Trade-offs between effectiveness, selectivity and animal welfare in invasive mammal control in Europe: A systematic review

Biological invasions are a major driver of global biodiversity loss, increasing the need for effective control of invasive vertebrates across Europe. However, management methods vary in effectiveness, selectivity, feasibility, animal welfare implications, and public acceptability. We systematically reviewed the scientific literature on population control methods for five invasive mammal species of concern in the European Union: raccoon, raccoon dog, muskrat, American mink and nutria. Following the PRISMA framework, two hundred forty-one experiments were evaluated according to management technique, control effectiveness, selectivity, animal welfare, and practical applicability. Live trapping was the most frequently used technique (80.2%), reflecting its broad applicability, although it was not consistently the most effective method. Evidence for hunting was limited to two studies reporting population reductions of 50% and 107%, respectively (the latter exceeding 100% due to immigration), and these estimates should therefore be interpreted cautiously. Fertility control was primarily applied in urban areas, where animal welfare and social considerations may outweigh rapid population reduction. Major evidence gaps concerned direct comparisons among techniques, long-term effectiveness, economic efficiency, and impacts on native biodiversity. No universally optimal control method emerged. Effective invasive vertebrate management therefore requires balancing ecological effectiveness, selectivity, animal welfare, economic constraints, habitat characteristics, and management objectives. The limited comparative evidence currently restricts identification of optimal management strategies. Standardised comparative and long-term studies are needed to strengthen evidence-based management and policy for invasive vertebrates across Europe.