Interannual variations in feeding frequencies and food quality of greater flamingo chicks (Phoenicopterus roseus): evidence from plasma chemistry and effects on body condition.

Greater flamingos in southern Spain foraged in areas distant from a breeding site, spending 4-6 days in foraging areas between successive visits to the colony to feed their chicks. During four years, we took blood samples from chicks to ascertain whether there were interannual variations in several blood parameters, indicative of food quality and feeding frequencies. When the chicks were captured, 20-31% of them had their crops empty, indicating that not all chicks were fed daily. Additional evidence of variations in feeding frequencies was obtained from a principal component analysis (PCA) on plasma chemistry values, which also indicated that there were annual variations in the quality of food received by chicks. The association of cholesterol and glucose with some PC axes indicated that some chicks were experiencing fasting periods. Of all plasma metabolites considered, cholesterol was the best one to predict body condition. Greater flamingo chicks experiencing longer fasting intervals, as suggested by higher plasma levels of cholesterol, were in lower body condition.