Advances:
Based on empirical studies, trophic cascades have been documented for 7 of the 31 larg-est mammalian carnivores (not including pinnipeds). For each of these species (see figure), human actions have both caused declines and contributed to recovery, providing “natural experiments” for quantifying their effects on food-web and community structure. Large carnivores deliver economic and ecosystem services via direct and indirect pathways that help maintain mammal, avian, inverte-brate, and herpetofauna abundance or richness. Further, they affect other ecosystem processes and conditions, such as scavenger subsidies, disease dynamics, carbon storage, stream morphology, and crop production. The maintenance or recovery of ecologically effective densities of large carnivores is an important tool for maintaining the structure and function of diverse ecosystems.
Outlook:
Current ecological knowledge indicates that large carnivores are necessary for the main-tenance of biodiversity and ecosystem function. Human actions cannot fully replace the role of large carnivores. Additionally, the future of increasing human resource demands and changing climate will affect biodiversity and ecosystem resiliency. These facts, combined with the importance of resilient ecosystems, indicate that large carnivores and their habitats should be maintained and restored wher-ever possible. Preventing the extinction of these species and the loss of their irreplaceable ecological function and importance will require novel, bold, and deliberate actions. We propose a Global Large Carnivore Initiative to coordinate local, national, and international research, conservation, and policy