A full-grown brown bear can weigh up to 300 kilograms — roughly as heavy as three large motorcycles. Despite their size, they are remarkably quiet and agile in the forest. They can climb trees when young, swim across wide rivers, and run at speeds of up to 50 kilometres per hour in a short burst — faster than most humans on a bicycle.
Brown bears eat an enormous amount of food in autumn — up to 20,000 calories a day, roughly ten times what an adult human eats — to build up thick layers of fat before winter. Then they find a cosy den, usually under the roots of a fallen tree or in a rocky cave, and spend most of the winter in a deep sleep called hibernation.
In Bosnia and Herzegovina, bears mostly live in the Dinaric Alps, inside national parks such as Sutjeska. They are shy animals and usually avoid people completely. Foresters sometimes spot their huge footprints, scratch marks on tree bark (where they sharpen their claws), and the remains of berries and honey they have been eating.
Bear cubs are tiny when they are born — about the size of a hamster — even though their mother is enormous. The cubs stay with their mother for about two years, learning which plants are good to eat and how to find a safe den for winter.