Explore the vast range of titles available.

The ability of the polar bear (U. maritimus) to kill and consume conspecifics is accepted, but the reasons behind this behavior and its prevalence remain unclear. Here, we report 14 cases of intraspecific killing, cannibalism, and aggressive behaviors among polar bears observed in seven instances in the Barents Sea and the Kara Sea on Frans-Josef Land, Novaya Zemlya, and Vize Island. All but one of the observations were made on land during the ice-free season. Perpetrators, when observable, were mostly thin. The hunger resulting from a failure to gain fat reserves in spring appears to motivate perpetrators, while bear aggregation on islands could facilitate successful intraspecific killing. Surprisingly, cases of intraspecific killing were observed even in years when sea-ice conditions in the previous spring were relatively good. In one case, the killing of a cub of the year in the spring by a large, fat male could hardly be explained by nutritional demands. This could be a case of sexually selected infanticide, as the killing of cubs during the mating season increases the male’s opportunity to breed.

AbstractBased on photo-trapping data, we estimated the attendance of mineral licks by reindeer in the mountain tundra of Kuznetsky Alatau Nature Reserve. We analyzed 15 877 pictures taken from January to September. We revealed obvious seasonal dynamics in the attendance of mineral licks by reindeer: animals visited mineral licks from mid-April to mid-September, most often in July. The maximum time the animals spent at a mineral lick was in April. We also found obvious patterns in reindeer daily activity: the animals visited mineral licks most often in the morning and the least often at night. However, the animals stayed at a mineral lick much longer at night than at any other time.

The results of studies of the mercury concentrations and stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) in the hair of polar bears (Ursus maritimus) inhabiting the islands of the Franz Josef Land archipelago, Novaya Zemlya archipelago, as well as the Yamal and Taymyr peninsulas are presented. It is shown that the levels of mercury accumulation in the hair of polar bears from the Franz Josef Land archipelago are characterized by values lower (about 2.0 mg/kg) than those in polar bears from the Canadian sector of the Arctic and commensurate with those of animals from Spitsbergen. A significant positive correlation was found between the mercury concentration and stable isotope (δ15N and δ13C) values. The minimum concentrations of mercury and isotope values (δ15N and δ13C) in the hair of bears from Yuzhny Island (Novaya Zemlya) may be a consequence of increased content of non-marine food in their diet rather than a result of climate change. The recorded mercury concentrations in the hair of bears indicate the absence of a threat to animal health.

AbstractReproduction of endangered species in captivity is an urgent problem for the conservation and restoration of biodiversity. For mammals, including felids, assessing and monitoring of pregnancy progression is fundamental for successful breeding. For the first time, changes in the concentrations of serum amyloid A (SAA), the main protein of the acute phase of inflammation in felines, were assessed during pregnancy in a domestic cat. It was found that changes in SAA concentrations in pregnant females are consistent: an increase to the middle of pregnancy (day 30) and a decrease to day 60. After parturition, the SAA concentrations in the blood of domestic cats increase. The litter size significantly affected the dynamic of SAA concentrations during the experiment, in particular, after parturition, the increase in its level was significantly higher in the females that gave birth to larger litters (from four to seven kittens).

For the first time, information is provided on the size of the home range of Siberian forest reindeer ( Rangifer tarandus valentinae ) of the Altai–Sayan population of Kuznetsk Alatau, the minimum distance that the deer passes per day, their changes, and changes of habitats during the annual cycle. Possible reasons for the cyclical use of the habitat by forest reindeer are discussed.

AbstractThe results of Amur tiger (Panthera tigris altaica) grouping recovery in the North-West of its distribution area are presented in this article. An analysis of tiger cubs specially trained for wildlife and released includes: establishing the spatial structure, the ability to find and hunt natural prey, the reaction to anthropogenic landscapes, facilities and infrastructure, and reproductive relationships. The young released tigers adapted to the wild successfully, developed a specifically actual spatial structure, hunted for wild prey, did not initiate carnivore-human conflicts, females brought offspring repeatedly, wild born younglings dispersed in this part of the range successfully. Thus, in the northwest of the distribution area of the Amur tiger, where in the 1970’s this species was totally exterminated, its grouping has presently recovered and stabilized. The total grouping numbers currently amount to at least 20 individuals. The restoration of the Amur tiger grouping is based on the technology developed and used by the Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences for orphaned tiger cub rehabilitation and training for wildlife.

