What drives animal responses to high severity fire? The role of functional traits

Fire regimes are changing worldwide, with increases in the frequency, extent, and severity of fires posing growing risks to biodiversity. Fire severity - the degree of habitat alteration following fire - strongly influences both immediate survival and long-term recovery of fauna. Yet species' responses to severe fire are highly variable, shaped by traits, time since fire, and ecosystem context. We conducted a global systematic review of studies quantifying terrestrial vertebrate responses across fire-severity gradients. Using ordinal logistic regression, we assessed the predictive value of functional traits, time since fire, taxonomy, and ecosystem type for species' abundance and occurrence after fire. Across all severity comparisons, most species showed neutral responses; however, high severity fires elicited both more negative and more positive responses than low severity fires. Species with weak shelter, canopy-foraging habits, and preferences for closed canopies were more likely to decline after high severity fire. Negative responses diminished with increasing time since fire, highlighting opportunities for population recovery. Our findings identify functional traits that confer vulnerability to severe fire and provide a basis for predicting species' responses in unstudied taxa or regions. Targeted management, particularly within the first few years post-fire, will be critical to safeguard susceptible species as high severity fires become more frequent.