Trait‐mediated thermal responses and multi‐axis spatiotemporal niche partitioning between coexisting top predators in ponds

Understanding how physiological constraints scale up to realized niche differences remains a central challenge in functional ecology. Temperature strongly influences metabolic performance, activity, and habitat selection in ectotherms, yet few field studies quantify how thermal responses interact with diel and habitat structure to shape predator coexistence in natural systems. Using year‐round trapping data, I quantified how eastern red‐spotted newts Notophthalmus viridescens and bluegill sunfish Lepomis macrochirus partition habitat across interacting axes of season, depth, time of day and temperature. Generalized linear mixed models revealed pronounced and opposing patterns of habitat use across interacting spatial and temporal axes. Newts were captured most frequently in deeper, cooler microhabitats during morning periods, whereas sunfish were captured most frequently in shallow, warmer habitats and afternoon periods. Harmonic models showed asynchronous seasonal trajectories, with newt activity peaking during cooler months and sunfish activity peaking during summer. Across the annual thermal gradient, newt capture rates declined with increasing temperature, whereas sunfish capture rates increased. Across combined season‐by‐depth‐by‐time states, overall niche overlap was significantly lower than expected under null models of random habitat use. These results indicate that differences in thermal sensitivity and behavioral thermoregulation can generate strong multi‐axis spatiotemporal segregation among ecologically similar predators, even in physically constrained systems. By linking thermal ecology to realized habitat use across diel and seasonal scales, this study demonstrates how trait‐mediated responses to environmental gradients structure predator functional roles and reduce interaction overlap in natural communities.