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Brown bear © Jacques Ioset

Brown bear (Ursus arctos)

  • Appearance: Strong, stocky body with prominent shoulder hump, short tail. Large head with round ears, small eyes and a relatively long snout. Fur mostly brown, with darker legs and back.
  • Size: body length 140–200 cm, shoulder height 70–110 cm. Males larger than females.
  • Weight: Males 150–280 kg, females approx. 50% lighter.
  • Life expectancy: up to 21 years in the wild

Status and threats

Legal status:

Red List of Endangered species:

Despite its sporadic occurrence, the brown bear is still classified as Extinct in Switzerland, due to the lack of reproduction. However, even the Alpine population as a whole is threatened due to its small size and will not be viable in the long term in this form. There were 34 known mortalities in the Alpine population between 2003 and 2019. Almost half of them were caused by humans, i.e. traffic collisions, illegal killings or legal killings. The last category includes the two bears from Switzerland, that were classified as risk bears and consequently shot.

Spatial & social structure

Typical bear habitat. Slovenia, 2011. © Jacques Ioset

Brown bears are very adaptable. They use forests, steppes, craggy mountain areas or the Arctic tundra. Today’s bear populations are largely restricted to vast wooded areas, usually mountainous ones that are sparsely populated by humans. Food availability is crucial. Equally important is the possibility to avoid humans and hide from them. Additionally, inaccessible sites for hibernation pose a limitation on their landscape distribution. The slightest disturbance near the site can wake a bear, interrupt its hibernation and cause it to leave. This can be a severe event, especially for a female with cubs as she may abandon them.

Brown bears are solitary and use areas that vary largely in size depending on food availability. In Scandinavia males roam areas of up to 1,600 km², while in Croatia they use about 130 km². Females have smaller home ranges: in Scandinavia female brown bears are known to occupy up to 225 km² and in Croatia about 60 km². Unlike lynx and wolves, bears are not strictly territorial: they can tolerate same sex individuals within a home range. As their diet consists largely of vegetarian food, bears do not defend an exclusive hunting territory. With seasonally rich food availability bears may in fact temporarily live quite close together. Alaskan brown bears for example, congregate in relatively large numbers to fish during the salmon migrations.


Juvenile brown bears © Jacques Ioset

The mating season is between May and July. During this period males often fight. Males and females usually mate with several partners. The average litter consists of two cubs, which can be from different fathers. Embryonic development pauses shortly after fertilization and delayed implantation of the embryos takes place in late November/early December. The effective gestation period occurs during the hibernation period and lasts about two months. Birth takes place in January-February in the den. A litter is composed of 2 to 3 blind and grey-haired young that weigh only about 200 to 300 grams. The female, who does not eat at all during hibernation, nurses its young with highly nutritious milk and the cubs weigh already around 5 to 6 kg when they leave the den for the first time in April – May. The young then come out of the den and are already able to travel long distances with the mother, staying with her 1.5 to 2.5 years as they learn actively from her. Consequently, a female bear can give birth every two years at most.


The diet of the European brown bear varies throughout the year. When a bear leaves its den in spring, the digestive system must be slowly reactivated. Three-quarters of its nutritional requirements are filled by plants but carrion is also used. By the end of the summer it is indeed easy to imagine the origin of the expression “hungry as a bear” since these animals must accumulate huge fat reserves for winter. During the summer/fall season the food consists mainly of berries, fruits, nuts and honey. Insects are an important source of animal protein for the European brown bear. European bears may opportunistically hunt for prey and are known to kill unprotected livestock. In contrast, the North American subspecies regularly hunts and fishes throughout the summer season. Hibernation for bears is quite a phenomenon: they do not drink and eat for months, live fully on their fat reserves and produce no waste products (feces or urine). Physiological adaptation allows the urea to be recycled. Moreover, mothers give birth to their cubs during this time and nurse them with highly nutritious milk. During hibernation bears can lose up to 30% of their autumnal weight.

History in Switzerland

The last bear on Swiss territory was killed on 1st September 1904 in Val S-charl. It was a 116 kg female. © W. Rauch, Scuol

In prehistoric times the brown bear was present throughout the country. Around the year 1500 people began to heavily and continuously populate the central plateau resulting in widespread deforestation and therefore the disappearance of the brown bear from this area. The last bears in the northern Alps were killed between 1800 and 1850 and the Jura population also disappeared around this time. The species survived only in the Grisons and the Ticino Alps. With the invention of modern rifles, the number of bear kills soared once more and by the beginning of the 20th Century the species was only present in a small area of the Lower Engadine in southeastern Switzerland, and in the Val Müstair and Val dal Spöl regions. In 1904 the last bear was shot on Swiss territory. The last visual observation dates from 1923. Soon after the eradication of the brown bear, discussions began about enabling its return to Switzerland. Potentially suitable habitat exists in the Ticino and Grisons Alps. This region is connected to the richly forested alpine areas of northern Italy from which brown bears can migrate naturally. From 1999–2002, a reintroduction project was carried out in the Italian Trentino, only about 50 km away from the Swiss National Park. The success of this project had increased the probability of a natural re-immigration of brown bears into Switzerland. In July 2005, the first bear was seen in the Lower Engadine, after more than 100 years of absence. Since then, brown bears come over from Italy almost every year.

The back of a postcard (see figure) contains a detailed account of the meeting:

A postcard of probably the last bear observation within the Swiss National Park © Archives SNP, Zernez.

“It was early October 1904, when a double sentry at Punt Purif (Spöl) saw a large bear. It came west through the scree down Punt Purif and approached the guard to about 100 meters. The soldiers clearly saw the large head and the large paws. Also from its gait, they recognized the animal as a bear. One of the soldiers then gave off two warning shots, whereupon the bear ran away in giant leaps. When I heard about that story, I immediately went to Punt Purif and found the track it left in the soft ground of the forest on the left shore of the Spöl. Zernez, December 29, 1914 Lieut. Adank, Bat 92, 2nd Company – Member of the Swiss Association for Nature protection.” © Archives SNP Zernez

Humans and brown bear

Bears are shy and usually succeed in avoiding people by detecting them with their keen senses of smell and hearing. Direct encounters and attacks on humans are very rare. Bears become dangerous when they start regularly searching for food within settlements. Bears forage very opportunistically and are able to find suitable food in the vicinity of humans, if no counter-measures are taken, e.g. bear-secure waste systems.

The fondness of bears for honey is legendary; however, the looting of bee hives can nowadays be effectively prevented by installing electric fences. Bears may also prey on livestock with unprotected sheep being particularly vulnerable. If the herds are accompanied by a shepherd with dogs and penned at night the risk of a bear attack can nonetheless be minimized.

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