Abstract
The aim of our study was to analyse red blood cells from the high-altitude avian species alpine accentor (Prunella collaris). We caught 79 alpine accentors in the High Tatra Mountains (the West Carpathians, Slovakia) from 2001 to 2008. Blood samples were collected from the vena ulnaris cutanea. The cells and nuclei of juveniles tend to be wider and larger while adults, especially males, tend to have elongated (narrow) cells. The largest erythrocytes were found in winter and the smallest in summer, in June. Red blood cells with larger, elongated nuclei but overall smaller in size occurred at the beginning and the end of the breeding season, while larger, rounded cells with smaller nuclei were found in the middle of the breeding season. This kind of reshaping of erythrocytes of alpine accentors in summer is probably a response to hypoxia and elevated summer temperature in high mountains. As regards the length/width ratio, in August and September, erythrocytes were more elongated (both cell and nucleus) than in the other months. This study is probably the first assessment of seasonal effects on size and shape of red blood cells of bird species permanently living and breeding at high altitudes of the Palearctic mountains.
Highlights
The environmental stressors on endothermic vertebrates at high altitude are well understood: cold and hypoxic conditions interact to create a metabolically challenging environment within which constant energy production must be maintained in the face of reduced oxygen availability and increased thermal stress (Cheviron et al 2008)
Red blood cells with larger, elongated nuclei but overall smaller in size occurred at the beginning and the end of the breeding season, while larger, rounded cells with smaller nuclei were found in the middle of the breeding season
Size and shape related to size In altricial birds Red blood cells (RBC) of juveniles are generally rounder, with less oval to round nuclei, and polychromatophilic cytoplasm
Summary
The environmental stressors on endothermic vertebrates at high altitude are well understood: cold and hypoxic conditions interact to create a metabolically challenging environment within which constant energy production must be maintained in the face of reduced oxygen availability and increased thermal stress (Cheviron et al 2008). The alpine accentor Prunella collaris (Scopoli, 1769) is a high-altitude bird species. It breeds in the alpine zone of mountains in the West Palearctic at an approximate elevation range of 1800 to 5000 m above sea level (asl), but is found in the West Himalayas and Pakistan at 3600–5000 m asl and is observed at almost 8000 m asl on Mount Everest (Hatchwell 2005). Regardless of region, alpine accentors are closely associated with high mountains where habitats are not continuous, but rather have a patchy distribution. Because the alpine accentor is highly adapted to the high-mountain environment, hypoxia and low temperature might play an important role in the development and evolution of the respiratory and cardiovascular system of this bird species. Reconstruction of the biogeographic history of Prunellidae by Drovetski et al (2013) suggests that the origin of the species and its
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