Testing a Non-Invasive Method of Stress Assessment in the Wild Boar (Sus Scrofa L., 1758; Artiodactyla)

The possibility of applying a non-invasive method of stress assessment in the Wild boar (Sus scrofa L., 1758) based on the overall concentrations of immunoreactive substances bound by antibodies to cortisol (C–IRS) in animal feces was investigated using the ELISA test system “Cortisol” (“Khema”, Russia). A physiological validation of the method showed that the measurements taken from the animal feces reflected the hormone-producing function and secretory activity of the adrenal cortex. Two samples of feces from wild boars living in semi-free conditions in the Republic of Karelia (LLC “Hunting Farm Chyornye Kamni”, Sortavala District) with high (n = 14) and low (n = 11) levels of stress factor exposure were compared. Fecal samples were collected at feeding sites in two enclosures for semi-free animal keeping. At the time of the study, repairs were being conducted in the first enclosure, and traces of predators (wolves) were found. Additionally, the long-term average density of wild boars in the first enclosure was significantly higher than in the second (14.1 and 1.57 individuals/km2, respectively). Wild boars from the first enclosure showed higher concentrations of C–IRS in their feces compared to those from the second, indicating a higher level of stress among the wild boars in the first enclosure. Potential causes of anxiety for the animals may include high population density, the presence of predators, and anthropogenic influences (repair work, vehicle traffic). The results of the study demonstrated that analyzing the C–IRS concentrations in the feces of wild boars is suitable as a non-invasive method for animal stress assessment and can be used in monitoring studies of wild boar populations.