Polymorphism of nine microsatellite loci in the Sikhote-Alin tiger population was analyzed in the modern and recent historical periods, using blood, excrement, and museum bone samples. Tests for excess heterozygosity to determine whether the population went through a period of low abundance and a low value of the Garza–Williamson coefficient indicated that such events were highly probable to occur in both recent and earlier history. The mean effective population size Ne of a current sample was 34.4 (95% confidence interval 17–106.8). This fact is of great interest in the contest of conservation and restoration of endangered large cat species.

The study presents the status and diversity of major histocompatibility complex (MHC) class I genes in the Far Eastern leopard ( Panthera pardus orientalis ). 20 alleles of MHC genes were obtained from 11 samples in total, 19 alleles were described for the first time for the species. A high diversity of alleles is shown at the level of individuals as well as at the population level. Comparison of MHC gene polymorphism in leopard subspecies showed that the genetic diversity of the Far Eastern leopard is not lower and even possibly higher, than observed of the African and Indian subspecies. The high allelic diversity of the Far Eastern leopard genes is supported by the positive selection affecting on the antigen-binding region of the protein product they encrypt. It is concluded that the low abundance of the Far Eastern leopard has not yet led to irreparable losses in the genetic potential of the population.

In the context of the Persian leopard restoration program in the Russian Caucasus, an in-depth analysis was conducted to understand the hunting behaviors of rewilded Persian leopards and evaluate the program’s effectiveness. From 2016 to 2023, GPS telemetry data from 14 leopards (8 males and 6 females) aged 20 months and older, released in the Western (WeC) and Central (CeC) Caucasus, were analyzed. Using cluster location analysis, we determined 243 kill sites categorized by prey-size into large, medium, and small classes. In the WeC, leopards exhibit a significantly higher proportion of large prey compared to the CeC (43%, N = 49 vs. 5.4%, N = 148, p < 0.01). There is no significant difference in the proportion of medium-sized prey, but there is a striking contrast in the proportion of small prey (WeC 16.2%, CeC 57.4% ( p < 0.01)). No significant differences were found in the time spent on prey between male and female leopards, regardless of the region. Female leopards capture their next prey 215 ± 184 hours (Mean ± SD; N = 131) after leaving the previous one, covering a distance of 46 ± 40 km (Mean ± SD, max 191 km). Male leopards, in contrast, take 265 ± 246 hours (Mean ± SD, N = 110) between kills, with a distance of 59 ± 60 km (Mean ± SD, max 366 km) between them. In the WeC, the kill rate for leopards are lower than in the CeC, with averages of a prey every 264 ± 273 hours and 62 ± 64 km ( N = 77) compared to 152 ± 172 hours and 47 ± 41 km ( N = 165), respectively. Leopards in the CeC spend significantly more time on kill sites with large and medium-sized prey compared to small prey. In contrast, leopards in the WeC show no significant difference in the time spent on prey of different size classes. This disparity is explained by the fact that large and medium-sized prey are more challenging to conceal and defend from competitors whose populations densities are higher in the WeC than the CeC. 20% of large and medium-size prey kill sites of leopard in the Western Caucasus have been visited by bears or wolves. This suggests that environmental factors and attractive high ungulate population densities may also play a critical role in shaping predator-prey dynamics and interspecific competition in the region. It is imperative to evaluate the availability of potential prey across different size classes, alongside with moderate levels of competitor populations. These factors can play a decisive role during the crucial first year of the leopard’s adaptation to life in the wild, ultimately determining the success of species restoration initiatives.

AbstractData are presented on the variation in the relationships of males and females in felids with different degrees of sexual dimorphism in body size. It was shown that, in the mating season of the Eurasian lynx, a species with the least sexual dimorphism, females determined the relationships with the partner to a large extent. These interactions were characterized by a high frequency of affiliative behavior and courtship elements, while the frequency of aggressive contact was very low. In species with a higher level of sexual dimorphism, the relationships of the partners were determined mainly by males.