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

Abstract

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

Support for the size‐mediated sensitivity hypothesis within a diverse carnivore community

“…Indeed, recent studies on spotted skunks have shown their utility in advancing our understanding of disease outbreaks (Harris et al, 2021), historical climate and land use change (Cheeseman et al, 2021a(Cheeseman et al, , 2021b, changing predator community dynamics (Bolas et al, 2022), and food web linkages between aquatic, terrestrial and arboreal systems (Tosa et al, 2023). Such sensitivities by small carnivores are not unique to our system and are likely represented in small carnivores in ecosystems globally (Do Linh San et al, 2022;Marneweck, Allen, et al, 2022). Further, as highlighted in this study, efforts to develop novel monitoring strategies for small carnivores have provided data and unique insight into the full suite of carnivores within communities.…”

“…Large apex carnivores can have well‐documented impacts on the abundance and behaviour of large herbivore prey, which have been shown to have cascading impacts on lower trophic levels and broader ecological processes (Ripple et al, 2014). While less popularized, small or medium‐sized carnivores (<16 kg) that typically occupy lower trophic levels within carnivore communities, account for 89% of all terrestrial carnivore species and can impact ecosystems in a variety of ways—ranging from predation of herbivores to seed dispersal (Do Linh San et al, 2022; Marneweck, Allen, et al, 2022). The ecological niches occupied by carnivores can change based on the presence of other carnivores, and alter their behaviour and abundance (and thus ecological impact) depending on the presence or absence of larger carnivores in a system (Linnell & Strand, 2000).…”

“…In other cases, small or medium‐sized carnivores are expanding their range, having negative impacts on ecosystem structure and function (Prugh et al, 2009). These apparent sensitivities have led to the hypothesis that there is size‐mediated sensitivity to environmental conditions, where the smallest carnivore in a system is likely to be the most responsive to the diverse suite of environmental and anthropogenic changes ecological communities are currently being subject to (Marneweck, Allen, et al, 2022). Combined with the ecological significance of small and medium‐sized carnivores, there is a need to better understand carnivore community dynamics to guide management interventions.…”

“…Our objective was to evaluate the relative support of each of the four primary hypothesized drivers (interspecific competition/predation, habitat complexity, food availability and anthropogenic disturbance) on the occurrence of carnivores within western North Carolina. We specifically took a middle‐out approach to our investigation, where we aimed to test the size‐mediated sensitivity hypothesis that smaller‐sized carnivores in our system would be most sensitive to inter‐specific competition and environmental conditions relative to larger carnivores (Marneweck, Allen, et al, 2022). Accordingly, we designed our study to maximize our ability to monitor small and medium‐sized carnivores, while also considering larger carnivores and small herbivore or granivore prey within our study system.…”

Fine-Scale Interactions between Leopard Cats and Their Potential Prey with Contrasting Diel Activities in a Livestock-Dominated Nature Reserve

“…The leopard cat, Prionailurus bengalensis from Family Felidae, is a typically nocturnal mesopredator in many temperate and (sub-)tropical forest ecosystems across most parts of Asia [ 19 ]. This cat can serve as an indicator species to prioritize conservation planning [ 20 ], due to the continued population decline as a result of habitat loss and illegal hunting [ 21 , 22 ]. This cat often uses opportunistic feeding strategies and exhibits plasticity in its habitat use and temporal activity to accommodate to habitat modification.…”