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 continuous 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 on so scanty a fare this large bird not only supports itself, but becomes excessively fat. I spent half a winter in Patagonia at a house built on the borders of a small lake, and regularly every night a small flock of Flamingoes came to feed in the water about 200 yards from the back of the house. I used to open the window to listen to them, and the noise made by their beaks was continuous and resembled the sound produced by wringing out a wet cloth. They feed a great deal by day, but much more, I think, by night.
Where they are never persecuted they are tame birds, and when a flock is fired into and one bird killed, the other birds, though apparently much astonished, do not fly away. They are silent birds, but not actually dumb, having a low hoarse cry, uttered sometimes at the moment of taking flight; also another cry which I have only heard from a wounded bird, resembling the gobbling of a turkey-cock, only shriller. They are almost invariably seen standing in the water, even when not feeding, and even seem to sleep there; on land they have a very singular appearance, their immense height, in proportion to their bulk, giving them an appearance amongst birds something like that of the giraffe amongst mammals. To the lakes and water-courses in the midst of the grey scenery of Patagonia they seem to give a strange glory, while standing motionless, their tall rose-coloured forms mirrored in the dark water, but chiefly when they rise and pass in a long crimson train or phalanx, flying low over the surface.