付記する学位プログラム名: グローバル生存学大学院連携プログラム / 京都大学 / 0048 / 新制・課程博士 / 博士(地域研究) / 甲第20732号 / 地博第223号 / 新制||地||82(附属図書館) / 京都大学大学院アジア・アフリカ地域研究研究科東南アジア地域研究専攻 / (主査)教授 岩田 明久, 准教授 山越 言, 准教授 古澤 拓郎, 教授 神﨑 護 / 学位規則第4条第1項該当 / Doctor of Area Studies / Kyoto University / DGAM

Jordens biologiska mångfald minskar i en allt snabbare takt, men mitt i denna ekologiska katastrof börjar arter på vissa håll att återkomma. De stora rovdjuren i Europa är ett sådant exempel. Från att ha varit försvunna från stora delar av sina utbredningsområden är de flesta populationer numera stabila eller ökande. I Skandinavien har lodjurspopulationen expanderat och efter närmare 100 års reproduktiv frånvaro förekommer åter föryngringar i Sydsverige. I Östergötland finns i dagsläget ca 50–55 individer och mycket tyder på att stammen kommer att fortsätta öka. Genom att sammanställa och analysera data från inventeringsrapporter, observationsloggar och avskjutningsstatistik har jag undersökt lodjurspopulationens utveckling i Östergötland och beräknat länets bärkraft för lo. Beräkningen av bärkraften har utgått från klövviltförekomsten samt mängden lämpligt habitat. Resultaten visar att Östergötland har gott om lämpligt habitat och en hög bytesdensitet, som är jämförbar med flera lodjurstäta områden i Europa. Givet dessa förutsättningar har Östergötland en bärkraft för lo som ligger långt över dagens populationsnivå. Uppskattningsvis kan Östergötland hålla mellan 80–140 självständiga individer. Detta skulle innebära en fördubbling av dagens antal och kunna leda till såväl positiva som negativa konsekvenser för samhället. Lodjur kan innebära ett hot mot tamboskap, men de senaste årens rapportering visar att angreppen orsakade av lodjur är begränsade. Även påverkan på klövviltstammarna är i dagsläget försumbar. På sikt skulle dock en större lodjurspopulation kunna reglera klövviltet och på så vis minska mängden trafikolyckor och skador på skog. / Global biological diversity is declining at rates comparable to historic mass extinction events. Despite this, some species are returning to their former ranges, an example being the great carnivores in Europe. After being driven to the verge of extinction, most of today’s populations have recovered to a stable level. The Eurasian lynx (Lynx lynx) has re-expanded its range in Scandinavia and, after almost 100 years, is once again reproducing in southern Sweden. There are currently about 50-55 individuals in Östergötland county, and many factors implies that their number will continue to grow. By collecting and analysing data from different governmental reports and other sources I have tried to cover the development of Östergötland’s lynx population and to calculate the carrying capacity. The calculations are based on ungulate densities and amount of suitable habitat. The results of the study show that Östergötland contains a large amount of connected woodland habitat and high densities of prey, comparable to regions in Europe with high occurrence of lynx. Given these circumstances Östergötland has the capacity to support approximately 80-140 independent individuals. These numbers are twice as large as today’s population level and if reached could lead to positive as well as negative consequences for society. The lynx is a known threat to livestock but reports from recent years suggests that lynx attacks on sheep in Östergötland are limited. The effects of the current lynx population on ungulate demographics are also negligible. Although, these effects might increase with a larger lynx population, leading to lower rates of vehicle collisions and less damage in the forestry sector.

Cougars (Puma concolor) are a growing concern for managers of Pacific Rim National Park Reserve and Clayoquot Sound UNESCO Biosphere Reserve on the west coast of Vancouver Island, British Columbia. Since the mid-1990s, the frequency and intensity of human-cougar interactions have dramatically increased. Concurrently, these areas have become increasingly popular for human activities. The primary goal of my study was to recommend ways to reduce the potential risk of human-cougar interactions to ensure long-term conservation of cougars while minimizing risks to visitor safety. To achieve this goal, I examined the use of two noninvasive approaches. First, during 2005-2006, I compared the rate of detection, cost and time required for a detector dog, sign surveys, scented rub pads and remotely triggered cameras to detect cougars in coastal temperate rainforests. Sign surveys were the most effective method due to the availability of good tracking substrate throughout the study areas. Cameras were also practical because they could be used by less skilled personnel and had the capacity to detect several species of wildlife. Second, I demonstrated the utility of pre-existing data by analysing the spatiotemporal trends of human-cougar interactions on the West Coast Trail from 1993-2006. My results showed a moderate increase of reported human-cougar interactions (n = 157) despite a steady decline in hiker numbers across these years. I identified four areas where activities of people and cougars repeatedly overlapped (hotspots). In general, interaction locations were primarily associated with high human activity: near campsites and landscape characteristics that were associated with campsites (i.e., beaches and freshwater drainages >20 m wide). However, the distribution of hotspots suggests that the co-occurrence of human-use areas (e.g., campsites) and important travel routes (e.g., freshwater drainages and logging roads) used by cougars may increase the likelihood of interactions. These findings will allow protected area managers to proactively mitigate human-cougar conflict through visitor education and protocols that reduce people and cougars from intersecting in space and time.

Intraguild competition and predation have been recognised as important ecological factors influencing the population dynamics of carnivores. The effects of these interactions are often asymmetrical due to a size-related dominancy hierarchy. However, it has been suggested that competitively subordinate carnivores can minimise the costs of predation and competition through spatial and temporal avoidance. Here I investigate the ecological and behavioural mechanisms by which cheetahs (Acinonyx jubatus) coexist with competitively stronger lions (Panthera leo) and spotted hyaenas (Crocuta crocuta). Fieldwork was carried out in the Okavango Delta, northern Botswana, between October 2008 and August 2011. A total of 20 Global Positioning System (GPS) radio-collars were fitted on all known cheetahs (n=6), lion prides (n=5) and spotted hyaena clans (n=6) in the study area (approx. 3 000 km²). Pre-programmed radio-collars recorded locations and activity continuously for each individual and these data were complemented with direct behavioural observations. Cheetah data were analysed with respect to the temporal and spatial likelihood of encountering lions and spotted hyaenas. Results suggest that the response to the risks posed by other predators is species-specific, habitat-specific and dependent on the immediacy of the risk. Resource partitioning was not the main mechanism for coexistence as cheetahs overlapped extensively with lions and spotted hyaenas in time, space and habitat use. Instead, cheetahs adjusted their spatial distribution in response to immediate risks or adapted their habitat use depending on their vulnerability (e.g. behaviours such as feeding or with differing levels of moonlight at night). In general, cheetah temporal and spatial distribution is a hierarchal process, firstly driven by resource acquisition and thereafter fine-tuned by predator avoidance. In addition, habitat heterogeneity seemed to be key in facilitating coexistence. Understanding the behavioural mechanisms that interacting apex predators adopt to regulate these negative interactions could be crucial to carnivore conservation, especially as human-related habitat loss is forcing species into ever smaller areas.