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The great migrations: conserving migratory ungulates in a transboundary contextorganized by Simon Thirgood (Macaulay Institute, Aberdeen) and E.J. Milner-Gulland (Imperial College, London)THE GREAT MIGRATIONS OF SERENGETI ANTHONY SINCLAIR, John Fryxell, Kristine Metzger, and Michael Norton-Griffiths, Centre for Biodiversity Research, Vancouver, BC, Canada (AS), Department of Integrative Biology, University of Guelph, Guelph, ON, Canada (JF), Centre for Biodiversity Research, University of British Columbia, Vancouver, BC, Canada (KM), Nairobi, Kenya (MNG) sinclair@zoology.ubc.ca Of 28 species of ungulates in Serengeti only four exhibit well-defined long-distance seasonal migrations. We compare migrating and non-migrating species. Migrations are correlated with abiotic factors (rainfall, alkalinity) and nutrition (protein, minerals). The function of migration is to access ephemeral food resources. The consequences of migration are (1) a higher population size, (2) escape from predator regulation, (3) indirect keystone effects on the rest of the ecosystem including soils, vegetation, competitors, and predators. These migrations determine the structure and function of the whole ecosystem. Access by migrants to critical resources is essential for conservation of the ecosystem. CAUSES AND CONSEQUENCES OF HERBIVORE MIGRATION: A THEORETICAL PERSPECTIVE JOHN FRYXELL, Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, jfryxell@uoguelph.ca Migration is recurrent ecological strategy in a broad range of taxa, including many ungulates. Nonetheless, the theoretical basis for migration has received only limited attention. Here, we use theoretical models to review the logical consistency of causal factors usually proposed to explain the evolution of ungulate migration: tracking ephemeral patches of resource abundance, tracking ephemeral patches of high resource quality, and/or avoidance of non-migratory predators. We show that resource abundance is an unlikely motivation for ungulate migration, because under normal conditions applying during the growing period, food abundance rarely constrains rates of energy gain. In contrast, resource quality is more commonly limiting. This is demonstrated by recent studies from Serengeti, suggesting strong links between resource quality and herbivore spatial patterns. Individualistic tracking of gradients in resource quality is unlikely to explain the observed patterns of ungulate migration, however, because such models produce minor seasonal migratory movement that is much less pronounced than that commonly observed. Directed movement in anticipation of encountering patches of high resource quality is capable of producing realistic migratory behavior, as is directed movement to reduce access by stationary predators. Both energetic and anti-predatory advantages should lead theoretically to increases in abundance of migratory ungulates, but the magnitude of the demographic effect due to anti-predator advantage is likely to be of considerably greater magnitude than that due to energetic benefit. THREATS TO THE GREAT MIGRATION: CONSERVING THE MIGRATORY WILDEBEEST OF THE SERENGETI Grant Hopcraft, Ephraim Mwangomo, and Simon Thirgood, Frankfurt Zoological Society, Arusha, Tanzania (GH), Tanzania National Parks, Arusha, Tanzania (EM), Macaulay Institute, Aberdeen, United Kingdom (ST), granthopcraft@fzs.org The 25,000 square km Serengeti-Mara Ecosystem (SME) in Tanzania and Kenya is the world’s largest intact savannah ecosystem with large-scale ungulate migration. Two million wildebeest, zebra, and gazelle migrate annually from the short-grass plains of the Serengeti to the woodlands of the Mara in a roughly circular journey of 400 km. The wildebeest are keystone species in the ecosystem and their cascading impacts on different trophic levels are profound. The Serengeti migratory wildebeest population is unusual in a global context in that its conservation status has improved over the past 50 years following its release from the pandemic rinderpest. Nonetheless, developments both within and outside the SME protected area network give cause for grave concern. In this presentation we use data from aerial census, GPS collar and monthly normalized difference vegetation index (NDVI) measures to assess variation in the migration routes of the wildebeest using minimum cost path analysis. Furthermore, we highlight two areas that pose threats to the migration, one to the west of the core protected area and one to the north, where agricultural intensification and illegal hunting are pressing problems. We also consider threats to SME posed by hydroelectric and water diversion schemes proposed in Kenya. These latter issues require transboundary cooperation and highlight the difficulities of managing migratory species. DECISION-MAKING IN A MIGRATORY UNGULATE: EFFECTS OF HUMAN INTERVENTION IN A DYNAMIC SYSTEM E.J. MILNER-GULLAND and Eric Morgan, Division of Biology, Imperial College London, Ascot, Berkshire, United Kingdom (EJMG), School of Biological Sciences, University of Bristol, Avon, United Kingdom (EM), e.j.milner-gulland@imperial.ac.uk The saiga’s reproductive strategy involves harem breeding and giving birth in large aggregations. Aggregation has costs through parasite and disease transmission and benefits through predator swamping, while temporal clumping is likely to be climatically-induced. Saiga ecology has been severely disrupted by human intervention. We have observed a collapse in population size, failure to conceive and to aggregate in birth areas, and changes in parasite loads caused by large-scale male-biassed poaching for meat and horns, disturbance in calving areas, and changes in numbers and movement of domestic livestock. Current conservation strategy in the region is based around designing Protected Area networks. We discuss the difficulties inherent in making policy-relevant predictions about saiga behavior and ecology from observations of a dynamic system that is currently at its nadir. How can we make meaningful predictions about saiga movement to inform Protected Area placement based on a critically disrupted system? We use the example of parasite transmission to demonstrate the utility of predictive modelling as a tool for understanding complex systems that are dynamic in space and time, and consider how to extend this approach to broader issues in saiga conservation. MIGRATION AND CONSERVATION OF THE MONGOLIAN GAZELLE TAKEHIKO ITO, Naoko Miura, Badamjav Lhagvasuren, Dulamtseren