Ecological and morphological analysis of the cardiac index seasonal dynamics of the Chuvash Republic sedentary and migratory birds

The following paper describes the results of seasonal dynamics study of the cardiac index of sedentary and migratory species of the Corvidae birds on the territory of the Chuvash Republic. The objects of the research were sedentary, nomadic and migratory species of the Corvidae birds: magpie, jackdaw, rook and gray crow. The work is based on the materials of the field and laboratory studies, which were conducted in the spring and autumn of 2016-2019 in the Chuvash Republic. The parameters of the cardiac index of grey crows, magpies, rooks and jackdaws were studied and birds with the lowest body mass and the most developed flying muscles, as well as migratory birds had the highest values of this indicator. When determining the cardiac index in spring and autumn, all the considered bird species had significant inter-seasonal differences of the studied parameter. It may be due to seasonal fluctuations in the activity and body mass of the birds. Of all the studied bird species only the rook had the highest seasonal variability of the cardiac index. The magpie had the smallest differences between spring and autumn values of the cardiac index, as they lead the most sedentary lifestyle compared to the rook, the crow and the jackdaw.