Comparative Study of Blood Volume in Representative Aquatic and Nonaquatic Birds

Abstract

Plasma volume (T-1824 dye method), hematocrit value, hemoglobin concentration and erythrocyte count were measured in several species of aquatic and nonaquatic birds, and from these data total blood and erythrocyte volumes were calculated. Total blood, plasma and erythrocyte volumes, relative to body weight, were greater in aquatic than in nonaquatic birds. Hemoglobin concentration was generally higher in the aquatic group, but pigeons had the highest mean concentration. No significant differences in hematocrit value or erythrocyte count between aquatic and terrestrial birds were observed. Male white leghorns had higher hemoglobin concentrations than hens and male ring-necked pheasants had larger total blood volumes than females, but no other sex differences in blood composition were observed. The essentially identical blood pictures in diving and dabbling ducks indicate that differences in habits of underwater progression between these two groups cannot be explained by differences in blood composition. Of the terrestrial birds studied, the pigeon, a strong flier, had a blood picture comparable to that found in typical aquatic birds. Similar vascular adaptations may suffice for this type of flight and for underwater swimming.