Enkhbileg, Seiki Takatsuki, Atsushi Tsunekawa, Zhaowen Jiang, Arid Land Research Center, Tottori University, Japan (TI, AT), PASCO Corporation Tokyo, Japan (NM), Institute of Biology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia (BL, DE), The University Museum, The University of Tokyo, Japan (ST), Yamanashi Institute of Environmental Sciences, Fujiyoshida, Yamanashi, Japan (ZJ), ito@alrc.tottori-u.ac.jp Conservation and management are urgently required for the Mongolian gazelle (Procapra gutturosa) inhabiting the Mongolian steppe. We captured and satellite-collared Mongolian gazelles, and examined the potential influence of the international railroad and international border fences on gazelle migration and whether their seasonal migration corresponded to shifts in normalized difference vegetation index (NDVI) in their habitat. The tracked gazelles never crossed the railroad and the border fences during the whole tracked period. It is likely that the railroad and border fences had a barrier effect on gazelle migration. The shift in NDVI values between summer and winter ranges corresponded with seasonal migrations of gazelles in southern Mongolia. In contrast, NDVI values were higher in the winter ranges than in both the summer and annual ranges throughout the year in central Mongolia. The results showed that NDVI is a good indicator of gazelle habitat, but NDVI alone cannot explain all seasonal migration of gazelles. It is important to evaluate the effectiveness and limitations of NDVI as an indicator of habitat quality. Our methods and results using satellite tracking and remote sensing have utility in studies and conservation on migration in ungulates. THE FACES OF A MIGRATION CORRIDOR—BEYOND PROTECTED AREAS AND THE CHALLENGE OF A CONFLICTED POPULACE JOEL BERGER, Steve Cain, and Kim Murray Berger, Wildlife Conservation Society, Teton Valley, ID, USA (JB, KMB), National Park Service, Grand Teton National Park, Moose WY, USA (SC), jberger@wcs.org The world’s long distance migrations are as a spectacular as they are threatened. For land mammals only a few persist and these are jeopardized by agriculture, inadequately-sized reserves, energy development, and a lack of political will to enable robust protection. Amongst the oldest known site-specific routes is the 6000 year old, 600 kilometer long migration of pronghorn from the Yellowstone Ecosystem (summer) to the Upper Green River (winter) sites in Wyoming. GPS data reveal three geographical bottlenecks narrowing to as little 120 meters in which all members of a population apparently pass. Efforts to conserve this restricted pathway, the longest for a terrestrial mammal between the Arctic and Tierra Del Fuego, concentrate on a 150 kilometer long (one-way) segment averaging less than 1.2 kilometers wide. These have yet to be successful although community meetings with diverse stakeholders reflect broad support. Obstacles to protect this narrow ribbon as a corridor in perpetuity fall within the human milieu and include squabbles about why migration needs to be sustained, how best to achieve it, if legislation is necessary, and whether bottom-up or top down forces are more likely to be successful. MIGRATORY DECLINES IN PARTIALLY MIGRATORY ELK POPULATIONS IN THE CANADIAN ROCKY MOUNTAINS: A RESULT OF TRANSBOUNDARY MANAGEMENT CONFLICT MARK HEBBLEWHITE and Evelyn Merrill, Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada, mark.hebblewhite@ualberta.ca Many populations of ungulates are partially migratory where only some animals migrate, yet few studies have addressed their conservation. Near Banff National Park (BNP), Canada, migratory elk have declined in the past decade. We investigated migratory declines in a transboundary population that wintered on provincial lands, but migrated inside BNP in summer. We hypothesized transboundary differences in predator and habitat management between agencies contributed to migratory declines. In a multi-scale analysis of elk resource selection we found migrants escaped predation and maximized forage quality, whereas residents exploited areas wolves avoided because humans harvested wolves. To evaluate how these differences translated to demography, we contrasted migrant and resident population growth rate via Leslie-matrix models. Because wolves avoided increased human activity outside BNP as a result of human-caused wolf mortality, predation risk for resident elk outside BNP was reduced. Moreover, prescribed fires inside BNP attracted elk to high predation risk areas. As a result, resident population growth rate was >1 with lower cause specific mortality from wolves, yet migrants were declining because of increased predation by wolves. Migrants were declining in part because predator and habitat management outside the park were not coordinated. Thus, our study demonstrates the need for increased interagency cooperation and management in conservation of migratory ungulates. THE LAST WILD REINDEER (RANGIFER TARANDUS TARANDUS) MIGRATIONS IN EUROPE OLAV STRAND and Erling Johan Solberg, Norwegian Institute for Nature Research, Trondheim, Norway, olav.strand@nina.no A large part of remnant European wild reindeer is found in the mountains of southern Norway. Archaeological findings and large pitfall systems suggest that both natural factors and human activities have led to the present distribution with 23 more or less isolated subpopulations. Population recruitment rates varies significantly between seven herds and differences in the density / recruitment relationships supports the hypothesis that fragmentation has imposed effects at the sub-population level through a uneven distribution of seasonal pastures. Because of the relatively large range size (approximately 8200 square km) and a east-west orientation of their living range, reindeer in Hardangervidda have maintained an extended nomadic behavior between geographically distinct summer, winter, and calving areas. In particular, the herd has high fidelity to its calving areas in the western parts of the mountain plateau. Knowledge of the scale of fragmentation in relation to habitat heterogeneity may therefore be important to understand potential effects of fragmentation on migratory species. Norwegian reindeer are managed by harvest at the scale of subpopulations whereas land management operates at the municipality and county levels resulting in complex responsibilities in land management and thus dangers of in future habitat loss. | |||||||||||||||||
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