In spring, not only the nature wakes up in the mountains of the Caucasian Reserve, but also the bears. In his interview, Professor Anatoly Kudaktin, Doctor of Biological Sciences, Chief Researcher of the Caucasian Reserve tells why the animals lose weight, why they become vegetarians and how bears-foreigners behave.
- The last winter was very snowy in the mountains around Sochi and the skiing season lasted here until May 10. How did it affect the bear hibernation? Have the bears already come out of hibernation?
- This winter did not coincide with the usual calendar schedule - until mid-January, it was very warm and the bears denned rather late. The representatives of the nominal morph were the first to leave for the denning areas, including she-bears that should give birth to bear cubs, and large adult he-bears. As usual, they went to the highlands, came to the dens in advance to wait for a lot of snow to be near them so that the snow would hide the traces of their stay from those who could disturb their sleep. And, despite the vagaries of nature, the bears came out of hibernation in due time, which has been confirmed by many years of observations. The he-bears emerged from their dens between March 5 and 10. And she-bears with the bear cubs woke up according to their own ‘schedule’ - from April 10 to April 15. I analyzed the results of observing the bears at the Reserve since 1928, and every year, the she-bears appeared at the same time. All of them normally emerge from hibernation before April 20. The explanation is that the bear cubs born in winter are grown up by this time, the bears are very short on space in their dens, so, they need to go out into the world, show the babies the first green grass that can be used as complementary food in addition to their mother’s milk.
But in recent years, a population of synanthropic bears has formed, they are smaller. There are up to 50 such individuals at the Caucasian Reserve. They do not climb up high in the mountains, they live closer to humans. Some of these bears either hibernate very little, they may ‘sleep’ for a week or two while the snow is deep, or do not hibernate at all. They go down to the settlements. Their traces are in the Krasnaya Polyana area, on the right side of the Mzymta River, in the Chvizhepse, Moldovka, Kepshi areas, along the canyon near Solokh-Aul and Lazarevskaya. These animals have their own lifestyle, their own peculiarities that distinguish them from the bears of the nominal morphs, which wake up after months of hibernation high in the mountains. And we still have to think about how our relationship with this group of bears will develop in future.
- When a bear emerges from hibernation, how does it start the summer cycle of a bear’s life?
- The traces of bears show that the he-bears in the highlands have already emerged from hibernation, but behaved a little different way than earlier. Usually, when they ‘wake up’ they immediately go through the mountain passes to the places where they occupy and scent-mark ‘their’ territory, and where their mating rituals will take place from mid-May to mid-June. Due to the snowy winter, the he-bears went later to the lower hillsides where they were still able to find beech nuts and acorns. Having had a snack, some of the bears have already gone to the mountain passes. They check the avalanche channels where they can find the Caucasian wild goats in the snow that died in the winter. According to many years of research, we know that in the snow avalanches in our mountains, up to 300 wild goats perished in the winter. The bears know this too, they are able to dig dead animals from a depth of 5-6 metres. This is their first spring food, since there is still no vegetation in the highlands. In nature, everything is wise and logical. After winter, all feeding and digestive functions in bears changed so that by the mating season, the he-bears can use up all the remaining fat accumulated since autumn, otherwise they are not able to take part in mating rituals. The matter is that in a fat he-bear, the processes go that reduce its reproductive functions. The meat of the dead wild goats and the first vegetation help lose the weight and change the physiological processes. This is how the alpine bears of nominal morph behave in spring.
The synanthropic bears have their own habitats, trails, rules and places for mating ritulas. They prefer low-mountain slopes, thickets of cherry laurel along the rivers, where they meet for their mating rituals. We learn about the life of such bears by their traces and some marks. Many ‘scavengers’ dumpster diving near the houses are among these bears. Some she-bears of this morph make dens in the tree hollows and their cubs are born there. Others arrange winter dens in the karst cavities, in caves. It is a comfortable place with a microclimate and constant humidity. This is similar to the inherited memory from those cave bears that once lived in the Caucasus. We want to install an automatic camera in such a cave that will respond to motion. When an animal comes, the camera turns on, when it leaves - the camera turns off. We are working on this experiment with our students, and the technical preparations are underway. I think we can learn a lot about the life of these bears.
