Drysdalia rhodogaster persists after wildfires 775
forest species fire severity appears to be an important factor, with the effects of fire being greatest in areas burnt at high severity (Law et al., 2022a,b; Letnic et al., 2023). Our occu- pancy models support emerging insights suggesting that the effects of the Black Summer fires have varied markedly between species, as fire severity and burn extent had little effect on the occupancy of forest habitat by D. rhodogaster. The occurrence of D. rhodogaster across the landscape
post-fire is not unexpected given that the long and narrow bodies of these snakes are well suited to seeking thermally buffered refugia to avoid mortality during wildfires (Pausas, 2019). Soil is an effective buffer against lethal tem- peratures, with depths as shallow as 6 cm being sufficient to reduce temperatures to c. 30 °C during surface fires (Bradstock&Auld, 1995), which is significantly below lethal temperatures for several closely related elapid snakes (Heatwole & Taylor, 1987). Given that D. rhodogaster is a terrestrial snake that often shelters under debris, it is plaus- ible that the animals may have persisted in situ in buffered microsites rather than recolonizing from adjacent unburnt areas (Pausas, 2019). Post-fire composition of reptile com- munities has previously been found to be better explained by in situ persistence than by recolonization for adjacent unburnt regions (Santos et al., 2022). Similarly, the post-fire occurrence of D. rhodogaster is
likely to have been assisted by the low metabolic rates and energy demands that D. rhodogaster shares with other reptiles (Else&Hulbert, 1981). These lowenergetic demands are complemented by the availability of the small skinks on which the snakes prey (Shine, 1981), which are often abundant in post-fire environments (Lunney et al., 1991). Although we did not quantify prey availability,we frequent- ly observed small skinks (e.g. Lampropholis spp. and Saproscincus mustelinus) at burnt sites, suggesting that food was amply available for snakes after the fires. Understanding the role of prey species in driving the occurrence of snakes post-fire could be an important focus of future research. Our analysis of post-fire records showed c. threefold
more D. rhodogaster observations in areas thatwere unburnt (Fig. 3). However, the presence of records in burnt areas during the 12 months immediately following the fires, in- cluding in areas burnt at high severity, suggests that these snakes survived the fires. The number of detections must be interpreted cautiously, as records from the databases used were collected in a non-systematic manner and are thus open to sampling bias. For example, after the Black Summer bushfires, many reserves were closed to the public for varying periods of time because of safety concerns and therefore would not have been accessible to citizen scien- tists. Covid-19 probably also decreased the input of records because of restrictions on the movements of citizen scientists (Stenhouse et al., 2022). Therefore, although most records of D. rhodogaster in the 2 years after the
fires were from unburnt areas, it is important to note that records from burnt areas may have been under-reported because citizen scientists had less access to these areas. Our habitat suitability model (Fig. 2b) predicted a much
broader potential distribution for D. rhodogaster than is evident from previous occurrence records (Fig. 2a). Our habitat suitability model predicted that the range of D. rhodogaster extends north of Hunter Valley at elevations .250malong the Great Dividing Range towards the border with Queensland (Fig. 2b,c). It is possible that our model overestimates the distribution of D. rhodogaster because it extends the range of the species into areas where there are no records in the Atlas of Living Australia. However, the reliability of our model is strengthened by published records of D. rhodogaster near Gloucester and Tenterfield in northern New South Wales (Fig. 2a), as well as by a spe- cimen collected from the Tenterfield region in November 2020 (Australian Museum, R.188326; Goldingay et al., 1996; Daly & Lemckert, 2011), none of which are reported in the Atlas of Living Australia or included in our model. These populations north of Hunter Valley are probably genetically distinct as the valley is a dispersal barrier for many woodland reptiles (Chapple et al., 2011). Moreover, they may be heavily fragmented or patchily distributed. Further studies are warranted to confirm the relationship between populations separated by the valley and to confirm whether northern populations warrant additional conserva- tion measures. This is particularly important as much of the predicted range of D. rhodogaster north of Hunter Valley was burnt in the Black Summer bushfires and because both published records from the region are from land used for recent or ongoing native forestry (Goldingay et al., 1996; Daly & Lemckert, 2011). Given that the reptile fauna of north-eastern New South
Wales has been extensively surveyed (e.g. Milledge 1993; Daly et al., 2011) and there are few reliable records of D. rho- dogaster from the region, it is possible that biotic factors such as habitat type or competition may be restricting the species. However, because the literature records suggest that D. rhodogaster does occur in north-eastern New South Wales (Goldingay et al., 1996; Daly et al., 2011) and our suitability model suggests that the species will be geographically restricted to elevated areas with a cool climate, we believe it is more likely that survey efforts using methods appropriate to detect this cryptic species have been insufficient in climatically suitable habitats. Consequently, we recommend that targeted searches for D. rhodogaster are undertaken in areas of suitable habitat (e.g. high-altitude forest) in this region to better determine its status and how it is affected by fire. Overall, the data on D. rhodogaster occupancy in post-
fire environments that we have collated from our own sur- veys and the Atlas of Living Australia suggest that even though a considerable portion of the known and predicted
Oryx, 2024, 58(6), 769–778 © The Author(s), 2024. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605324000048
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