A COMPARATIVE ANALYSIS OF THE PLUMAGE MASS OF THE DEMOISELLE CRANE (ANTHROPOIDES VIRGO L. 1758) AND THE EURASIAN CRANE (GRUS GRUS L. 1758) (AVES, GRUIFORMES)

The distribution of the mass of both down and down feathers along the pterilia of the Demoiselle crane and the Eurasian crane has been described for the first time. Fundamental differences in the plumage structure of these closely related species living in the summer in different climatic zones have been revealed. On the ventral side of the body of the Eurasian crane, the proportion of down and down feathers is significantly greater than on the dorsal side, whereas the proportion of the downy part of the contour feather vane is 1.5 to 2 times less. The additional down feather exceeds 2 cm, as a rule. Such a distribution of fluff ensures effective thermoregulation in this cold- and moisture-resistant species. In the Demoiselle crane, the abundance of down and down feathers on the ventral side of the body is 3 times less than on the dorsal side and 2 times less than in the Eurasian crane. On the dorsal side of the body, the proportion of fluff is almost 1.5 times greater than that of the Eurasian crane. The proportion of the downy part of the contour feather vane on feathers of different sizes on the dorsal and ventral sides is approximately the same. The contour feather contains predominantly umbilical fluff. Such a structure of the integument on the ventral side of the body allows the Demoiselle Crane, an inhabitant of hot climates, to better ventilate the thickness of the plumage and to increase the heat transfer of the body to the environment. The large proportion of downy structures on the dorsal side prevents heat from penetrating the skin.