Bears among people

Skuban, Michaela (2018): Bears among people: human influence on diet, daybed selection, habitat selection, and road crossing behaviour of the brown bear (Ursus arctos) in central Slovakia. Dissertation, LMU München: Fakultät für Biologie

Abstract

Bears living in a human-dominated landscape need to find a way to co-exist with people on a daily basis. People seriously alter their environment. Urbanization, agriculture, and road infrastructure actively change the natural environment of many wildlife species. Interestingly, especially omnivores and generalist species such as bears can even have a profit of habitat alternation mainly through adding of so-called “predictable anthropogenic food resources” (PAFS). These human-provided food resources are not only garbage or supplementary feeding stations, but also orchards or single fruit trees, agricultural crops, entrails left by hunters in the wood, and livestock animals. Bears can adapt to the availability of these foods and try to actively search for them. On the other hand in a human dominated landscape, animals are constantly disturbed by people. Many bears in cultural landscapes tend to be active during crepuscular or night-time hours in order to avoid people who are rather active during the day. Therefore, the relationship between Man and bear can be defined as ambivalent because the animals need to trade-off between feeding on PAFS and avoiding of human disturbance. Bears in Slovakia had never been extinct and increased their population numbers during the last decades. However, till I started this work, scientific research of bears was nearly absent. By the help of smaller project, it was possible to catch bears and mark them by GPS/GSM telemetry. For this study, I could use the data of 22 bears in three different mountain ranges. My main interests were 1) to find out how important human-provided food resources for bears in Slovakia are and if bears are really dependent on supplementary feeding stations during winter time. I found out that bears indeed feed year round on cereals, but that the majority of their energy budget is provided by natural food resources. However, maize fields are an important new and temporal habitat feature where some bears even stay for several consecutive day. Exceptional activity of bears during winter months was rather triggered by a combination of warmer temperatures, less snow and seed years of beech nuts than just the availability of high caloric food at supplementary feeding stations for ungulates. Second I wanted to know where bears can successfully retreat of human disturbance during the day and if the availability of PAFS can even influence the selection of a daybed. Most important driver for the selection of a daily resting site was the density of cover. Thus, bears selected for young regenerating forest, but also forest belts and thick shrubbery interspersed in agricultural land. This selection pattern was even more pronounced during late summer/autumn when bears need to fatten up for the upcoming winter and crops and fruits become available at the same time. Social structure (dispotic organization of the bear population) in bears as well as the reproductive status of females can significantly influence the choice of a daybed. Females with cubs of the year stay away from the other bear groups in order to minimize the risk of infanticide. These females and sub-dominant males can even approach human settlement in order to protect themselves or their offspring from dominant males. Further, habitat selection analysis showed that especially dominant males tend to monopolize attractive fields with maize. Sometimes, sub-dominant individuals even use people as a human shield. These results showed that non-protected areas could even need more protection because they are often very useful for wildlife including bears. Subsidies are paid for the reclamation of overgrown grazing areas which includes cutting of shrubs and small forest stands. Bears visible near villages are not necessary dangerous and often temporally restricted. Bear management should take this results more into account. However, people feel threatened if they have bears in close vicinity to their houses. Thus, education of people and working with public should be enhanced, too. Third, bears need to move among patches with attractive foods and quiet refuges during the day. In a human dominated landscape, roads intersect wildlife habitat and bears need to undertake risky road crossings. Analysis of road crossing activity of the bears in Slovakia showed that especially the amount of daily traffic can seriously limit or even inhibit bear movements. Even secondary roads with more than 5 000 vehicles/24hrs can act as a habitat barrier. Further, analysis if road mortality pointed out that majority of killed bears are young males which are the dispersing element of the population and enhance genetic exchange among sub-populations. A scientifically based analysis of bear movement routes can help to define places where mitigation measures would be really useful. Slovakia is still in process to enhance their road infrastructure. So far, Slovakia has still prospective possibilities to influence road planning processes in order to keep the landscape permeable for bears and other wildlife. Studies on movement routes should be intensified in order to avoid irreversible habitat fragmentation and disruption of bear subpopulations.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Keywords: brown bear, Ursus arctos, bear diet, daily resting place, GPS telemetry, habitat selection, anthropogenic foods, maize, human disturbance, road crossing behaviour, traffic induced mortality, Slovakia
• Themengebiete: 500 Naturwissenschaften und Mathematik ; 500 Naturwissenschaften und Mathematik > 570 Biowissenschaften, Biologie
• Fakultäten: Fakultät für Biologie
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 3. Mai 2018
• 1. Bericht­erstatter:in: Starck, J. Matthias