1. Predator-Prey Interactions in an Individual Based Model Ditte Katrine Hendrichsen NERI / University of Copenhagen, Denmark

2. Population Cycles in Small Rodents F Ecological background F The aim of this project F Methods - ALMaSS F Preliminary results

3. Background F Population cycles are known in a number of species F The population cycles of small rodents in Fenno- Scandia show a characteristic north-south gradient F Several theories proposed to explain the cycles G One these is the Specialist-Generalist Predation Hypothesis or the Predation Theory

4. The Predation Theory F The composition of predator species G Primarily specialists in north l Stoat (Mustela erminea) and Weasel (M. nivalis) G Greater diversity of predators towards south including more generalist species l Tawny Owl (Strix aluco)

5. F The presence of snow cover F Landscape heterogeneity The Predation Theory F The composition of predator species

6. What Do I Want to Know? F Can we generate cycles just by adding and changing predators? F What are the effects in the prey dynamics when different scenarios are run? G simulations with and without predators and different ratios of generalists and specialist predators G simulations with different spatial characteristics

7. Methods F Model: ALMaSS G Landscape model G Animal model F Model species: Field vole (Microtus agrestris)

8. The Predator Elements in ALMaSS F Death and reproduction rates F Home range size, the size of the search area within the home range F Efficiency F How long they stay in a particular area and how far they move

9. Preliminary Results I

10. Preliminary Results II

11. Preliminary Results III

12. Preliminary Results IV

13. ALMaSS in Theoretical Population Ecology F Modelling may allow us to test scenarios which does not occur in nature G Effects of weather G Landscape structure and management G Fauna composition

14. ALMaSS in Theoretical Population Ecology F Modelling may allow us to test scenarios which do not occur in nature F...and to run scenarios over several years, testing the long term influence of different parameters

15. Acknowledgements F Chris Topping Department of Landscape Ecology, National Environmental Research Institute, Denmark F Mads Forchhammer Department of Population Ecology, Institute of Zoology, University of Copenhagen, Denmark