Flamingos often stand on one leg, the other tucked beneath the body. The reason for this behavior is not fully understood.
Some suggest that the flamingo, like some other animals, has the ability to have half of its body go into a state of sleep, and when
one side is rested, the flamingo will swap legs and then let the other half sleep, but this has not been proven. Recent research has indicated that standing on one leg may allow the birds to conserve more body heat, given that they spend a significant amount of
time wading in cold water. As well as standing in the water, flamingos may stamp their webbed feet in the mud to stir up food
from the bottom. Or perhaps they just like to stand onm one leg at a time.

Young flamingos hatch with grey plumage, but adults range from light pink to bright red due to aqueous bacteria and beta carotene
obtained from their food supply. A well-fed, healthy flamingo is more vibrantly coloured and thus a more desirable mate; a white
or pale flamingo, however, is usually unhealthy or malnourished.

Flamingos filter-feed on brine shrimp and blue-green algae. Their beaks are specially adapted to separate mud and silt from the
food they eat, and are uniquely used upside-down. The filtering of food items is assisted by hairy structures called lamellae
which line the mandibles, and the large rough-surfaced tongue. The pink or reddish color of flamingos comes from carotenoid
proteins in their diet of animal and plant plankton. These proteins are broken down into pigments by liver enzymes.
The source of this varies by species, and affects the saturation of color. Flamingos whose sole diet is blue-green algae are darker
in color compared to those who get it second hand (e.g. from animals that have digested blue-green algae). Zoo-fed flamingos, who often lack the color enhancer in their diet, may be given food with the additive canthaxanthin.

Lesser Flamingo Phoenicopterus minor in Chilika, Orissa, India. Photo: © J.M. Garg

Flamingos are very social birds that live in colonies that can number in the thousands. These large colonies are believed to serve
three purposes for the flamingos: predator avoidance, maximizing food intake, and exploiting scarce suitable nesting sites.
The most basic and stable social unit of flamingos are pair bonds which are made up of one male and one female. The bond
between them tends to be strong; however, in larger colonies (where there are more mates to choose from), mate changes will
occur. In pair bonds, both the male and the female contribute to building the nest for their egg and defending it.

Before breeding, flamingo colonies split into breeding groups of around 15-50 birds. Both males and females in these groups
perform synchronized ritual displays. These displays serve to both stimulate synchronous nesting and establish pair formation for
birds that do not already have mates. A flamingo group stands together and display to each other by rasing neck, followed by
calling with head-flagging and then wing flapping. The displays do not seem to be directed towards an individual but instead
occur randomly.

Flamingos will viciously defend their nesting sites and young. After the chicks hatch, the only parental expense is feeding.
Flamingos produce a crop milk, like pigeons and doves, due to the action of a hormone called prolactin (see Columbidae).
It contains more fat and less protein than the latter does, and it is produced in glands lining the whole of the upper digestive tract,
not just the crop. Both parents nurse their chick, and young flamingos feed on this milk, which also contains red and white blood
cells. In the first six days, the adults and chicks stay in the nesting sites. At around seven to twelve days the chicks begin to move
and explore their surroundings. After two weeks, the chicks join groups called "microcrèches" and their parent soon leave them in
these groups. Later, many microcrèches come together to form crèches which contain thousands of chicks. Chicks that do not
stay in their crèches are vulnerable to predators.