Grazing among carnivores: Managing cattle depredation across the Western-world
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Large carnivores such as wolves and bears may prey on cattle. With the recent recovery of large carnivore populations in the Western world, cattle depredation is expected to increase. To mitigate potential conflicts, it is therefore important to find best practice for cattle grazing in carnivore-exposed areas. In my thesis I examined depredation rates of cattle by carnivores in different regions of Europe and North America and performed a survey and an interview study on cattle farming practices, losses to carnivores and other causes of mortality, and mitigation techniques to reduce depredation. My objectives were (1) to examine cattle depredation over time in carnivore-exposed areas across different countries; (2) to understand the possible geographical variation in cattle depredation in relation to carnivore species present, cattle and carnivore densities, grazing system and preventive measure(s) applied; and (3) subsequently, make recommendations. I hypothesised that predator density influences cattle depredation. Further, I hypothesised higher depredation rates for herds in extensive and free-ranging systems than in systems where cattle grazes in close vicinity to the farm. I expected to see differences between continents and areas both in depredation rates and commonness and effectiveness of measures applied, due to differences in habitat, farming practices, carnivore densities and carnivore management. Depredation statistics, cattle- and carnivore densities were collected from 25 areas in Europe and North America. The survey was carried out in 18 areas and the interview with eight of the survey participants. I mapped depredation trends over time and modelled depredation of cattle as a function of carnivore presence and density, year, and forest cover. To analyse the social data, I performed a descriptive and inferential analysis, using non-parametric tests. Cattle depredation increased over time in 70% of the areas in Europe and 60% of the study areas in North America. Cattle depredation was positively related to wolf density in Europe, but only weakly in North America. The social study results aligned with this finding and also showed that depredation occurred more often in extensive and free-grazing systems. Lastly, measures to prevent cattle depredation differed greatly between the continents. While electric fencing was most common in Europe, Americans used lethal control, avoidance and herding to a larger extent. In general, a higher number of preventive measures are commonly used in North America than in Europe. There is urgent need of a standardised, uniform method to monitor livestock depredation. Especially throughout Europe, where cattle depredation has increased the most and, according to the interviewees, the problem of cattle depredation has become more urgent. I wrote recommendations about: I) the carnivore species, II) replacement of electric fencing and avoiding carnivores, III) carnivores avoiding cattle, IV) lethal control of carnivores.