Jaguar Density at the Northeastern Limit of Its Distribution in Mexico

Reliable estimates of population density are essential for the conservation of apex predators such as the jaguar (<i>Panthera onca</i>), particularly in peripheral regions of their distribution where existing data are insufficient to guide effective management. In Mexico, northeastern landscapes remain underrepresented in jaguar research, limiting the development of context-specific conservation strategies. To address this gap, we conducted a camera trap survey in the El Cielo-Sierra de Tamalave biological corridor, a transitional zone located at the northeasternmost limit of the species' range. Over a 91-day sampling period, we deployed 104 cameras across 52 paired stations and applied a random thinning spatial capture-recapture model (rt-SCR), which integrates both identified and unidentified photographic detections. This represents the first application of rt-SCR to jaguar data in Mexico. The model yielded a density estimate of 1.29 (0.93-1.70) individuals per 100 km², with adequate goodness-of-fit across multiple detection metrics. Despite low detection rates, the rt-SCR framework allowed for robust inference by maximizing data use and mitigates the loss of precision associated with excluding unidentified detections. Our findings provide a baseline for future monitoring in northeastern Mexico and demonstrate the utility of rt-SCR models in data-limited contexts. These results support the implementation of localized conservation actions and long-term monitoring programs in peripheral jaguar habitats, where population viability may depend on maintaining ecological continuity and minimizing anthropogenic pressures.