Predation by domestic cats in rural areas of central Poland: an assessment based on two methods

Studies of cat trophic behaviour can be based on collections of the prey brought home or the prey eaten by cats (i.e. analyses of scat/gut contents). Both methods involve biases with respect to palatability, prey size and assessment of hunting rates. Furthermore, these methods are often used on different groups of cats (i.e. house-based vs. feral), thus results are difficult to compare. In the present study, cats from the same area (rural areas in central Poland) were studied by both methods: prey brought home and prey eaten (scat and gut analyses). Both methods identified mammals as the most frequent prey (followed by birds). However, differences occurred in the percentages of the four main vertebrate groups brought home versus eaten by cats: reptiles tended to be brought home, whereas amphibians tended to be eaten. No such difference was found for birds and mammals. Second, the relative proportions of presumably more palatable and presumably less palatable prey differed. The relative proportions of mice and voles (the latter eaten more frequently) and the relative proportions of soricomorphs and rodents (the latter eaten more frequently) were different. Finally, small prey items (i.e. invertebrates) were recorded incompletely for the brought-home method. Overall, the prey-brought-home method underrepresented small prey and underestimated the predation rate for cats, whereas the prey-eaten method was less likely to record unpalatable prey. We thus recommend to combine these two methods to obtain fuller and truer assessment of cat predation.