Roaming domestic cats are among the top threats to global biodiversity and have contributed to the extinction of 40 bird species in the wild since 1500 (Doherty et al. 2016). In the United States and Canada, an estimated 2.4 billion and 200 million birds are killed by cats every year, respectively, and cat predation is the top source of direct, anthropogenic mortality to birds in these countries (State of the Birds 2014; Blancher 2013; Loss et al. 2013; Loss et al. 2015). 

Roaming domestic cats also contribute to indirect impacts on birds, such as competition, fear, and disease transmission (e.g., Bonnington et al. 2013). One of these diseases, toxoplasmosis, is caused by infection with the parasite Toxoplasma gondii. This parasite relies on felines to sexually reproduce and is subsequently excreted into the environment in the form of oocysts, which may then infect any warm-blooded species. This parasite’s persistence in and movement through the environment, lack of host specificity, and capacity for lethal and sub-lethal impacts make it a One Health and conservation threat, including for threatened birds (Miller et al. 2002; Work et al. 2016; Aguirre et al. 2019).