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Predator-Prey Interactions in an Individual Based Model Ditte Katrine Hendrichsen NERI / University of Copenhagen, Denmark Population Cycles in Small Rodents Ecological background The aim of this project Methods - ALMaSS Preliminary results Background Population cycles are known in a number of species The population cycles of small rodents in FennoScandia show a characteristic north-south gradient Several theories proposed to explain the cycles One these is the Specialist-Generalist Predation Hypothesis or the Predation Theory The Predation Theory The composition of predator species Primarily specialists in north Stoat (Mustela erminea) and Weasel (M. nivalis) Greater diversity of predators towards south including more generalist species Tawny Owl (Strix aluco) The Predation Theory The composition of predator species The presence of snow cover Landscape heterogeneity What Do I Want to Know? Can we generate cycles just by adding and changing predators? What are the effects in the prey dynamics when different scenarios are run? simulations with and without predators and different ratios of generalists and specialist predators simulations with different spatial characteristics Methods Model: ALMaSS Landscape model Animal model Model species: Field vole (Microtus agrestris) The Predator Elements in ALMaSS Death and reproduction rates Home range size, the size of the search area within the home range Efficiency How long they stay in a particular area and how far they move Preliminary Results I log(N+1) Standard scenario - No predators 4 3 2 1 0 1 21 41 61 81 Years voles Preliminary Results II log(N+1) Standard scenario - No predators 5 4 3 2 1 0 1 21 41 61 81 Years voles weasels Preliminary Results III Standard scenario - No predators 2 1 0 1 21 41 61 -1 -2 standardized voles weasels Preliminary Results IV Predators present No Predators N 10000 N 10000 8000 8000 6000 6000 4000 4000 2000 2000 0 0 1 21 41 61 81 Years 1 voles 21 41 61 81 Years voles ALMaSS in Theoretical Population Ecology Modelling may allow us to test scenarios which does not occur in nature Effects of weather Landscape structure and management Fauna composition ALMaSS in Theoretical Population Ecology Modelling may allow us to test scenarios which do not occur in nature ...and to run scenarios over several years, testing the long term influence of different parameters Acknowledgements Chris Topping Department of Landscape Ecology, National Environmental Research Institute, Denmark Mads Forchhammer Department of Population Ecology, Institute of Zoology, University of Copenhagen, Denmark