F lamingos occur on four continents. From South America to the Caribbean, from the Mediterranean to South West Asia and over many parts of Africa. Whether on the wetlands of the High Andes or the vast alkaline lakes of East Africa’s Rift Valley, these birds will always astound us by their adaptations to life in harsh environments.
There are six species of flamingos in the world: the Andean Flamingo (Phoenicoparrus andinus), the James Flamingo (Phoenicoparrus jamesi), the Chilean Flamingo (Phoenicopterus chilensi), the Carribean Flamingo (Phoenicopterus ruber), the Lesser Flamingo (Phoenconaias minor) and the Greater Flamingo (Phoenicopterus roseus). They may at first glance look similar to each other, but certain features allow easy identification.
Vulnerable and threatened. Flamingos live in shallow brackish or salt-water lakes. They are vulnerable because these wetlands are threatened by developments for tourism, industry and agriculture.
The Greater flamingo. There are probably over half a million Greater Flamingos in the world. This species ranges over much of Africa where suitable habitat occurs, and across southern Europe into South West Asia, east to India and north to Kazakhstan (see distribution).
P rotected by law. The greater flamingos is listed at the Bern Convention (1979) and Bonn convention (1983) annexes as well as at the annex I of the Bird Directive 79/409/EEC of the European Union.
A flagship species for wetland conservation. Greater Flamingos’ breeding success varies greatly from one colony to another, according to the nature of the breeding site, climatic conditions and freedom from disturbance by humans and by predatory animals. In spite of the species’ relative abundance, the Greater Flamingo is vulnerable because of the limited number of favourable breeding sites.
Many of these sites are threatened by urban developments and/or drainage. If the foreseen climate change contributes, as predicted, to a rise in sea level, then this could jeopardize some of the existing sites, and consequently modify the dynamics of this population.
The survival of the Greater Flamingo in the Mediterranean depends on effective conservation measures in the Camargue, in Andalusia and at other colonies as well as maintaining a network of sites used outside the breeding season.
S ome huge breeding colonies. Greater flamingos are gregarious and breed in colonies of several hundreds to several thousands of individuals. Displaying begins and pairs start to form in winter, up to three months prior to breeding. The pairs are not faithful from one year to another, yet individuals of the same age tend to pair together (Cezilly & Johnson 1995). The display starts at the end of the autumn to form the pairs of the next summer.
After having chosen a favourable breeding site, flamingos build their nest, a mound of sand or mud 10 cm or more in height. The clutch is of one egg only which both partners incubate (for 1-4 days on the nest) during a period of 28-30 days.
At birth, the chicks are clad in a white down and their legs and bill are pink. After several days the down becomes grey, the legs and bill turning to black. They will not acquire their full pink plumage much before 4 years of age when they also become sexually mature.
The crèche. The chicks leave the nest when they are about one week of age. After about 12 days they gather in a crèche which most parents leave during the day, returning in the evening to feed their chick. They relocate their chick among hundreds or thousands of others by voice. The parent secretes a protein-rich liquid from its crop which the chick momentarily stores in its gizzard. Feedings last from 15-30 minutes and they will not forage for themselves much before they fledge at 75-80 days.
Marvellous travellers. At the end of summer many flamingos leave the Camargue and head south. For the newly fledged young, it is those birds in good body condition that will tend to fly south (Barbraud et al.. 2003). The choice of wintering site may also depend on the direction of the wind blowing when they disperse from the crèche (Nager et al. 1996).
Winter in the sun. Both adult and juvenile flamingos winter in large numbers in North Africa (Morocco, Algeria, Tunisia) and in West Africa (Mauritania, Senegal). Others may leave for the eastern Mediterranean (Turkey, Israel, Egypt). Young flamingos often remain for 2-3 years on or near their first wintering site, after which they converge on the breeding sites in spring in increasing numbers.
Nomads? Flamingo birthplace will not be inevitably become their first breeding site. The adults are not very faithful, and they can change breeding site form one year to the other. Thus it seems that the flamingos born in the Western Mediterranean belong all to only one and even population even if they were not born or do not reproduce at the same place. Such a population, made up from various inter-connected colonies is generally called a metapopulation.
W hy flamingos are pink? Flamingos were considered by the Egyptians as the incarnation of the Phoenix, a "fabulous bird, single in its species, which, said one, lived several centuries, and which, burned, reappeared from their ashes" (Littré). The Egyptians also used the shape of a Flamingo as a hieroglyph to mean the red colour and the Greeks used the word phoenix to indicate this same colour (Allen 1956).
