Flamingo
Flamingos or flamingoes /fləˈmɪŋɡoʊz/ are a type of wading bird in the genus Phoenicopterus, the only genus in the family Phoenicopteridae. There are four flamingo species in the Americas and two species in the Old World.
Flamingo comes from Spanish flamenco, "with the colour of flame", in turn coming from Provençal flamenc from flama "flame" and Germanic-like suffix -ing, with a possible influence of words like Fleming. A similar etymology has the Latinate Greek term Phoenicopterus (from Greek: φοινικόπτερος phoinikopteros), literally "blood red-feathered".
Traditionally, the long-legged Ciconiiformes, probably a paraphyletic assemblage, have been considered the flamingos' closest relatives and the family was included in the order. Usually the ibises and spoonbills of the Threskiornithidae were considered their closest relatives within this order. Earlier genetic studies, such as those of Charles Sibley and colleagues, also supported this relationship. Relationships to the waterfowl were considered as well, especially as flamingos are parasitized by feather lice of the genus Anaticola, which are otherwise exclusively found on ducks and geese. The peculiar presbyornithids were used to argue for a close relationship between flamingos, waterfowl, and waders, but they are now known to be unequivocal waterfowl.
Six flamingo species are recognized by most sources, and these are generally placed in one genus. Two species, the Andean and the James's flamingo, are often placed in the genus Phoenicoparrus instead of Phoenicopterus.
Recent molecular studies have suggested a relation with grebes, while morphological evidence also strongly supports a relationship between flamingos and grebes. They hold at least eleven morphological traits in common, which are not found in other birds. Many of these characteristics have been previously identified on flamingos, but not on grebes. The fossil palaelodids can be considered evolutionarily, and ecologically, intermediate between flamingos and grebes.
For the grebe-flamingo clade, the taxon Mirandornithes ("miraculous birds" due to their extreme divergence and apomorphies) has been proposed. Alternatively, they could be placed in one order, with Phoenocopteriformes taking priority.
Flamingos often stand on one leg, the other leg tucked beneath the body. The reason for this behaviour is not fully understood. Recent research indicates 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. However, the behaviour also takes place in warm water. As well as standing in the water, flamingos may stamp their webbed feet in the mud to stir up food from the bottom.
Young flamingos hatch with greyish reddish 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 colored and thus a more desirable mate; a white or pale flamingo, however, is usually unhealthy or malnourished. Captive flamingos are a notable exception; many turn a pale pink as they are not fed carotene at levels comparable to the wild.
Captivity and age have been seen to have an effect on the blood composition of the American flamingo (Phoenicopterus ruber). A decrease in white blood cell numbers was predominate with age in both captive and free living flamingos, but captive flamingos showed a higher white blood cell count than free living flamingos. One exception occurs in free living flamingos with regards to white blood cell count. The number of eosinophils in free living birds are higher because these cells are the ones that fight off parasites which a free living bird may have more contact with than a captive one. Captive birds showed higher hematocrit and red blood cell numbers than the free living flamingos, and a blood hemoglobin increase was seen with age. An increase in hemoglobin would correspond with an adult's increase in metabolic needs. A smaller mean cellular volume recorded in free living flamingos coupled with similar mean hemoglobin content between captive and free living flamingos could show different oxygen diffusion characteristics between these two groups. Plasma chemistry remains relatively stable with age but lower values of protein content, uric acid, cholesterol, triglycerides, and phospholipids were seen in free living flamingos. This trend can be attributed to shortages and variances in food intake in free living flamingos.
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 carotenoids in their diet of animal and plant plankton. These carotenoids 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).
Flamingos are very social birds; they live in colonies whose population can number in the thousands. These large colonies are believed to serve three purposes for the flamingos: avoiding predators, maximizing food intake, and using scarce suitable nesting sites more efficiently. Before breeding, flamingo colonies split into breeding groups of between about 15 and 50 birds. Both males and females in these groups perform synchronized ritual displays. The members of a group stand together and display to each other by stretching their necks upwards, then uttering calls while head-flagging, and then flapping their wings. The displays do not seem to be directed towards an individual but instead occur randomly. These displays stimulate "synchronous nesting" (see below) and help pair up those birds who do not already have mates.
Flamingos form strong pair bonds of one male and one female, although in larger colonies flamingos sometimes change mates, presumably because there are more mates to choose from. Flamingo pairs establish and defend nesting territories. They locate a suitable spot on the mudflat to build a nest (the spot is usually chosen by the female). It is during nest building that copulation usually occurs. Nest building is sometimes interrupted by another flamingo pair trying to commandeer the nesting site for their own use. Flamingos aggressively defend their nesting sites. Both the male and the female contribute to building the nest, and to defending the nest and egg.
After the chicks hatch, the only parental expense is feeding. Both the male and the female feed their chicks with a kind of crop milk, produced in glands lining the whole of the upper digestive tract (not just the crop). Production is stimulated by a hormone called prolactin. The milk contains fat, protein, and red and white blood cells. (Pigeons and doves—Columbidae—also produce a crop milk (just in the glands lining the crop), which contains less fat and more protein than flamingo crop milk.)
For the first six days after the chicks hatch, the adults and chicks stay in the nesting sites. At around seven to twelve days old, the chicks begin to move out of their nests and explore their surroundings. When they are two weeks old, the chicks congregate in groups, called "microcrèches", and their parents leave them alone. After a while, the microcrèches merge into "crèches" containing thousands of chicks. Chicks that do not stay in their crèches are vulnerable to predators.
