Patch-mosaic burning is a widely accepted practical approach to managing biodiversity, whereby spatial and temporal diversity of fire is manipulated to benefit biotic diversity. We use simulation experiments based on stochastic population viability analysis to evaluate the implications of contrasting patch-mosaic burning scenarios for the population dynamics and risk of decline of four species of small mammals in northern Australia. Our results, based on models developed from detailed mark-recapture data, suggest that fire frequency has more influence on small-mammal persistence than fire extent. Risk of extinction increased for all four species when fire frequency exceeded once every five years. Under current ambient fire regimes most Australia tropical savannas burn more frequently and therefore seem to have unfavourable consequences for this faunal group and risk precipitating severe future declines.