Effects of severe fires on the survival and body condition of Gracilinanus agilis in a Cerrado remnant

Foreseeing faunal responses to fire is a challenging issue, due to the context-dependent effects of fire. Although previous studies have registered declines in the abundance of vertebrates, particularly small mammals, following changes in fire regimes, the mechanisms driving these changes are still poorly understood. Hence, we investigated the effects of a severe fire on the abundance, survival, and body condition of a semelparous didelphid (Gracilinanus agilis) inhabiting one of the largest Cerrado remnants in the Triangulo Mineiro region. Using a before-after approach, G. agilis individuals were monitored from 2011 to 2016 through monthly live-trapping sessions. Gracilinanus agilis population followed repeated oscillations every year, with marked declines in abundance after the mating season, irrespective of the 2014 & PRIME;s fire. Although fire reduced population size, it did not lead to a precipitous decline in G. agilis abundance. Survival rates were not affected by fire; instead were determined by the sex and breeding status of individuals. The fire caused a decrease only in female body condition, which resulted in a reduced length of the breeding season and a lower number of juveniles following the disturbance. Our results support the contention that fire affects small mammals indirectly, mainly through its effects on recruitment. The observed weak fire effects on the population level seem to be associated with the less sensitive dynamics of fast-living species. Hence, we emphasize the need to investigate the mechanisms driving faunal responses to fire, especially considering the recent changes in fire regimes and the role of life histories on species responses.

Automated summary

This study investigated the effects of a severe fire on the abundance, survival, and body condition of Gracilinanus agilis. The results showed that fire had a minimal impact on population size but did affect female body condition and breeding season length, which in turn affected recruitment. The study suggests that fire primarily affects small mammals indirectly through its effects on reproduction.