Adult males are on average 180 cm long and 85 cm tall, and weigh from 130 to 260 kg. Females are usually smaller in size and weight. The body mass of individual bears varies greatly throughout the year. Bears typically stay in dens over the winter to cope with winter food shortage. They can lose over 25% of their body weight while they stay in their den in winter.
Even though brown bear is classified as a carnivore species, they are actually omnivorous and mostly vegetarian in reality. They eat a wide variety of foods (e.g. fruits, berries, seeds, nuts, roots, grass, insects, carrion, sometimes wild ungulates). They typically collect food with the highest possible value available at a particular moment. Spring is its most challenging season, especially until the beginning of the growing season. During this time it may attack cloven-hoofed game which moves with difficulty due to late snow and ice. Carcase – bodies of animals that died during winter – also represents an important spring diet food source. Bears also feed on anthropogenic food (e.g. garbage, domestic animals, crops) when available and unprotected.
Brown bears start mating when 3 – 5 years old. Adult bears are solitary, except during the mating season (April to June). 1-4 (usually 2) cubs are born during the denning period (around January). At birth, the cubs are blind, toothless, hairless, and have less than 500 grams. They usually live with their mothers for 1.5 years. The social learning from the mother typically shapes the future behavior of the cubs.
Much like the majority of other large carnivores, bears have large home ranges and occur in low population densities. Females set up their home ranges next to their mothers’, while males disperse. Home ranges overlap. Bears are active during the day and at night. Their activity depends on environmental conditions, amount of food and human activity (Swenson et al., 2000).
Brown bears are generally shy and typically avoid people. They most likely retreat before we notice them, so it is therefore actually difficult to see a bear in their natural habitat. Central European bears do not see humans as potential prey. Bear attacks occur rarely and happen when they are surprised, provoked, or while defending their cubs.
Given they have a keen sense of smell, bears communicate through the rub trees where they leave their hairs and personal smell. A bears’ sense of smell is about 100 times better than a human’s, giving them a “sharp nose” for finding food over huge distances.
Between November and March, bears typically stay in their dens in order to conserve energy when food is scarce. A bear´s body temperature is lowered (drops to 2 °C) and both breathing and heart rates slow. They do not necessarily den in rock caves. They may also spend the winter under a fallen tree, in an open nest, under a cliff, or just hidden in dense vegetation. Spending winter in the den is probably an adjustment to lack of food during winter time and possibly to giving birth to cubs which are not capable of thermoregulation. But some bears may stay active all winter.
DID YOU KNOW?
Species of bears have at one or another time lived on all continents except Australia. Nowadays, there are 8 species of bears living on Earth and 6 of them listed as either endangered or vulnerable by IUCN. Brown bears are the most widely distributed bear species which appears in several different ecotypes all around the northern hemisphere. The largest brown bears are found in North America and NorthEast Asia and can weigh more than 700 kg.
Brown bears are the most widely distributed bear species which appears in several different ecological forms all around the northern hemisphere.