Photo: Miha Krofel

About brown bears

The brown bear is an important element of nature and cultural heritage, not only in Slovenia but also elsewhere in Europe. Its numbers were severely reduced in a large part of Central and Southern Europe in the 19^th century, even extinct in some parts. Nowadays people’s attitude towards this large carnivore is shifting. There are projects in different parts of Europe that put immense effort in restoring the brown bear population: in the Austrian and Italian Alps, in the Pyrenees in France, in the Abruzzi Apennine, in Spanish Cantabria, in the Pindus Mountains and in the Rhodopes in Greece.

In the wider area of the Dinaric Mountains the brown bear was preserved because of the appropriate habitat – wide dense forests with rugged terrain and poor visibility and also because of the positive attitude of people living in that area towards the species. As the westernmost part of a dense Dinaric population Slovenian bears are important for natural re-colonization of the Alps. The living conditions in Slovenia to a great extent resemble conditions in areas where bears live in the Central and Southern Europe or where they could potentially be present. Therefore the Slovenian brown bear management strategy is also important for other European countries.

The brown bear is considered a vulnerable species due to its spatial demands, opportunistic feeding nature, great mobility and obvious tolerance for presence of people. It has been listed on a Red List of threatened species in Slovenia since 1993 and it is also protected by other international conventions such as the Bern Convention.

Protection and management of such a rare, endangered and charismatic species as the brown bear is not easy. When it comes to this magnificent carnivore the public opinion is normally divided and the public closely follows the managers’ every step. It is pivotal that managers who manage the bear population make decisions based on scientific facts which cannot be disputed. Taking into consideration scientific facts enables the managers to avoid any possible accusations later on. Therefore conservation genetics methods are becoming increasingly more significant as they enable us to collect information on the genetic condition of the population, dynamics and size of the population, sex structure, dispersion and geographical and the phylogenetic origin of specimens. Knowledge of all these aspects of the population enables better planning and management of the population.

Bear ecology

Bears are solitary animals. Relations between specimens are in principal based on mutual avoidance, except during mating season. 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).

The bear is an opportunistic omnivore. It typically collects food with the highest possible value available at a particular moment (Kryštufek, 2003). The majority of food is of plant origin. 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. From the time the growing season begins until late autumn they like to graze and eat fruits of forest trees and plants (cornel, hazel, strawberries, blueberries, brambles). In autumn, when they are accumulating fat for hibernation, forest trees (beechnut, acorn, chestnut, hazelnuts, walnuts) and fruit trees in orchards (pears, apples, plums) are important food sources. Bugs (ants, wasps, bees, wood beetles, chafers, weevil), their pupae and the previously mentioned carcase represent high-protein food sources for the bear (Krže, 1988). On occasion it hunts livestock, especially cattle. It also finds food at illegal waste dumps. When it finds food on people’s properties (small cattle, orchards, bee houses…) and causes damage, conflict with people arises.

The bear hibernates in winter; however, this is not deep winter hibernation as we know in for example dormice. Its body temperature only drops 2 °C. Its pulse and digestive system also slow down. Since it does not drink fluids during this period toxic waste starts accumulating, especially in urea. Nitrogen from the urea reincorporates into body proteins which are deposited in the lymph (blood-stained cerebrospinal fluid). The bear’s “winter hibernation” is actually a special form of starvation with the ability to neutralise toxic waste (Kryštufek, 2003). Some bears from southern European populations may be more active throughout the year. 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 (Swenson et al., 2000).

Bears are known for their long lifespan (the oldest recorded female bear in Slovenia is 21 years old (Jerina and Adamič, 2008)), late sexual maturity and extended reproductive cycle. It is a polygamous species. Mating takes place from mid-May to early July. After insemination embryos develop to the blastocyst stage. Further development is stopped until late November which is when implementation takes place. After that gestation takes another 6 to 8 weeks. In January or February females give birth in the den to 1 to 4 helpless cubs; they weigh approximately 0.5 kg. Cubs are considered grown from when they are 1.4 to 2.4 years old. In the Scandinavian population, which is the most intensely researched European population, they discovered that the female gives birth for the first time between ages 4 and 6. The interval between two gestation periods is relatively short, approximately 2.4 years (Swenson et al., 2000).

REFERENCES

• Jerina K., Adamič M. 2008. Analiza odvzetih rjavih medvedov iz narave v Sloveniji v obdobju 2003-2006, na podlagi starosti določene s pomočjo brušenja zob. Univerza v Ljubljani, Biotehniška fakulteta, Oddelek za gozdarstvo in obnovljive gozdne vire.
• Kryštufek B. 2003. Sesalci – Mammalia. V: Živalstvo Slovenije. Sket B., Gogala M., Kuštor V. (ur). Ljubljana, Tehniška založba Slovenije: 595 str.
• Krže B. 1988. V: Zveri II. Medvedi – Ursidae, psi – Canidae, mačke – Felidae. Kryštufek B., Brancelj A., Krže B., Čop J. (ur). Lovska zveza Slovenije, Ljubljana: 23-62
• Swenson J.E., Gerstl N., Dahle B., Zedrosser A. 2000. Action plan for the conservation of the brown bear (Ursus arctos) in Europe. Council of Europe, Strassburg, France.