No abstract

Mega-fires in the Australian summer of 2019-20 resulted in the largest ever documented forest fire extent. These fires impacted many species, but individual responses remain poorly known, making assessments of their conservation status and ongoing threats uncertain. We assessed the influence of the 2019-20 mega-fires on habitat occupancy in the golden-tipped bat Phoniscus papuensis, a specialist which roosts in suspended birds' nests and occurs in relictual Gondwanan rainforest not typically exposed to fire. We used trapping and accounted for nightly detection probability (lower detection with increasing rainfall) to estimate site occupancy. Occupancy increased with the local (1 km buffer surrounding each site) extent of rainforest, gullies and unburnt forest. The model predicted a strong negative effect of fire in the surrounding buffer, with occupancy reduced from >90% at sites with suitable habitat (extensive rainforest and gully systems) surrounded by unburnt forest to 20% when the entire surrounding area was burnt (regardless of severity). Gully rainforest sites surrounded by a mixture of burnt and unburnt forest were modelled to have intermediate occupancy values. On average, fire severity mapping revealed that 22% of rainforest in the 1 km buffer surrounding our burnt sites was unburnt, 61% had a low severity burn, while 17% experienced a high severity burn. The lower occupancy of P. papuensis in burnt rainforest was associated with a reduction in the abundance of suspended bird nests, a critical resource used for day-roosting. Our results quantify the effects of extreme fire events on animal populations in rainforest that is normally unaffected by fire. The large extent of rainforest burnt during the 2019-20 Australian season of 'mega-fires' and its strong negative effect on occupancy highlights the vulnerability of animal species reliant on fire-sensitive habitat to a climate-change driven increase in such extreme fire events.

The 2019–2020 megafires in southeastern Australia extensively burnt forests including fire‐sensitive rainforests. Assessments of species' responses typically consider differences in occupancy or density between burnt and unburnt forest, but here we focus on how these fires influenced roost selection by a rainforest‐dependent bat. We radio‐tracked golden‐tipped bats Phoniscus papuensis in fire grounds to investigate whether roost location or type was influenced by fire severity one‐year post‐fire. Overall, we tracked 19 bats for a total of 117 roost‐days. Bats roosted (including maternity colonies) in the suspended nests of yellow‐throated scrub‐wrens and brown gerygone, typically in gully rainforest. No bats were captured, or roosts located, where fire severity was high. In the burnt portion of the northern study area, P. papuensis displayed a significant preference for roosting in unburnt rainforest compared to its availability along adjacent gullies. Patches of rainforest burnt by low–moderate severity fire were ranked as second preference. In the burnt portion of the southern study area, most roosts were in rainforest mapped as burnt by low–moderate fire severity, however, no selection was evident relative to availability of rainforest and mapped fire severity. Actual roost locations in the southern study area revealed that 62% were in small pockets of unburnt rainforest, with burnt areas nearby. We recorded early breeding and signs of a second litter in late summer, suggesting a post‐fire resource pulse in their prey (spiders). A higher than usual reproductive output may assist in recovery, along with the bat's mobility to aid finding remaining pockets of unburnt or low severity burnt rainforest with suitable bird nests for roosting. However, recolonization of rainforest burnt by high severity fire will first require recovery of structural complexity, microclimate and the recolonization of host bird‐built nests. We recommend ongoing monitoring to assess the recovery of this specialist bat.

The Australian summer of 2019/20 was impacted by megafires of a magnitude and severity never previously recorded. Whilst low severity fire has positive benefits for increased insectivorous bat activity and diversity, little information is available on the impact on rainforest specialised clutter dependant species such as the Golden-tipped Bat Phoniscus papuensis. Our aims were to assess the effects of fire on occupancy of habitat across the geographic range of P. papuensis in NSW, to determine the smaller scale effects of fire on use of diurnal roosts in rainforest through radio tracking and to trial the use of artificial structures to temporarily increase roost availability in burnt habitat. We observed that widespread fire encroaching on rainforest has a negative association with occupancy by P. papuensis, with this metric ~78% lower than in unburnt forest. In burnt areas, P. papuensis preferentially used unburnt refugia for their roosting sites in suspended bird nests and the loss of these habitat structures likely contributes to the disappearance of P. papuensis from the landscape. Artificial roosts were not used in the short-term (< 2 years post fire) and do not appear to be a feasible management tool. With the increasing frequency and extent of wildfires the most important factor for P. papuensis to persist in the landscape into the future is the protection of its habitat through ensuring sensitive management of large tracts of connected rainforest to help buffer against the encroachment of future mega-fires.