Haematocrit values of breeding Red-billed queleas Quelea quelea (Aves: Ploceidae) in relation to body condition and thymus activity

In a Red-billed quelea colony in north-eastern Nigeria that was later abandoned as a result of the poor nutritional condition of the adults, laying females showed low haematocrit values compared with normal pre-breeding haematocrit levels but nestbuilding males did not. In females the low haematocrits were correlated with extremely low levels of reserve lipid and labile protein but males in equally poor condition did not have such low haematocrits. This difference must result in some way from the additional nutritional burden for females of mobilizing sufficient protein to form eggs. Earlier observations of massive red blood cell production in the thymus of queleas during incubation suggest that low haematocrits, indicating anaemia, may be a normal occurrence in queleas during breeding, and were not peculiar to this abnormal abandoned colony.