Temperature-driven density gradients of two congeneric felids reveal contrasting responses to climate change at a range margin

Climate change causes divergent range shifts in cold versus warm-tolerant
species, potentially reshuffling biotic interactions at range margins.
Yet, outside of coarse distributional metrics, little information exists
regarding the ecology of species along range peripheries. Here, we use
camera traps and spatially-explicit capture-recapture (secr) modeling to
examine how climatic gradients influence current and future patterns of
density, abundance, and density overlap between two congeneric felids -
cold-adapted Canada lynx (Lynx canadensis) and warm-adapted bobcats (Lynx
rufus) - at a range margin in Washington, United States. Temperature drove
density patterns along the range margin, with lynx densities declining and
bobcat densities increasing as a function of temperature. Future
abundances, obtained via projection of current-day models onto future
climate scenarios, declined for lynx but were stable for bobcats, with
both species experiencing upward elevational shifts. Areas of the
landscape with high-lynx and low-bobcat densities declined in the future,
but areas with low-lynx and high-bobcat densities increased, with only
limited high-elevation refugia for lynx from expanding bobcat populations.
Our approach reveals how temperature gradients shape density patterns of
cold and warm-tolerant mammals and could be applied to other species and
montane systems to better understand mammalian population trajectories and
spatial associations at range edges.