Living in the Pyrocene: Assemblage-Wide Terrestrial Vertebrate Responses to Mega-Fires in the Pantanal Wetlands

Fire is a natural evolutionary force that shapes ecosystems and population dynamics. However, recent increases in the frequency and severity of anthropogenic fires have had catastrophic impacts on biodiversity, even in fire-prone environments. In Brazil's Pantanal Wetland biome, 3.9 million hectares were affected by fires in 2020, leading to the mortality of an estimated 17 million vertebrates. In the Serra do Amolar region, 61.2% of the extent of eight protected areas was burned. Here, we use multi-year camera-trapping sampling between 2019 and 2022 at 50 sites and hierarchical Bayesian models to investigate terrestrial vertebrate responses to wildfires across 35 species within the Pantanal's Serra do Amolar region. We did not find evidence of effects of wildfires on occupancy. Nonetheless, five mammal (capybara, ocelot, red brocket deer, jaguar, and lowland tapir), two bird (bare-faced curassow and rufescent tiger-heron), and two reptile species (common green iguana and tegu lizard) showed a positive association between their occurrence probability and forest cover, indicating their vulnerability under future scenarios of recurrent wildfires. Additionally, the vertebrate species composition differed over the study period. In 2022, four species (undulated tinamou, jaguarundi, crab-eating raccoon, and Brazilian squirrel) were no longer detected. Among all species considered, 64% exhibited declines in relative abundance over time, with giant otters experiencing the most significant decline, while 36% showed increases. These findings raise significant concerns for wildlife conservation in the region, underscoring the need for long-term monitoring and proactive management strategies to mitigate the impacts of recurring wildfires on species abundance. We also highlight the importance of Serra do Amolar as a potential wildlife refuge, considering species resilience to a novel fire regime.