Models simulating the predatory pressure of domestic cats
Development and credibility testing of individual-based models, simulating the predatory pressure of the domestic cats (Felis catus)
Department of Bioscience, Aarhus University, Aarhus, Denmark
M.Sc. Thesis January 2012
Master’s Thesis in Biology Manuscript draft aimed for publication in Ecological Modelling
Even though the domestic cat (Felis catus) is an abundant predator in many parts of the world, little is still known about the actual impact that domestic cats have on prey species. Studies have shown a great variation in the expected impact on prey species, and this variation can to a high degree be explained by spatial variations, as the local distribution and densities of both cat and prey have a markedly affect on cats predatory pressure.
This study has incorporated the spatial complexity of the domestic cats hunting pressure, by developing and testing three individual--based domestic cat predation models, with increasing complexity. The purpose was to evaluate both the need for complexity and the usability of the best model in reliably assessing the predatory pressure of domestic cats.
Development and testing was based on available literature data concerning important factors linked to cats predation pressure. Data for testing was primarily sourced from an urban and suburban study in Dunedin, NZ, which contained data of cats home range sizes in addition with estimates of the city--wide catches and the proportion of cats contributing to the catch numbers.
The results showed an improved ability to recreate the Dunedin scenario with added complexity to model behaviour, although it was not possible for any of the model types to decrease the deviation between the model output and the Dunedin observations, to a reasonable extent. The difficulties in improving the models compared to the test scenario, is very likely to be a result of inaccuracy in the key assumptions for the model simulations. The developed model does, however, still provide a useful purpose, as it can offer rough evaluations of cats hunting pressure. Moreover, it is spatially flexible and, as opposed to conventional extrapolation methods, can be applied in a wide range of possible scenario types. Reliable and testable data of domestic cats hunting pressure is, however, needed before a more accurate evaluation of an individual-based cat predation model can be attempted.
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Yolanda van Heezik, thanked and cited in the above thesis, has written various journal-published articles about feral freeroaming cats and was a contributor to The Wildlife Society's propaganda package on cats in the spring 2011 issue of Wildlife Professional that I shared with leading cat advocates on March 12, 2011.