128 BIRDS OF LA PLATA 
salt-lake—which, however#fiad been abandoned by 
the birds before my visit. The nest there, as in other 
regions, was a small pillar of mud raised a foot or 
eighteen inches above the surface of the water, and 
with a slight hollow on the top; and I was assured 
by people who had watched them on their nests that 
the incubating bird invariably sits with the hind 
part of the body projecting from the nest, and the 
long legs dangling down in the water, and not tucked 
up under the bird. 
On the Rio Negro I found the birds most abundant 
in winter, which surprised me, for that there is a 
movement of Flamingoes to the north in the autumn 
I am quite sure, having often seen them passing 
overhead in a northerly direction in the migrating 
season. I have also found the young birds, in the 
grey plumage, at this season in the marshes near to 
Buenos Ayres city, hundreds of miles from any 
known breeding-place. Probably the birds in the 
interior of the country, where the cold is far more 
intense than on the sea-coast, go north before winter, 
while those in the district bordering on the Atlantic 
have become stationary. 
The Flamingo has a curious way of feeding: it 
immerses the beak, and by means of a rapid con- 
tinuous movement of the mandibles passes a current 
of water through the mouth, where the minutest 
insects and particles of floating matter are arrested 
by the teeth. The stomach is small, and is usually 
found to contain a pulpy mass of greenish-coloured 
stuff, mixed with minute particles of quartz. Yet 
