Across the globe, outdoor domestic cats – pets, strays, and feral cats – threaten wildlife in various ways. They do so through direct predation, fear effects, competition, disease, and hybridization. Scientific knowledge about these problems is rapidly improving, which raises the question: what do laws for nature conservation say about outdoor cats? We addressed this question, with an emphasis on international wildlife treaties.
First, we reviewed the ample literature on the ways in which, and extent to which, outdoor cats affect native species, from birds to bats to lizards; and on potential remedies. In light of this newly synthesized knowledge, we identified and interpreted relevant legal instruments. Lastly, we identified and explored factors that may influence the implementation of relevant legal obligations.
It turns out that many international treaties already apply to outdoor domestic cats. These include, for instance, the Convention on Biological Diversity, the Convention on Migratory Species, the World Heritage Convention, and various regional legal instruments. The most relevant specific obligations concern (a) invasive species, (b) protected areas, and (c) protected species.
Our analysis of these obligations shows that many governments around the world are currently required, under international law, to adopt and implement policies aimed at preventing, reducing or eliminating the biodiversity impacts of outdoor domestic cats, particularly by (i) removing feral and other unowned cats from the landscape to the greatest extent possible, and by (ii) restricting the outdoor access of owned cats.
It seems, however, that many governments do not yet comply with these obligations, and that cats are a blind spot in the application of international conservation law. Therefore, we also explored factors that may account for this blind spot. These factors include feasibility, scientific uncertainty, the interests of cat owners, and the interests of cats themselves. It might be that such factors can to some extent explain why many governments have failed to take effective action to tackle the cat problem (or even to call it a problem). However, our analysis demonstrates that, from a legal perspective, these factors provide little ground to justify continued non-compliance with legal obligations to protect wildlife from cats.