Science for Policy Research findings in brief Project 2.1

Reptiles on the brink: the Australian terrestrial snake and lizard species most at risk of extinction

In brief Background Australia is a hotspot for reptiles; The conservation of Australian reptiles Invasive species were the most it is home to about 10% of the world’s is often overlooked relative to the common threats to the most known species (the largest number concern given to birds and mammals imperilled snakes and lizards, of any country), and over 90% (which typically have higher public followed by agriculture, altered fire of Australian reptile species are profiles). However, many of regimes and climate change. found nowhere else. Australia’s reptiles are declining. Although most of the species Many reptiles are experiencing An important first step in preventing identified were historically more ongoing declines in Australia. their extinctions is identifying the widespread, each of them now A lack of conservation action to species at greatest risk. occurs in a relatively small area. address this has been compounded Our team of almost 30 reptile This makes them vulnerable to by a general lack of knowledge about Australian reptiles; many species experts from universities, museums extinctions caused by a single are poorly known (evidenced by and government agencies across catastrophic event, such as a large fire. the high rate of description of the country has identified the 20 Increased resourcing and conservation new Australian species); and there Australian snakes and lizards at actions are urgently needed to prevent has been limited monitoring for greatest risk of extinction, and extinctions of Australian reptiles. most species. Without adequate estimated the probability that they Our study reveals that business-as- monitoring, it is difficult to assess will be lost within 20 years if there usual could result in the extinction population trends and the impacts is no change in management. of up to 11 species by 2040. of threats, and managers may lose opportunities to prevent No 15 Roma earless dragon, Tympanocryptis wilsoni, Queensland. reptile extinctions because severe Image: Stephen Zozaya population declines are not detected with sufficient time to respond. Undetected extinctions are likely to have already taken place. The Australian Government has committed to averting extinctions, and this first requires identification of the species at most immediate risk. This can forewarn governments, conservation managers and the community so that they can implement emergency care and recovery actions to prevent Further Information extinctions before it is too late. David Chapple – [email protected] Hayley Geyle – [email protected]

Biodiversity and Conservation Science

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About the research We identified 60 Australian snakes modelling to measure and test and lizards (collectively known as the expert predictions. squamates) of high conservation We mapped the distributions of concern for consideration in this the most imperilled species in project, based on internationally order to identify priority regions recognised criteria (IUCN Red List). for research and management. For each of these species, We also examined the key we estimated the probability of threats affecting these species. extinction (in the wild) by 2040 to identify and rank the species Our assessments of extinction at most immediate risk. probability preceded the 2019–20 wildfires, which are likely to have To do this, we gathered all available severely worsened the conservation information on the ecology, threats outlook for many of the species and population trends for each included in our study, and also for species, and provided it to 27 reptile many others that were not included experts from across the country. (but for which the fires may have Each expert was then asked to warranted their inclusion). estimate the probability of extinction of each species over the next two Additionally, we assessed the decades, assuming a continuation probability of successfully re- of current management. Participants establishing wild populations of could decline to provide an estimate two Extinct in the Wild lizards for a particular species if they did not endemic to Christmas Island for have any first-hand experience with it. which reintroduction trials are We collected an average of 19 expert currently underway (Lister’s gecko, estimates of extinction risk for each Lepidodactylus listeri; and the blue- species and performed statistical tailed skink, Cryptoblepharus egeriae).

Key findings We identified six species that are See Table 1 for a list of the 20 species of Australian reptiles, relative to more likely to go extinct than to at greatest risk and their probability historic levels. persist over the next two decades, of extinction by 2040. Comparable assessments have assuming no improvements to current Based on the estimated extinction also been applied to Australian management. These include three probabilities of all 60 species mammals, birds and freshwater fishes. skinks, two dragons and one blind considered, up to 11 snakes and The number of reptiles identified as snake. We found that the species lizards could become extinct by being at high risk of extinction within at greatest extinction risk are not 2040 unless management improves. 20 years is lower than for freshwater always in the higher categories This would represent a marked fishes, but similar to the number for such as Critically Endangered. increase in the rate of extinction birds and higher than for mammals.

