Burned habitats facilitate predation and lead to long-term reductions in prey success

Intensifying wildfire regimes under global change are expected to shift species interactions through changes in habitat structure and composition, vegetation productivity, and sensory cues. Yet there is little evidence of how burn-induced changes in habitat composition and structure modify predator-prey relationships. We investigated how wildfires influence relationships between mule deer (Odocoileus hemionus) and cougars (Puma concolor) in the US Intermountain West using high-resolution telemetry data, kill site locations, and annual measures of mule deer fawn production. Burned habitats experienced a wide range of fire severities, and most fires occurred between 5 and 20 years prior to animal data collection. We found that cougars were located closer to deer and their kill sites were nearly 2× more likely to occur in burned areas compared to unburned sites, suggesting that burns confer advantages to predators. In addition, fawn production declined by up to 14% at sites with histories of more recent, higher severity burns. Our findings suggest that increasingly frequent, severe burns are diminishing herbivore reproductive success, potentially due to increasing predation risks that outweigh improved foraging opportunities for prey. Ultimately, we reveal a possible pathway through which changing fire regimes could threaten herbivore prey populations in Western US ecosystems.