Estimated number of birds killed by domestic cats in Colombia

Abstract

Wildlife mortality caused by domestic cats is evident where free-roaming house cats are present in the tropical Andes region, a phenomenon for which there is a lack of scientific reports. Our goal is to present plausible range estimates of the potential avoidable number of birds killed by domestic cats in Colombia. We calculated estimates of the number of birds killed as the product of the number of cats, the proportion of cats with at least some outdoor access, the proportion of cats that hunt wildlife, the annual predation probability, and adjustments for estimates of total prey killed by cats. We extracted such data not only from public records, but also from a citizen science study, for which we circulated a questionnaire to examine cat owners’ attitudes toward the impact of domestic cats on wildlife during the 2020 and 2021 COVID-19 lockdowns in Colombia. We estimated that three to 12 million birds are killed annually by domestic cats in urban and suburban areas. In addition, we estimated that cats kill eight to 29 million vertebrate fauna in the Andes of Colombia. The total kill estimate provides a first figure on the magnitude of the impact of an anthropogenic cause of wildlife mortality for Colombia. These estimates would be more rigorous if the unowned or feral cat population size in Colombia was better known. Because most pet cats in Colombia roam outdoors without supervision and their population is growing, they pose an increasing threat to wildlife. Intervention is urgent to mitigate bird mortality by domestic cats.