In this review the allometric relations of different blood parameters
to body mass in birds are given. The following parameters are treated:
physical and chemical properties, leucocytes (number, differential bl
ood count, Arneth counts, ontogeny), erythrocytes (number, length, wid
th, volume, hemoglobin content, ontogeny, different forms during embry
ogeny, maturation), blood glucose, hematocrit, hemoglobin, MCV, MCH, M
CHC, plasma protein concentration, thrombocytes (number, ontogeny) and
blood groups. The influence of different endogenous (sex, hormones, a
ge, laying cycle, breeding, etc.) and exogenous factors (temperature,
activity, diurnal cycle, geographical altitude, climate, etc.) is disc
ussed. The taxonomic differentiation in different systematic orders wi
thin the birds is presented. Compared to mammalia only very few differ
ences characterize bird blood: The oval erythrocytes are nucleated, bl
ood glucose level is twice as high, plasma protein content is consider
ably lower and the (nucleated) thrombocytes are as big as the other le
ucocytes.