- The bear cubs emerge from their dens for the first time. How does the big world meet them? What enemies do they have? How do they take the first steps to live on their own after leaving their den?
- After leaving the den, she-bears with the cubs usually do not rush to move anywhere, they choose warm hillsides where the first vegetation appears but don’t roam very far and stay close to their den so that the newborns are not attacked. The cubs have a lot of enemies like wolves, large birds of prey, and large adult he-bears can kill a bear cub. And the cubs are still very small and their weight is no more than two or three kilogrammes. At this age, a bear cub can eat both milk and grass, and later on, it gets gradually accustomed to eat meat and various vegetable food. By May, the bear cubs gain up to 9-10 kg and becomes more independent. By September, they should weigh at least 25 kg so that by winter, they would be ready to hibernate with their mother in a den, and only after a year and a half, they will live on their own.
- It turns out that the bear cubs, leaving the den, live like vegetarians and later on, they turn into predators?
- In nature, I repeat, everything is reasonably arranged. The bear body goes through various stages of its formation. First, a bear cub feeds on milk, then on the tender fresh vegetation, it cannot even eat a nut or acorn yet, and some time later, rotten, and, therefore, soft meat may be in its diet. Moreover, not all bear cubs, even those who ate meat when they were young, become predators.
So, we told that many he-bears go through the mountain passes after hibernation, look for dead animals in the mountains and eat them. But the grass grows, and they feed on it, and then some of the he-bears forage for goats or young wild goats, deer. I saw how a bear found a dead Caucasian tur in an avalanche and was eating it, and another bear passed nearby, felt the meat smell, but did not react and kept on eating the grass. They are like people: some are meat eaters, some eat various food and the others are vegetarians. At our Reserve, the percentage of predators is much lower than in other regions of Russia for one reason - the Caucasian bears have a lot of vegetable food all year round. In the northern forests, bears eat lingonberries, cranberries, even rotten stumps with insects to gain fat for the hibernation period. We do not have a food choice problem as a lot of berries and fruits, chestnuts and nuts, herbs and root crops are available. This allows our bears to be vegetarians.
- You told about how he-bears prepare for mating rituals. Do she-bears also prepare for the rituals?
- Unlike the he-bears, she-bears do not want to lose weight. Moreover, not all of them take part in the mating rituals. As for the bears of nominal morph, she-bears with newborn cubs usually do not take part in these rituals. The breakup of ‘family ties’ occurs later when the bear cubs are one and a half years old. Usually, the cubs live with their mother for two winters. In the second spring, they can already start living on their own, even arrange a den for themselves. But they can keep on living with their mother if it does not take part in the mating rituals.
The situation is different with the small size Caucasian bears’ population living in low mountains. She-bears who gave birth to cubs in winter can participate in the mating rituals the same year and give birth to cubs. In such cases, the mother leaves the cubs for a short time, chooses a partner, and then returns to her cubs. It keeps on living with them, taking care of them, can hibernate with them in a den where more cubs are born, in the spring the elders come out of the den and live on their own. This phenomenon is characteristic of our Caucasian bears of small morph.
Recently, the she-bears have been multiparous not only in our area but also in other regions of Russia. It is no longer uncommon to see four cubs - older ones, at the age of six months, not just those born in a den; however, not all cubs survive during the first six months.
In the Caucasus, according to estimates, each she-bear has on average 1.6 bear cubs, each one has one or two, or three bear cubs (which is rare). The bears of smaller morphs are also different here, they are more fertile, she-bears often have two or three cubs.
This also has an effect on the overall population level, it remains stable in our mountains, and in years when there is a lot of food, when winters and springs are warm, the number of bears even increases. If this trend continues for another 5-7 years, the number of bears in the Krasnodar Territory may grow to 800 individuals and more. Compared to other animals, the bears have not been sufficiently studied; they remain a big mystery that we will have to solve in the future.