Only 5 molecules, pertaining to the family of carotenoids contribute to this colouring, they are Echinenone (4-keto-β-carotene, orange), Canthaxanthine (4, 4' keto-β-carotene, red) which is prevalent in the blood and the feathers of the five species, Phoenicoxanthine (3-hydroxy-4,4' diketo-β-carotene, red), Astaxanthine (3,3' -dihydroxy-diketo-β-carotene, red) and Phoenicopterone (4-keto-α-carotene, orange) (Fox 1975).
These molecules, which are found in many brightly-coloured birds species, are the oxidized shapes of photosynthetic carotenoids that only plants can synthesize from simple molecules. These photosynthetic carotenoids are particularly abundant in the algae of the alkaline habitats that Flamingos occupy throughout the world. The Flamingos thus synthesize the pigments necessary for their colouring from carotenoids they find in their food, either by consuming unicellular algae and seeds of watery plants, these "first hand" carotenoids will have to be oxidized, either by consuming aquatic invertebrates such as Artemia salina or insect larvae. In the latter case, these “second hand" carotenoids are often already oxidized.
Sex appeal. The colouring of Flamingos may have been selected because it makes them cryptic on the reddish waters of salt lagoons which often take the same colour. This colouring perhaps also evolved like a secondary sexual character playing part in pair formation by signalling the quality of the individuals during displays. Indeed, in addition to their dye action, carotenoids have antioxidant, immuno-stimulating and detoxifying properties, and are powerful suppressor of free radicals. This observation resulted in the hypothesis that the evolution of colourings in birds would result from a positive selection for the individuals in good health signaled by the intensity of their colouring (Hamilton and Zuk 1982). This assumption is supported by a recent French study (Faivre et al. 2003) showing that in the black Blackbird Turdus merula, the activation of the immune system following an infection reduces the intensity of the orange colouring of the bill.
It was proposed that birds brilliantly coloured would be not only in better health but also ready to face infections. In this case, the individuals being able to redirect a surplus of carotenoids towards the plumage are those able to mobilize enough carotenoids for their immunity (Lozano 1994). An important assumption with this hypothesis is that it is difficult to get carotenoids in great quantity, so that there is a trade-off between immunity and colouring (Olson and Owens 1998). This assumption does not seem to be confirmed for all bird species and the high rate of carotenoids in circulation in the blood of the Flamingos suggests that these molecules are not limiting (Hill 1999).
If important variations of intensity of colouring of the plumage are visible in the Flamingos, so far no study was undertaken to understand the implications of these variations on the dynamics of pair formation.
Allen, R. P. (1956) The Flamingos: their life history and survival. National Audubon Society, New York, NY.
Barbraud, C., Johnson, A. R. & Bertault, G. (2003) Phenotypic correlates of post-fledging dispersal in a population of greater flamingos: the importance of body condition. Journal of Animal Ecology, 72, 246-257.
Cézilly, F. & Johnson, A. R. (1995) Re-mating between and within seasons in the Greater Flamingo Phoenicopterus ruber roseus. Ibis, 137, 543-546.
Faivre, B., Grégoire, A., Préault, M., Cézilly, F. & Sorci, G. (2003) Immune activation rapidly mirrored in a secondary sexual trait. Science, 300, 103.
Fox, D. L. (1975) Carotenoids in pigmentation , in J. Kear & N. Duplaix-Hall, eds. Flamingos. pp. 162-182. T & A D Poyser, Berkhamsted.
Hamilton, W. D. & Zuk, M. (1982) Heritable true fitness and bright birds : a role for parasites? Science, 218, 384-387.
Hill, G. E. (1999) Is there an immunological cost to carotenoid-based ornamental coloration. American Naturalist, 154, 589-595.
Lozano, G. A. (1994) Carotenoids, parasites and sexual selection. Oikos, 70, 309-311.
Nager, R., Johnson, A. R., Boy V., Rendon-Martos, M., Calderon J. & Cezilly F. (1996) Temporal and spatial variation in dispersal in the greater flamingo (Phoenicopterus ruber roseus). Oecologia, 107, 204-211.
Olson, V. A. & Owens, I. P. F. (1998) Costly Sexual Signals: Are Carotenoids Rare, Risky or Required? Trends in Ecology & Evolution, 13, 510-514.