Landscape REE anomalies and the cause of geophagy in wild animals at kudurs (mineral salt licks) in the Sikhote-Alin (Primorsky Krai, Russia).

To test the "rare earth" hypothesis of geophagy, geological and hydrogeochemical studies unparalleled anywhere in the world were carried out at kudurs (salt licks) in two districts in the Primorsky Krai, Russia. The mineral and chemical compositions of geophagic earth consumed by animals, the chemical composition of surface waters and vegetation, and the chemical composition of biological tissues of red deer (Cervus elaphus) were studied in this research. It was found that ultra-fresh surface and fontinal waters in the studied areas contain anomalously high concentrations of rare earth elements (REE), the sums of which exceeded the average values in the Primorsky Krai and worldwide by tenfold, and more. The presence of landscape REE anomalies is confirmed by elevated concentrations of these elements in vegetation. Using electron microscopy, it was determined that the sources of REE in landscape components are rocks containing secondary, readily soluble, REE minerals (hydrophosphates and fluorocarbonates). The study of the chemical composition of animal tissues showed the presence of significant concentrations of heavy REE (HREE) in the blood and brain, which indirectly indicates a high probability of animals developing stress reactions against the background REE-elementosis. Eaten earthy substances in both areas are represented by mixtures of smectite clays and zeolites with high ion-exchange properties. In the digestive tract of animals, such sorbents actively interact with the biological electrolyte, saturating it with sodium ions and absorbing HREE. The main meaning of geophagy is regulation of the concentration and proportion of REE in the body. Sometimes it manifests itself in intake of significant amounts of Na.

A study of kudurs used by wild animals located on the water sources high in REE content in the Caucasus Nature Reserve.

One of the theories explaining the reasons for geophagy, which was proposed earlier by the authors of the article, consists in the assumption that animals need rare-earth elements (REE). In order to test this hypothesis, we studied the chemical composition of spring waters in the territory of the Caucasus Nature Reserve at three kudurs along the Achipsta River, as well as at the Mamaevsky kudur (southwestern slope of the Pshekish mountain). At the Mamaevsky kudur, we also studied the chemical composition of earth consumed by animals, and the species, age and gender composition, seasonal and daily activity of ungulate animals-visitors of the kudur. It was determined that the most active visitors of the Mamaevsky kudur were European bison (Bison bonasus) with one activity peak during the rut, in July. The frequency of visits to the kudur by red deer (Cervus elaphus) was 4 times lower with the highest peak activity in April and a lower peak in August. Only in one of four water sources at the Mamaevsky kudur there was an elevated concentration of Na (by 7 times). In the other three the concentration was comparable to the local river water. The waters of two "sodium-free" springs had increased concentrations of REE (by 5-8 times). Geophagic earths near the Mamaevsky springs are decomposition products of siltstone and sandstone shale rocks of the Jurassic age consisting of clay minerals (illite mixed with smectite, and chlorites)-from 42 to 45%, and quartz and feldspar (in total up to 50%) mixed with Fe and Ca carbonates. The chemical composition of acid extracts (0.1 N HCl, pH = 1.0) from consumed earth showed the highest extractability of Ca and Fe. In trace elements, Sr, Ba, Zn, Cu, Ni, Co, V, light lanthanides, and Y are most actively extracted. Na is extracted at 0.03-0.1 g/kg. The sodium bicarbonate spring water consumed by animals at kudurs on the Achipsta River had Na contents 70-300 times, and REE contents 25-40 times higher than that in the river water. The revealed facts do not contradict the hypothesis that the desire for geophagy in animals in the Caucasus (in addition to the long-known "urge" for Na) can be also related to the properties of lanthanides group elements exchange in the body.

The seasonal sensitivity of brown bear denning phenology in response to climatic variability.

BACKGROUND: For brown bears (Ursus arctos), hibernation is a critical part of the annual life cycle because energy savings during hibernation can be crucial for overwintering, and females give birth to cubs at that time. For hibernation to be a useful strategy, timing is critical. However, environmental conditions vary greatly, which might have a negative effect on the functionality of the evolved biological time-keeping. Here, we used a long-term dataset (69 years) on brown bear denning phenology recorded in 12 Russian protected areas and quantified the phenological responses to variation in temperature and snow depth. Previous studies analyzing the relationship between climate and denning behavior did not consider that the brown bear response to variation in climatic factors might vary through a period preceding den entry and exit. We hypothesized that there is a seasonal sensitivity pattern of bear denning phenology in response to variation in climatic conditions, such that the effect of climatic variability will be pronounced only when it occurs close to den exit and entry dates. RESULTS: We found that brown bears are most sensitive to climatic variations around the observed first den exit and last entry dates, such that an increase/decrease in temperature in the periods closer to the first den exit and last entry dates have a greater influence on the denning dates than in other periods. CONCLUSIONS: Our study shows that climatic factors are modulating brown bear hibernation phenology and provide a further structuring of this modulation. The sensitivity of brown bears to changes in climatic factors during hibernation might affect their ability to cope with global climate change. Therefore, understanding these processes will be essential for informed management of biodiversity in a changing world.

Biochemical Content of Cambium of Abies nephrolepis Eaten by Bears on the Far East of Russia.

The peculiarity of bears behavior of stripping of bark is typical for all species. We have described the damage to trees, by Asiatic black bear (Ursus thibetanus) and brown bear (U. arctos) in Primorsky Krai and by brown bears on the Sakhalin Island during 1998-2015. In this study, we studied the damaged bark of the tree only in cases where it was clear that part of the cambium was eaten by bears. Cambium of species Abies nephrolepis is the most preferred for bear consumption in Primorsky Krai. We distinguished very large seasonal fluctuations in the amount of its consumption. The greatest interest of bears in this kind of food is in the summer time. We have analyzed the composition of the cambium of A. nephrolepis. These results suggest that the important purpose of the use of this kind of food is to restore and maintain the normal functioning of the intestines.