Middle-out ecology: small carnivores as sentinels of global change

Species that respond to ecosystem change in a timely, measurable, and interpretable way can be used as sentinels of global change. Contrary to a pervasive view, we suggest that, among Carnivora, small carnivores are more appropriate sentinels than large carnivores. This reasoning is built around six key points: that, compared to large carnivores, small carnivores 1) are more species-rich and diverse, providing more potential sentinels in many systems; 2) occupy a wider range of ecological niches, exhibiting a greater variety of sensitivities to change; 3) hold an intermediate trophic position that is more directly affected by changes at the producer, primary consumer, and tertiary consumer levels; 4) have shorter life spans and higher reproductive rates, exhibiting more rapid responses to change; 5) have smaller home ranges and are more abundant, making it easier to investigate fine-scale management interventions; 6) are easier to monitor, manage, and manipulate. Therefore, we advocate for incorporating a middle-out approach, in addition to the established top-down and bottom-up approaches, to assessing the responses of ecosystems to global change.

Automated summary

Small carnivores are more appropriate sentinels of global change than large carnivores due to their greater species diversity, wider range of ecological niches, more direct effect from changes at different trophic levels, faster response rates, easier management and monitoring.