Domestic cats and their impacts on biodiversity: A blind spot in the application of nature conservation law

Abstract Free‐ranging domestic cats Felis catus , from owned pets to feral cats, impact biodiversity through predation, fear effects, competition, disease and hybridization. Scientific knowledge regarding these impacts has recently increased, making it timely to assess the role of nature conservation legislation in this connection. We do so with particular regard to the obligations of governments around the world under international wildlife law. First, we provide an overview of current knowledge, based on a literature review, concerning the ways in which domestic cats impact wildlife; the resulting effects on native species’ populations and ecosystems; and available strategies for addressing these issues. In light of this knowledge, using standard legal research methodology, we then identify and interpret relevant legal instruments, with a particular focus on international wildlife treaties. Lastly, we identify and assess factors that may influence the implementation of relevant obligations. The outcomes of this analysis indicate that numerous legal obligations of relevance to free‐ranging domestic cats already apply under global treaties such as the Convention on Biological Diversity, Convention on Migratory Species and World Heritage Convention, and a range of regional legal instruments for biodiversity conservation. Of particular significance are obligations concerning (a) invasive alien species; (b) protected areas and (c) protected species. Many national authorities around the world are currently required, under international law, to adopt and implement policies aimed at preventing, reducing or eliminating the biodiversity impacts of free‐ranging domestic cats, in particular by (a) removing feral and other unowned cats from the landscape to the greatest extent possible and (b) restricting the outdoor access of owned cats. Factors that can influence or impair the application of these obligations include considerations of feasibility, scientific uncertainty, the interests of cat owners and the (perceived) interests of domestic cats themselves. Even if such factors may to some extent explain why many authorities have hitherto failed to take effective action to address the threats posed by free‐ranging domestic cats, from a legal perspective these factors provide little ground for justifying non‐compliance with international wildlife law. A free Plain Language Summary can be found within the Supporting Information of this article.