The brown bear is a mammal from the order Carnivora, the bear family (Ursidae), the genus Ursus and the species brown bear (Ursus arctos). The brown bear was once widespread throughout Eurasia and North America. In Europe, it has never lived only in Iceland and on the Mediterranean islands of Sardinia, Corsica and Cyprus.
Bears are the largest land carnivores. In the Balkans, adult females weigh an average of 100 kg and males 150 kg, but some specimens exceed 300 kg. During the year, the mass of the same adult can deviate by more than a third: the largest is in late autumn before the dening, and the smallest in early summer or at the end of the mating season. The body is covered with long hair and a thick undercoat. In summer, undercoat is much rarer than in winter. The color of the hair is mostly brown, and on the back it is often darker and even black. The tips of long hair can be light gray.
Bears meet about 95% of their nutritional needs with plant food, and the share of animal protein consists mainly of invertebrates and carcasses of larger animals. During spring and summer, herbaceous plants and grasses dominate, in summer various soft fruits join, and in autumn beech acorns as the main food for collecting winter stocks of subcutaneous fat. Due to the short and simple digestive tract, a significant portion of the plant food eaten passes through the entire tract poorly or not at all digested. This creates a need for the bear to take in as much food as possible. On the other hand, due to only partial decomposition during digestion, bear droppings help the spread of plant species, transmitting their seeds over long distances.
The male bear mostly live alone, the females with the youngs. At the beginning of December, it retreats to pre-prepared dens (caves, cracks in the rock, larger cavities in the trees). In the den, the males are alone, as are the pregnant females. There they spend time until spring (April – May), dormant, with vital functions slowed down and reduced metabolism. Its body temperature is then lowered, its heart rate drops and its breathing becomes less frequent.
They reach full maturity in the 4th year of life. They mate in the period May-June. The females mate every other year. Fertilization is usually performed by the strongest male. He can fertilize more females. Pregnancy lasts 30-34 weeks. Young females give birth in the den. It gives birth to 1-3 bears that are very small, weighing about 500 grams, almost naked and blind. They see after a month, breast-feeding until winter, but after 2 months of age they take, more out of curiosity, food of plant origin. Due to the abundance of milk, they progress quickly and get soft hair. The mother watches over them constantly.Then it is very dangerous. They spend the first winter in the den with their mother and stay with her until May or June, ie until the mating season. Brown bear habitats are uninterrupted areas rich in diverse plant cover in which the availability of food, the possibility of hiding and the existence of a nesting area are the most important features. In order for these areas to meet all the living needs of bears, they must consist of different types of forests, with the crucial role being played by the stands of large-leaved seeds such as beech, chestnut, oak, etc. In addition, the ability to move in all directions is important for bears, including zones with different altitudes, while for the survival of young in dens during the winter, peace in the habitat is necessary.
The grey wolf (Canis lupus) is a carnivorous and highly mobile species with a holarctic distribution, encompassing different habitat types, from tundra and taiga in the north to the deserts in the south, which can be explained by the species’ great ecological flexibility.
The persecution was especially intense in Western and Central Europe. In southern and eastern Europe, the hunting pressure on the wolf was significantly lower, so the wolf survived in a much wider area, primarily the Carpathians, the Dinarides and the Balkan Mountains. The extinction of the wolf in most of its historical area has left significant consequences on the structure and functioning of ecosystems previously inhabited by the species.
The gray wolf looks like a bigger dog. The average weight of an adult wolf is about 30 kg, while the largest specimens can weigh up to 50 kg. Females are generally lighter and smaller than males. Wolf fur consists of long covering hairs and a very thick undercoat. The hair is especially long on the neck where it forms the so-called mane. Wolves are fur-adapted to their habitat; thus in the far north they have pale gray to white fur color, in the forest – brown, darker color and sharp hair, and reddish color and short hair in steppes and deserts (Poklar, 2013). There is white hair around the lips, which gives the impression that the wolf has a smile.
The wolf pack is hierarchically organized. The parent pair of wolves is dominant, while the other members of the pack build relationships of superiority and subordination with each other. The dominant male wolf or female wolf decides when the pack will go hunting, where there will be a den, and the prey is eaten according to a hierarchy, the lower ranked after the higher ranked. Only one wolf (dominant) in a pack can have youngs, which is one of the mechanisms of self-regulation of the size of the wolf population, and prevention of inbreeding. It can be said that the leadership of the pack at the time of mating is taken over by the female wolf because she decides where to give birth, which means that it depends on her decision on which area the pack will live and hunt while the puppies are still too small to follow the pack.
The members of the pack communicate with each other by howling what makes gathering much easier. It is also one of the ways to mark the territory. They usually howl immediately after the hunt to gather. During the mating season, the reproductive members of the pack strengthen their dominant status in the pack by howling. Wolves howl more often in summer than in winter, because then young wolves learn new skills. They howl mostly at night, and in late spring and early summer they avoid howling so as not to reveal the location of the den where the cubs are. When hungry or hunting, wolves do not howl as they would reveal their presence to potential prey.
Mating of wolves begins in December and lasts until February. Pregnancy lasts 62 – 64 days. In March or April, wolves give birth to 3-4 blind cubs. They can see after 2 weeks. They are breastfeeding for 6 weeks, after which their parents feed them with partly-digested meat. After 3 months, the young come out in front of the lair and their parents bring them food.