Cats kill millions of vertebrates in Polish farmland annually

Abstract

We estimated the predation rate by free ranging domestic cats on vertebrates in rural areas of central Poland. We performed a door-to-door survey on the number of cats owned and type of food provided and combined results of the survey with the previous data on cats’ diet composition, estimated with different methods (prey-brought-home and prey-eaten). With the help of simulations, we estimated an average number of mammals and birds killed by cats on a single farm annually. 0.839 cats were kept in each farm, 78.5% of them were fed with leftovers. On average, cats from one farm brought home 16.4 mammals and 3.0 birds annually, but ate 198.9 mammals and 46.3 birds annually, although these two categories are not fully additive because cat can eat prey it brought home. Extrapolation of these figures to all Polish farmsteads (2.9 million in 2002) indicates that cats bring home and eat 48.1 and 583.4 millions of mammals, respectively, and 8.9 and 135.7 millions of birds, respectively. Our survey showed that cats in Polish farmland are kept as mousers rather than pets and little attention is paid to their welfare (i.e. are poorly fed). Thus, the total impact they impose on wildlife can be expected to be important.