Keeping clean, with your friends!
One of the most noticeable aspects of bird social biology, that lots of animal behaviour scientists will tell you, is that birds who like each other tend to bath together (if they are a group-living species). And this is especially true of flamingos.
Flamingos are very fastidious birds and they enjoy nothing better than a good wash. The reason for this becomes evident when you look at the birds' natural habitat. Whilst flamingos are perfectly happy to wade around, and feed, in highly caustic water from soda lakes, they do not like to have particles of the salts from these lakes build up on their plumage. This could potentially be very dangerous for the flamingos, impairing their ability to keep themselves waterproof, insulated and flying efficiently. Consequently, flamingos will break away from their main flock and bathe in shallow, fresh water areas to ensure their feathers are kept in tip-top condition. Whilst we don't keep the birds in nasty, soda-ridden water at WWT Slimbridge, they still indulge in frequent bathing activity; and pairs, trios or quartets of "flamingo friends" can easily be watched giving their feathers a good dunking. Here is a short clip of the bathing sequence of an Andean flamingo.
[yframe url='http://www.youtube.com/watch?v=ScBUgjRz8Ns']
And here is a pair of Andean flamingos that are regularly seen together, preening and smoothing down their feathers after they have finished washing. Look out for which birds, in all of the flamingo flocks, that might be close pals by seeing which ones are having a wash in the same bit of their pond!