Oct 16, 2009 – Boldt Castle in the Thousand Islands on the Saint Lawrence River, New York – Richard T. Nowitz / Corbis

• Why is everyone wearing pink ribbons this month?
  To remind us to take care of our girls
• Ancient Romans ate flamingo tongues and thought them a rare delicacy.
  Ew! Just show me more pictures of flamingos
• Nobody knows for sure why flamingos stand around on one leg.
  But we do know why they’re pink
• Want to see flamingos in their natural habitat?
  There are baboons and lions, too

Flamingos or flamingoes are gregarious wading birds in the genus Phoenicopterus and family Phoenicopteridae. They are found in both the Western Hemisphere and in the Eastern Hemisphere, but are more numerous in the latter. There are four species in the Americas and two species in the Old World. Two species, the Andean and the James’s Flamingo, are often placed in the genus Phoenicoparrus instead of Phoenicopterus.

Evolution

The prehistory of the Phoenicopteriformes is far better researched than their systematic affinities (see below). An extinct family of peculiar “swimming flamingos”, the Palaelodidae, was initially believed to be the ancestors of the Phoenicopteridae. This is now rejected, as the fossil genus Elornis, apparently a true albeit primitive flamingo, is known from the Late Eocene, before any palaelodid flamingoes have been recorded. A considerable number of little-known birds from the Late Cretaceous onwards are sometimes considered to be flamingo ancestors. These include the genera Torotix, Scaniornis, Gallornis, Agnopterus, Tiliornis, Juncitarsus and Kashinia; these show a mix of characters and are fairly plesiomorphic in comparison to modern birds. They live for 6 years on average. There exists a fairly comprehensive fossil record of the genus Phoenicopterus. The systematics of prehistoric Phoenicopteriformes known only from fossils is as followed:

* Palaelodidae
o Adelalopus (Borgloon Early Oligocene of Hoogbutsel, Belgium)
o Palaelodus (Middle Oligocene -? Middle Pleistocene)
o Megapaloelodus (Late Oligocene – Early Pliocene)

* Phoenicopteridae
o Elornis (Middle? Eocene – Early Oligocene) – includes Actiornis
o Phoenicopteridae gen. et sp. indet. (Camacho Middle? – Late Miocene? of San José, Uruguay) – see Ubilla et al. (1990)
o Prehistoric species of Phoenicopterus:
+ Phoenicopterus croizeti (Middle Oligocene – Middle Miocene of C Europe)
+ Phoenicopterus floridanus (Early Pliocene of Florida)
+ Phoenicopterus stocki (Middle Pliocene of Rincón, Mexico)
+ Phoenicopterus copei (Late Pleistocene of W North America and C Mexico)
+ Phoenicopterus minutus (Late Pleistocene of California, USA)
+ Phoenicopterus aethiopicus

Relations
American Flamingos at Chester Zoo.
American Flamingo and offspring

The identity of the closest relatives of the flamingos is a rather contentious issue. 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 spoonbills and ibises of the Threskiornithidae were considered their closest relatives within this order. Nevertheless, relationships to the Anseriformes (waterfowl) were considered as well (Sibley et al. 1969), especially as flamingos and waterfowl are parasitized by feather lice of the genus Anaticola (Johnson et al. 2006), which are otherwise exclusively found on ducks and geese.

To reflect the uncertainty about this matter, flamingos began to be placed in their own order later on. Other scientists proposed flamingos as waders most closely related to the stilts and avocets, Recurvirostridae[citation needed]. The peculiar presbyornithids were used to argue for a close relationship between flamingos, waterfowl, and waders (Feduccia 1976), but they are now known to be unequivocal waterfowl with a peculiarly derived morphology paralleling waders and flamingos.

In recent years, molecular and anatomical studies have placed flamingos within their expanded (and certainly paraphyletic, as is now known) Ciconiiformes. On the other hand, since long it has been the grebes (Podicipedidae), rather than Ciconiiformes, ducks, or stilts, that were time and again indicated as the closest relatives of flamingos, and there is currently renewed interest in this hypothesis.

In a 2004 study comparing DNA sequences of intron 7 of the β-fibrinogen gene (FGB-int7), the Neognathae (all living birds except the ratites and tinamous) excluding waterfowl and Galliformes were shown to be divided into two subgroups of uneven size. The first and smaller one, Metaves, contains flamingos and grebes, alongside the hoatzin, pigeons, sandgrouse, the Caprimulgiformes, the Apodiformes, tropicbirds, mesites, sunbittern and kagu. Interestingly, most of these groups have traditionally been difficult to place on the family tree of birds. According to this study, all other birds belong to the second subgroup of Neoaves, the Coronaves (Fain & Houde 2004).

But their molecular data was insufficient to resolve inter-Metaves relationships to satisfaction; the flamingo FGB-int7 sequence is apparently most similar to that of some species of nighthawks, strongly suggesting a case of convergent evolution on the molecular level. The conclusions that one can draw from this study are twofold: first, that flamingos are Metaves (if that group is not based on molecular convergence, for which there are some indications), and second, that FBG-int7 is unsuitable to determine their relationships beyond that. It is interesting to note, however, that among all the groups which have been proposed as sister taxa of the flamingos, only the grebes are Metaves. The relationships of the flamingos still cannot be resolved with any certainty, but presently a close relationship with grebes appears somewhat more likely than other proposals. For this clade, the taxon Mirandornithes (“miraculous birds” due to their extreme divergence and apomorphies) has been proposed. In summary, all this confusion serves to show that all lines of “evidence” – molecular, morphological, ecological and parasitological – are liable to yield erroneous “proof” and that no method can be considered generally superior. Any future attempt to finally resolve the flamingos’ relationships, therefore, would have to employ total evidence to support it and carefully weigh the data against alternative proposals.