Assessment of Blood Parameters in Free-Ranging Red Deer (Cervus elaphus) from the Eastern Carpathians Between Autumn and Early Winter.

Understanding physiological variability in wild ungulates is essential for ecological monitoring and sustainable wildlife management. This study aimed to examine whether sex and season (autumn vs. early winter) significantly influence hematological and biochemical parameters in free-ranging red deer (Cervus elaphus) from the Eastern Carpathians, Romania. A total of 40 legally harvested adult individuals (20 males, 20 females) were included, and blood samples were collected post-mortem under standardized conditions to minimize pre-analytical variability. Hematological parameters (WBC, RBC, HGB, HCT, PLTs) and serum biochemical markers (glucose, urea, total cholesterol, triglycerides, total protein) were analyzed using automated veterinary analyzers. Statistically significant sex-related differences were found in hematocrit during autumn and hemoglobin concentration during winter, with higher values in males. Seasonal variation within sex groups was not significant but indicated a physiological trend toward hemoconcentration in winter. Biochemical values remained within reference ranges and showed no significant differences across groups. Pearson's correlation analysis revealed a strong association between hematocrit and urea, and moderate correlations were observed between WBC and glucose, suggesting links between oxygen transport, protein metabolism, and energy balance. Environmental factors such as reduced food availability and temperature shifts during winter likely contribute to these physiological adjustments. These results provide baseline data for the physiological assessment of red deer populations and support the development of ecological health indicators in wildlife monitoring programs. Future studies incorporating hormonal and immunological biomarkers across multiple seasons are encouraged to further understand adaptive responses in cervids.