Isotope signatures of Carnivorans hair in the North-West of Russia: the role of diet, behavior and metabolism

The study presents the analysis of δ¹³C and δ¹⁵N values in the hair of several Carnivora species (brown bear, Eurasian lynx, wolf, red fox, European pine marten, least weasel, European polecat, stoat, otter) from the Vologda region (North-West of the Russian Federation). The value of δ¹³C varies from -27.9‰ to -20.4‰, δ¹⁵N – from 3.5‰ to 15.3‰.

This study shows that the trophic specialization of animals explains the width of variability in the isotopic ratios of carbon and nitrogen. The hair of semi-aquatic predator (otter) is depleted of the heavy carbon isotope compared to terrestrial carnivores. The ratio of heavy carbon isotopes in animal tissues is directly proportional to body weight and metabolic rate. Species with a narrow trophic specialization (Eurasian lynx, stoat, least weasel, otter) contain less ¹³C than species with a wider food spectrum (wolf, red fox, European pine marten, European polecat, brown bear). Animals with high motor activity (least weasel, stoat, European pine marten) contain less ¹³C in comparison with less mobile European polecat. When compared with data from museum collections, the value of δ¹³C in the hair of carnivorans from the southern and middle taiga has decreased by an average of 2.4 ‰ over the past 100 years.

The hair of animals that feed on aquatic prey (otter, European polecat) is enriched with a heavy nitrogen isotopes compared to predators that feed on phytophages (Eurasian lynx) and mainly plant food (brown bear). The hair of omnivorous species (European pine marten, red fox, wolf) and species that feed on small mammals (least weasel, stoat) are in an average position according to the δ¹⁵N value. The ability of animals to accumulate fat reserves to overcome long periods of food deficiency may be the reason for an increase in ¹³C (brown bear, European polecat) in tissues.