Conrad Hoskin in Saltuarius eximius habitat. Image: Conrad Hoskin No 12 Pinnacles leaf-tailed gecko, Phyllurus pinnaclensis, Queensland. Image: Stephen Zozaya

Table 1. The 20 Australian terrestrial snakes and lizards at greatest risk of extinction in Australia, their estimated probabilities of extinction in the wild by 2040, their locations, IUCN Red List conservation status and Environmental Protection and Biodiversity Conservation Act 1999 (EPBC) status — Critically Endangered (CR), Endangered (EN), Vulnerable (VU), unassessed due to recent taxonomic revision or description (N/A) and Not listed.

Rank Species Probability of extinction State IUCN status EPBC Act status

Victoria grassland earless dragon 1 93% Vic N/A EN Tympanocryptis pinguicolla

Fassifern blind snake 2 75% Qld CR Not listed Anilios insperatus

Lyons grassland striped skink 3 71% Qld CR Not listed Austroblepharus barrylyoni

Arnhem Land gorges skink 4 69% NT CR EN Bellatorias obiri

Bathurst grassland earless dragon EN (as part 5 62% NSW N/A Tympanocryptis mccartneyi T. pinguicolla)

Gravel Downs ctenotus 6 52% Qld CR Not listed Ctenotus serotinus

Allan’s lerista 7 46% Qld CR EN Lerista allanae

Christmas Island blind snake 8 41% CI EN VU Ramphotyphlops exocoeti

Cape Melville leaf-tailed gecko 9 39% Qld EN Not listed Saltuarius eximius

Mount Surprise slider 10 37% Qld N/A Not listed Lerista storri

McIlwraith leaf-tailed gecko 11 31% Qld VU Not listed Orraya occultus

Pinnacles leaf-tailed gecko 12 28% Qld CR Not listed Phyllurus pinnaclensis

Condamine earless dragon 13 25% Qld EN EN Tympanocryptis condaminensis

Lake Disappointment dragon 14 21% WA VU Not listed Ctenophorus nguyarna

Roma earless dragon 15 19% Qld EN Not listed Tympanocryptis wilsoni

Lake Disappointment ground gecko 16 18% WA VU Not listed Diplodactylus fulleri

Canberra Grassland earless dragon EN (as part 17 18% ACT N/A Tympanocryptis lineata T. pinguicolla)

Christmas Island forest gecko 18 17% CI EN EN Cyrtodactylus sadleiri

Lancelin Island ctenotus 19 17% WA (LI) CR VU Ctenotus lancelini

Limbless fine-lined slider 20 15% Qld EN Not listed Lerista ameles Key findings(continued) Where are the at-risk species? All of the species are restricted in Many of the species persist in range, with a maximum area of remnant pockets of vegetation All of the species occur in a single occupancy of 56 km2. Most (65%) adjacent to highly developed areas state or territory. More than half of the 20 species at greatest risk (e.g., the Bathurst grassland earless (55%) of the 20 species at greatest have an area of occupancy of dragon Tympanocryptis mccartneyi risk occur only in Queensland. 16 km2 or less, and several species and Allan’s lerista Lerista allanae), Three species occur only on islands: are known from only one location. where they face a high risk of two on Christmas Island, and one These small distributions increase extinction due to continued habitat on Lancelin Island (a tiny low-lying their risk of extinction as a result loss, fragmentation and edge effects. sand island off the coast of of a single catastrophic event, Western Australia). The rough location of species such as a large bushfire. distributions is shown in Figure 1.

Christmas Island (o map) Arnhem Land gorges skink McIlwraith leaf-tailed gecko Christmas Island blind snake Christmas Island forest gecko Cape Melville leaf-tailed gecko Mount Surprise slider Lake Disappointment ground gecko Limbless ne-lined slider Lake Disappointment dragon Lyons grassland striped skink Pinnacles leaf-tailed gecko

Gravel downs ctenotus Allan’s lerista Roma earless dragon Condamine earless dragon Fassifern Valley blind snake

Bathurst grassland earless dragon

Lancelin Island ctenotus Canberra grassland earless dragon

Victoria grassland earless dragon

Figure 1. The locations of the 20 Australian terrestrial snakes and The 20 Australian snakes and lizards at greatest risk of extinciton lizards at most risk of extinction.

