Metabolic fractionation, storage and display of carotenoid pigments by flamingoes

Abstract

1. 1. Captive specimens of the brilliantly coloured American or West Indian flamingo, Phoenicopterus ruber, and its paler South American relative, Phoenicopterus chilensis, gradually lose the red pigmentation of the exposed skin, and of the feathers through moulting, unless fed a diet rich in carotenoids. 2. 2. Analyses of the brightly coloured feathers, exposed leg-skin, egg-yolk, blood plasma and various internal organs from captive flocks have revealed rich stores of carotenoids, including prominently canthaxanthin and varying amounts of astaxanthin in some sites, and numerous other apparently oxidized members not yet completely characterized. 3. 3. Astaxanthin, present in adult feathers of P. ruber and in the exposed leg-skin of both species (as an ester in P. chilensis), was not detected in the plasma or in any internal organs or tissues examined, save for suspected traces in but one of several blood-filled shafts of young pin-feathers examined chemically directly after plucking from living adult P. ruber. The small, rare species, Phoenicoparrus jamesi, deposits both canthaxanthin and astaxanthin in its feathers. 4. 4. The pale and always largely fluid faeces, taken from the intestines of freshly dead adult P. ruber and P. chilensis specimens, yielded no carotenoids, or at times only bare traces of yellow pigment, to extracting solvents. 5. 5. Aerobic and anaerobic bacteria from P. ruber's gut exhibited dehydrogenase activity on numerous pure substrates, and altered astacene chemically. 6. 6. Representative concentrations of total carotenoids, in mg per 100 g dry weight, were found to be approximately as follows, in four prominent depots Tarsal skin 270: Feathers 32: Blood plasma 5: Yolk 4. 7. 7. Newly hatched, white or greyish-downed chicks were without detectable carotenoids in any tissue examined. Their short, oedematous legs show bright pink to red colours from the presence of haemoglobin beneath the thin, naked skin. However, in about 8 days, as a chick prepares to leave its nest, wherein it earlier received intermittent shading by a hovering parent or by sitting on its legs, to migrate into regions of exposure to full sunlight, this skin turns black with melanin deposits. Red carotenoids are later deposited in new feathers and in the naked leg-skin, gradually replacing melanin in the latter as the young birdd grows toward adulthood. © 1962.