Philosophiae Doctor (PhD) Thesis 2013:47 Department of Ecology and Natural Resource Management Norwegian University of Life Sciences • Universitetet for miljø- og biovitenskap Patterns and mechanisms behind the occurrence of bears close to human settlements Mønster og mekanismer bak forekomsten av bjørner nær bebyggelse Marcus Elfström Patterns and mechanisms behind the occurrence of bears close to human settlements Mønster og mekanismer bak forekomsten av bjørner nær bebyggelse Philosophiae Doctor (Ph.D.) Thesis Marcus Elfström Department of Ecology and Natural Resource Management Norwegian University of Life Sciences Ås 2013 Thesis number 2013:47 ISSN 1503-1667 ISBN 978-82-575-1147-0 PhD supervisors Professor Jon Swenson 1 – main supervisor Professor Ole Hofstad 1 Researcher Ole-Gunnar Støen 1 Associate Professor Andreas Zedrosser 2 1 Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences NO-1432 Ås, Norway 2 Faculty of Arts and Sciences, Department of Environmental and Health Studies, Telemark University College, NO-3800 Bø i Telemark, Norway PhD evaluation committee Associate Professor Nuria Selva Fernández Institute of Nature Conservation, Polish Academy of Sciences, Mickiewicza 33, PL-31-120 Krakow, Poland Senior Researcher Ilpo Kojola Finnish Game and Fisheries Research Institute, Oulu Game and Fisheries Research, Tutkijantie 2 E, FIN-90570 Oulu, Finland Committee administrator: Professor Stein Moe Department of Ecology and Natural Resource Management Norwegian University of Life Sciences NO-1432 Ås, Norway ii Table of contents Summary ...................................................................................................................................................... v Sammanfattning ....................................................................................................................................... vii List of papers ............................................................................................................................................. ix Introduction ................................................................................................................................................. 1 Objectives and their rationale .................................................................................................................. 4 Identifying which categories of bears approach settlements and are considered to be problem animals (Papers I, II, III) ..................................................................................................... 4 Explaining the likelihoods that different categories of bears occur near settlements (Paper I) ................................................................................................................................................... 5 Testing the paradigm of food search near people: diet and body condition in relation to settlements and problem bear status (Papers III, IV, V) ............................................................... 5 Materials and methods .............................................................................................................................. 6 Study area ............................................................................................................................................... 6 Study populations .................................................................................................................................. 6 Capture and handling of bears ............................................................................................................ 7 Data collection and analyses ............................................................................................................... 7 Summary of results .................................................................................................................................. 10 Identifying which categories of bears approach settlements and are considered to be problem animals (Papers I, II, III) ................................................................................................... 10 Explaining the likelihoods that different categories of bears occur near settlements (Paper I) ................................................................................................................................................. 14 Testing the paradigm of food search near people: diet and body condition in relation to settlements and problem bear status (Papers III, IV, V) ............................................................. 16 Discussion ................................................................................................................................................. 23 Identifying which categories of bears approach settlements and are considered to be problem animals .................................................................................................................................. 23 Explaining the likelihoods that different categories of bears occur near settlements ........... 23 Testing the paradigm of food search near people: diet and body condition in relation to settlements and problem bear status ................................................................................................ 26 Management implications ................................................................................................................. 28 Future research perspectives ............................................................................................................. 30 References ................................................................................................................................................. 31 Acknowledgements ................................................................................................................................. 45 Papers I - V have separate page numbers iii iv Summary Bears near settlements are considered to be a problem, because they may damage property and because people are afraid of them. The most accepted explanation for why some bears occur near settlements is that they associate people with easily accessible foods (i.e. food- conditioning). However, we found a similar composition and quality of the Scandinavian brown bears’ diet close to settlements compared to the same when in remote areas. Also, there was no correlation between the occurrence of problem brown bears and food conditions in either southern or northern Europe, and the body condition of problem and nonproblem bears was similar. These results give little support for food search or food shortage to explain the occurrence of problem brown bears near settlements in Europe. We found further that adult males denned farther from settlements and plowed roads than other categories of brown bears, that problem brown bears are younger than nonproblem bears, and that brown bears are generally younger in areas with higher human density in both southern and northern Europe. Females with young had a diet containing less protein and they showed a lower use of slaughter remains than other brown bear categories in south- central Sweden, supporting the hypothesis that the distribution of predation-vulnerable bears is affected to some degree by a despotic behavior of dominant bears. However, subadult bears showed no dietary deviance from adult males, suggesting no effects from interference competition. A literature review of brown bears, and American and Asiatic black bears revealed that subadults and females with cubs are overrepresented in areas near settlements in North America, Europe and Japan. This pattern likely occurs because bears are distributed despotically due to interference competition and/or avoidance of aggression or predation, and settlements may function as refuges for predation-vulnerable bears against dominant conspecifics. Thus, we suggested that habituation and food conditioning are proximate v responses, as a result of bears’ despotic distribution which is the ultimate mechanism. Attractant management is important, but failure to consider interactions among bears may lead to only treating the symptoms of habituation or conditioning. Bears seeking refuge near settlements may not be viewed as ‘unnatural’, but rather as an example of an adaptive behavior to avoid dominant conspecifics, which use habitats farther from people. vi Sammanfattning Björnar nära bebyggelse upplevs som problematiska därför att de kan orsaka skador och för att människor är rädda för dem. Den mest accepterade förklaringen till varför björnar uppehåller sig nära bebyggelse är att de har lärt sig att associera mänsklig aktivitet med lättillgänglig föda (en s.k. födobetingad respons). Men vi fann i Skandinavien en liknande sammansättning och näringsinnehåll i brunbjörnars diet nära bebyggelse jämfört med när samma björnar uppehöll sig i avlägsen terräng. Vi fann heller ingen korrelation mellan antalet problembjörnar och säsongsmässig födotillgång i varken södra eller norra Europa, och konditionsstatus var liknande mellan problembjörnar och övriga brunbjörnar. Dessa resultat indikerar andra bakomliggande orsaker än att problembjörnar primärt skulle söka föda nära bebyggelse eller uppleva en dålig födotillgång i avlägsen terräng. Vi kan konstatera att vuxna hanar vid övervintring placerar sina iden längre från bebyggelse och plogade vägar än andra kategorier av brunbjörnar, att problembjörnar är yngre än övriga brunbjörnar, och att brunbjörnar generellt är yngre