with a variety of strange notes, resembling the 
cooing of Pigeons, loud taps on a hollow ground, 
and other mysterious sounds, which seem to come 
from beneath the earth. 
In the valley of Rio Negro I met with a few 
of these birds in summer, but could not find their 
nests. 
Durnford, however, who found them breeding 
in Chupat at the end of October, tells us that 
the nest is a slight depression in the ground, some- 
times lined with a few blades of grass. ‘* The eggs 
have a pale stone ground-colour, very thickly but 
finely speckled with light and dark chocolate mark- 
ings; they have a polished appearance, and measure 
1.3 by .8 inch.” (Ibis, 1878, p. 403.) 