No 18 Christmas Island forest gecko, Cyrtodactylus sadleiri, Christmas Island. Image: Jon-Paul Emery Threats cane toads) were a problem for 21% of and may have been underestimated the reptile species considered (due to in our study. At least 23 of Australia’s Considering all 62 reptile species in predation, poisoning or direct habitat reptile species were substantially our assessment (including the two destruction). affected by the 2019–20 Black Extinct in the Wild Christmas Island Summer bushfires, including five species), we found that invasive Agriculture (impacting 45% of species), considered in this study. It is still too animals and plants were the most changing fire regimes (impacting 36% early to determine the short- and common threat, impacting 67% of of species), and climate change and long-term impacts of the fires for species. Weeds impacted the most severe weather (impacting 31% of individual species, but it is possible species (40%), followed by predation species) were also important threats that the fires have increased their by feral cats (29%) and red foxes (16%). facing the most imperilled terrestrial likelihood of extinction. Other invasive animals (black rats, snakes and lizards. See Figure 2 for the full list of threats feral pigs, deer, feral horses, invasive The increasing impacts of climate and how many species they impact. invertebrates, oriental wolf snakes and change are not yet well understood,

Pinnacles leaf-tailed gecko habitat. Image: Conrad Hoskin

Development (13) Agriculture (28) Mining (7) Transport (1) Biological resource use (8) Human intrusions (2) Natural system change (22) Invasive species (42) Pollution (5) Climate, weather (19)

0510 15 20 25 30 35 40 45 No. of species affected No 9 Cape Melville leaf-tailed gecko Figure 2. The number of Australian terrestrial snakes and lizards affected by different threats. Saltuarius eximius, Queensland. Dark grey bars represent the 20 species at greatest risk, while light grey bars represent all Image: Tim Lamman other species considered in this study. The total number of species affected by each threat is provided in brackets. Note that natural system change includes changes to fire patterns.

BELOW: No 16 Lake Disappointment ground gecko, Diplodactylus fulleri, Western Australia. Image: Brad Maryan BELOW: No 19 Lancelin Island ctenotus, Ctenotus lancelini, Western Australia. Image: Brad Maryan

Cited material This factsheet summarises the key findings of the following paper, which can be referred to for further detail including a full description of the research method and findings: Geyle, H.M., Tingley, R., Amey, A.P., Cogger, H., Couper, P.J., Cowan, M., Craig, M.D., Doughty, P., Driscoll, D.A., Ellis, R.J., Emery, J-P., Fenner, A., Gardner, M.G., Garnett, S.T., Gillespie, G.R., Greenlees, M.J., Hoskin, C.J., Keogh, J.S., Lloyd, R., Melville, J., McDonald, P., Michael, D.R., Mitchell, N.J., Sanderson, C. Shea, G.M., Sumner, J., Wapstra, E., Woinarski, J.C.Z., and Chapple D. (2020). Reptiles on the brink: identifying the Australian terrestrial snake and lizard species most at risk of extinction. Pacific Conservation Biology. https://doi.org/10.1071/ PC20033

Additional reading: Implications and recommendations Tingley, R., et al. (2019). Geographic and taxonomic patterns of extinction The probability of up to 11 extinctions and the community so that they can risk in Australian squamates. of Australian terrestrial snakes and implement emergency care and Biological Conservation 238, 108203. lizards by 2040 is high without recovery actions to prevent potential improvements in conservation extinctions before it is too late. investment and management. Our findings will be of importance Snakes and lizards have received to policy-makers in state, territory relatively little conservation resourcing and Commonwealth government compared to mammals and birds; agencies and funding bodies, as well this must change if extinctions are as conservation land managers and to be prevented. researchers looking to prioritise and apply research and management By identifying the species at greatest actions for threatened terrestrial risk, this research may forewarn snakes and lizards. governments, conservation managers

Further Information David Chapple – [email protected] Hayley Geyle – [email protected]

This project is supported through funding from the Australian Government’s National Environmental Science Program.