Respiratory function of a unit of blood volume in the Little Auk (Plautus alle) and the arctic tern (Sterna paradisaea)

The indices of red blood were determined in nestlings and adults of Plautus alle and adults of Sterna paradisaea. All measured parameters varied significantly, but the amount of Hb per unit area of erythrocytes did not change over the nestling development of P. alle. In adult P. alle, S. paradisaea and 12 compared species of birds from the temperate zone, the amount of Hb per unit area of erythrocytes was very close. The mechanism determining the level of the respiratory function of a unit blood volume in birds is similar, but differs from that in mammals.