A demographic framework for understanding fire‐driven reptile declines in the ‘land of the lizards'

Abstract

Background: Fire creates habitats for many animals but changes in fire activity threaten species worldwide. While conservation assessments routinely identify fire as a threat to lizards and snakes, the processes underlying fire-driven population declines have received less attention. Assessing the effects of fire on demographic processes -survival, reproduction and movement -provides a means to identify mechanisms of population declines and forecast population changes. Here, we synthesize how inappropriate fire regimes contribute to declines of animal populations, using threatened Australian squamates as a case study. Methods:We applied a demographic framework in a systematic review to identify fire characteristics and interacting threats associated with population declines in imperilled Australian squamates (n = 88). We reviewed primary literature and conservation assessments on these species and classified fire-related threats according to seven key mechanisms of population decline, five fire-regime characteristics, and eight interacting threats.Results: Inappropriate fire regimes threaten 43% of Australian squamates of conservation concern, including geckos, skinks and snakes. Our analysis indicates that high fire intensity and severity, high fire frequency, and large fires are the main causes of fire-related population declines, particularly via their impacts on survival. Low fire frequency also contributes to declines of some species through reduced survival or reproductive success. Weed invasion and predation are observed or predicted to interact with fire to amplify reptile declines. Our results also reveal a dearth of robust empirical studies on squamates of conservation concern. Main conclusions:The demographic framework applied here will help forecast population changes in a new era of fire. By focusing on processes that are relevant to squamate populations globally, we anticipate that the framework will help diagnose causes of population declines in ecosystems that experience fire, and quantify the consequences of alternative management actions, including urgent conservation interventions after megafires.

Meta‐analysis reveals impacts of disturbance on reptile and amphibian body condition

“…For example, early successional species in postfire landscapes (Santos et al, 2022), urban adapters (Kark et al, 2007) and open-habitat specialists (Pike et al, 2011). Herpetofauna responses can depend on disturbance characteristics, species traits and environmental conditions (Chergui et al, 2019(Chergui et al, , 2022Murray et al, 2019;Putman & Tippie, 2020;Santos et al, 2022;Sparling et al, 2010). For example, in human dominated disturbance types (e.g.…”

“…fire, species invasions) (Rykiel Jr, 1985; Sergio et al, 2018). Disturbance causes direct mortality of wildlife while also threatening survival through indirect impacts such as altered environmental conditions, habitat structure, food resources and species interactions (Santos et al, 2022; Sergio et al, 2018). Deepening our understanding of how disturbances impact wildlife is critical for future conservation management (Cross et al, 2021; Gibbons et al, 2000; Parmesan et al, 2022).…”

Increasing threat of wildfires: the year 2020 in perspective: A Global Ecology and Biogeography special issue

“…The papers in this special issue include vulnerability assessments of plant species (Gallagher et al, 2022), vertebrate fauna (Legge et al, 2022), squamates of conservation concern (including geckos, skinks and snakes, Santos et al, 2022), invertebrates (Marsh et al, 2022) and ecosystems (Keith et al, 2022). A common theme across these studies is that vulnerability assessments must consider fire response traits in combination with information on fire regimes, and not just the proportion of a species' range or ecosystem extent that was subject to fire.…”

“…Legge et al (2022) identify 91 faunal taxa that, as a result of the Black Summer fires, are now eligible for threatened species listing, or uplisting. Santos et al (2022) find that 43% of Australian squamates of conservation concern are threatened by changes in fire regimes. Marsh et al (2022) find that the Black Summer fires burned at least 50% of the range of nearly 800 invertebrate taxa, with vulnerability assessments hampered by major knowledge gaps in invertebrate ecology.…”

Monitoring the population status of a secretive lizard, the threatened heath skink Liopholis multiscutata, in south‐eastern Australia using surrogate metrics: An update

“…A recent analysis of monitoring data, collected between 2007 and 2018 for the four Victorian populations, revealed a general ongoing decline of all four populations (Brown et al, 2020). This decline is most likely due to the environmental fluctuations of fire and predation (especially by introduced canids) (Brown et al, 2019; Chapple et al, 2019; Department of Sustainability and Environment, 2000; Santos et al, 2022); there is limited understanding of the ways in which fire shapes these semi‐arid environments and the consequences for resident reptiles.…”