Literature review data and code associated with "An updated estimate of the number of birds killed by outdoor cats in Canada" published in Avian Conservation and Ecology

Supplementary literature review data for the paper "An updated estimate of the number of birds killed by outdoor cats in Canada" published in Avian Conservation and Ecology. Code to reproduce paper's results and figures included.Domestic cats, Felis catus, can be found almost everywhere in the world and estimating their impact on wildlife, including birds, requires the most up-to-date information. There are an estimated 9.3 million pet cats in Canada, 30 – 60% of which are given unrestricted access to the outdoors. Using the best available data at the time, Blancher (2013) estimated that cats kill between 105 – 348 million birds per year in Canada, making them the leading measurable cause of bird mortality in the country. However, a decade later, research on outdoor cats and their predation of birds has increased considerably, providing an opportunity to revisit this mortality estimate. Using recent data on predation rates and cat abundance, we estimated that cats kill between 19 – 197 million birds per year in Canada, 71% lower than Blancher’s (2013) earlier estimate. This does not mean that cat populations or predation rates on birds have declined since the previous estimate. Rather, we suggest that the difference can be primarily attributed to lower outdoor cat abundance estimated from field surveys compared to previously used cat ownership surveys and media reports of shelter intake data. While the estimated number of birds killed annually by cats is considerably lower than the previous estimate, outdoor cats remain a serious concern for native bird populations.