Forest avifauna exhibit enduring responses to historical high-severity wildfires

Forest fire size, frequency and severity are increasing worldwide, with corresponding reductions in long-unburnt habitat and greater modification of forest structure over wider areas. Understanding the implications for animals is imperative in optimizing management for species persistence and overall biodiversity. We investigated how avian responses to historical high-severity fire differ in forests at short (five years) and mid-range (16 years) time since fire, including whether increased time since fire mitigates any negative responses to high-severity fire. Sites were established in fire-prone dry forests of the Greater Blue Mountains World Heritage Area, Australia. A Bayesian latent variable analysis of bird data obtained from acoustic recordings was used to estimate the occurrence of 74 species in relation to time since fire (short, mid-range), the spatial extent of historical high-severity fire (limited, extensive), and their interaction. Time since fire influenced the number of species present, but only where high-severity fire had been extensive. Here, the lowest and highest number of species in the study occurred where time since fire was short and mid-range, respectively. At least ten species responded either positively or negatively to high-severity fire, but for nine of these species the response did not change with time since fire, potentially implicating persistent effects of such fires on habitat. Six other species were unlikely to occur at short time since fire, requiring habitat at mid-range time since fire. This finding suggests that these species would benefit from strategic retention of forest with longer fire-ages under increased fire activity asso-ciated with climate change.

Automated summary

The study demonstrates that the impact of high-severity fires on birds varies with time, with short-term fires having a more significant effect on species diversity, while mid-range fires can mitigate this impact to some extent.