Diet Explains Interpopulation Variation of Plasma Carotenoids and Skin Pigmentation in Nestling White Storks

Abstract

Carotenoids have a dietary origin in birds, but mechanisms by which they are absorbed in the gut, transported in the blood, metabolized at various sites, and deposited in the integument remain poorly understood. Variation in both plasma carotenoid levels and external color may reflect different access to dietary carotenoids or individual physiological differences in the uptake and deposition of carotenoids. We compared total plasma carotenoid concentration in nestling white storks (Ciconia ciconia) from 11 Spanish colonies in two consecutive years. The main food item in one of the colonies was the red swamp crayfish (Procambarus clarkii), a recently introduced species. Storks in the remaining colonies ate a variety of foods but no crayfish. Total plasma carotenoid levels in the colony where crayfish were consumed were about five times higher than in any other colony. These differences were maintained after controlling for the significant interyear variability, as well as for sex, age, and body mass of birds. Skin pigmentation also differed, being intensely orange in storks that consumed crayfish but white (unpigmented) in the remaining individuals. With thin-layer chromatography (TLC) and electronic absorption spectroscopy, astaxanthin was confirmed as the major carotenoid in crayfish as well as in the plasma, skin, and body fat of crayfish-eating storks, whereas lutein was the main carotenoid in plasma samples from the other colonies. These results indicate that a newly available carotenoid in the environment, astaxanthin, can be absorbed in large quantities from the gut and be transported in the blood before deposition in different tissues.

Carotenoid availability in diet and phenotype of blue and great tit nestlings

“…However, both physiology and diet may differ between nestlings and adults, and it would be hazardous to extrapolate plasma carotenoid levels of nestlings from plasma carotenoid concentrations of adults. There is very little information available on plasma carotenoid levels in nestlings (Biard et al, 2005;Negro et al, 2000). Therefore, it is difficult to determine whether and how much carotenoids may be limiting for nestlings in our population.…”

“…Information on this topic is currently C. Biard, P. F. Surai and A. P. Møller very limited for nestling birds in the wild Negro et al, 2000;Slagsvold and Lifjeld, 1985;. In both species, increasing carotenoid intake had a positive effect on body condition (body mass relative to body size), but this was not paralleled by an effect on immune function.…”

Male Red-backed Fairywrens appear to enhance a plumage-based signal via adventitious molt

“…Juvenile birds can also convey condition via leg coloration, as in storks and raptors (Negro et al 2000, Casagrande et al 2009, Sternalski et al 2010, and the UV reflectance of nestling skin appears to be a signal that influences parental feeding (Jourdie et al 2004, Bize et al 2006. Juvenile American Coots (Fulica americana) display bright red skin on their head as well as orange feathers, which both appear to have evolved via parental favoritism for colorful chicks (Lyon et al 1994).…”

Stress response during development predicts fitness in a wild, long lived vertebrate

“…Because male and female white storks look alike, we resorted to molecular sexing of the birds (36). Nestling age, which ranged from 29 to 59 days old, was estimated according to a regression equation of age on wing chord (37). A body condition index was calculated as the individual's residual value from a regression of log 10 body mass on log 10 wing chord.…”