The magnitude of bird mortality caused by cat predationДЄfter excluding studies that did not meet a priori inclusion criteria designed to increase the accuracy of our analysis, we developed probability distributions of predation rates on birds and mammals. This magnitude of mortality is far greater than previous estimates of cat predation on wildlife and may exceed all other sources of anthropogenic mortality of US birds and mammals. We estimate that free-ranging domestic cats kill 1.3вЂ“4.0 billion birds and 6.3вЂ“22.3 billion mammals annually, and that un-owned cats cause the majority of this mortality. We conducted a data-driven systematic review of studies that estimate predation rates of owned and un-owned cats, and estimated the magnitude of bird and mammal mortality caused by all cats across the contiguous United States (all states excluding Alaska and Hawaii). In addition, no large-scale mortality estimates exist for mammals, which form a substantial component of cat diets. Existing estimates of mortality from cat predation are speculative and not based on scientific data 13, 14, 15, 16 or, at best, are based on extrapolation of results from a single study 18. This magnitude would place cats among the top sources of anthropogenic bird mortality however, window and building collisions have been suggested to cause even greater mortality 15, 16, 17. Estimates of annual US bird mortality from predation by all cats, including both owned and un-owned cats, are in the hundreds of millions 13, 14 (we define un-owned cats to include farm/barn cats, strays that are fed by humans but not granted access to habitations, cats in subsidized colonies and cats that are completely feral). However, assessing the conservation importance of a mortality source requires identification of which species are being killed (for example, native versus non-native invasive species and rare versus common species) in addition to estimation of total numbers of fatalities. Projects to manage free-ranging cats, such as Trap-Neuter-Return (TNR) colonies, are potentially harmful to wildlife populations, but are implemented across the United States without widespread public knowledge, consideration of scientific evidence or the environmental review processes typically required for actions with harmful environmental consequences 11, 12.ДЄ major reason for the current non-scientific approach to management of free-ranging cats is that total mortality from cat predation is often argued to be negligible compared with other anthropogenic threats, such as collisions with man-made structures and habitat destruction. Despite these harmful effects, policies for management of free-ranging cat populations and regulation of pet ownership behaviours are dictated by animal welfare issues rather than ecological impacts 11. Mounting evidence from three continents indicates that cats can also locally reduce mainland bird and mammal populations 5, 6, 7 and cause a substantial proportion of total wildlife mortality 8, 9, 10. Free-ranging cats on islands have caused or contributed to 33 (14%) of the modern bird, mammal and reptile extinctions recorded by the International Union for Conservation of Nature (IUCN) Red List 4. Scientifically sound conservation and policy intervention is needed to reduce this impact.Дomestic cats ( Felis catus) are predators that humans have introduced globally 1, 2 and that have been listed among the 100 worst non-native invasive species in the world 3. Our findings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals. Un-owned cats, as opposed to owned pets, cause the majority of this mortality. We estimate that free-ranging domestic cats kill 1.3вЂ“4.0 billion birds and 6.3вЂ“22.3 billion mammals annually. Here we conduct a systematic review and quantitatively estimate mortality caused by cats in the United States. The magnitude of mortality they cause in mainland areas remains speculative, with large-scale estimates based on non-systematic analyses and little consideration of scientific data. Free-ranging domestic cats have been introduced globally and have contributed to multiple wildlife extinctions on islands.

Anthropogenic threats, such as collisions with man-made structures, vehicles, poisoning and predation by domestic pets, combine to kill billions of wildlife annually.

California native game birds