Eulamprus Research Articles

Impacts of the Gospers Mountain Wildfire on the flora and fauna of mining-impacted Newnes Plateau Shrub Swamps in Australia’s Eastern Highlands

ABSTRACT The Gospers Mountain Fire was the largest wildfire on record in New South Wales. All of the swamps on the Newnes Plateau were burnt, with some areas experiencing fire of very high severity. Despite this severity, the vegetation in all unmined reference swamps recovered relatively quickly, with substantial vegetation cover and biomass returning within 10 weeks. These swamps retained most of their peat and plant species, and both their surveyed endangered fauna species (Blue Mountains Water Skink Eulamprus leuraensis; Giant Dragonfly Petalura gigantea). This demonstrated the resilience of reference Newnes Plateau Shrub Swamps and their endangered species populations to significant bushfire events. In stark contrast, after the wildfire there was evidence of extensive combustion and oxidization of peat soils in swamps located above the footprint of prior longwall coal mining operations. Populations of endangered species, which were already in significant decline (due to longwall mining impacts on swamp hydrology), are now vulnerable to localised extinctions in these undermined swamps. Mining is ongoing in these areas and failure to protect the remaining Newnes Plateau Shrub Swamps from the hydrological impacts of longwall mining will likely lead to further ecosystem collapse in undermined swamps, and further localised extinctions of endangered species populations in these swamps.

Phylogenetic position of Tropidophorus assamensis Annandale, 1912 with updated morphological data and distributional records

The poorly known northeastern water skink Tropidophorus assamensis is only known from the type locality (Harigaj Range, Sylhet District) in Bangladesh, and few localities in Assam and Mizoram States, north-eastern India. Little is known about the biology including the systematics of the species. In this study, we present for the first time, genetic data (16s rRNA) and inferred its phylogenetic position. In addition to this, we provide updated morphological data along with new distributional records of the species from Mizoram State of north-east India.

Predation and prey-caching of Eastern Water Skinks Eulamprus quoyii by nesting Nankeen Kestrels Falco cenchroides in eastern New South Wales

The breeding diet of a pair of Nankeen Kestrels Falco cenchroides nesting in Beresfield, eastern New South Wales, in 2020 was investigated. By individual prey species, the diet comprised 61.3% reptiles (including two prey species not previously recorded in the Nankeen Kestrel diet—Eastern Water Skink Eulamprus quoyii and most likely Southern Rainbow Skink Carlia tetradactyla), 9.7% birds (including a new prey species—Superb Fairy-wren Malurus cyaneus), 6.4% invertebrates (two crickets: Grylloidea), 3.2% mammals (one House Mouse Mus musculus) and 19.4% unidentified prey items (percentages by number). During 31.5 h of observations, the male delivered 22/31 prey items (71%) and the female delivered 9/31 prey items (29%) to the nest tree. The average delivery rate over the entire nestling period was one prey item per hour. Prey-caching, whereby the female stored lizards in the fork of a tree and later retrieved them and fed them tothe single nestling, was observed. Further studies are needed to obtain well-documented accounts of prey-caching by Australian falcons.

Sperm cryopreservation in an Australian skink (Eulamprus quoyii).

Assisted reproductive technologies for population and genetic management for threatened herpetofauna have grown substantially in the past decade. Here we describe experiments to optimise sperm cryopreservation in a model squamate, the eastern water skink Eulamprus quoyii . Small, concentrated volumes of highly motile spermatozoa were reliably collected from adult male E. quoyii by non-lethal ventral massage. Samples were used to: (1) test whether protein-rich diluents, namely Beltsville poultry semen extender (BPSE) and TES and Tris (TEST) yolk buffer (TYB), improve post-thaw quality metrics compared with Dulbecco's phosphate-buffered saline (DPBS); and (2) compare the efficacy of these diluents in combination with either 1.35M glycerol or 1.35M dimethyl sulfoxide (DMSO) at two freezing rates, fast (approximately -20°C min-1 ) versus slow (-6°C min-1 ). Glycerol and DMSO performed equally well in preserving spermatozoa under slow freezing rates. Under these conditions, the use of the complex diluents BPSE and TYB significantly improved post-thaw total motility compared with DPBS. Complex interactions occurred between cryodiluent type, cryoprotectant and freezing rate when testing fast versus slow freezing rates among treatment groups. Under slow freezing rates, DMSO was better at preserving membrane integrity and motility, regardless of diluent type, but successful fast freezing required complex diluents to support motility and membrane integrity, which has implications for implementation in a field setting.

Sexual selection on performance traits in an Australian lizard with alternative reproductive tactics.

Sexual selection shapes the adaptive landscape in complex ways that lead to trait integration. Much of our understanding of selection comes from studies of morphological traits. However, few studies attempt to quantify the form and direction of selection on performance even though it is predicted to be a more direct target of selection in nature. We measured sexual selection on performance traits (bite force, sprint speed and endurance) in an Australian lizard, the Eastern water skink (Eulamprus quoyii). We first staged 123 contests between size-matched males to investigate whether performance traits were important in determining contest outcome. In a second experiment, we established six breeding populations in large replicate semi-natural enclosures to estimate whether performance traits predicted reproductive success. Our results show that none of the performance measures were important in predicting contest outcome and were not generally strong predictors of reproductive success. However, our analyses suggest a complex fitness landscape driven by males adopting different alternative reproductive tactics (ARTs). We provide a rare test of the role performance plays in sexual selection and highlight the need to test common assumptions regarding the link between maximal performance and fitness. Our results suggest that performance traits may not necessarily be direct targets of sexual selection, but rather indirect targets through their integration with morphological and/or behavioural traits, highlighting a need for more explicit tests of the predicted links between performance and fitness.

Are lizards capable of inhibitory control? Performance on a semi-transparent version of the cylinder task in five species of Australian skinks

Inhibitory control, the inhibition of prepotent actions, is essential for higher-order cognitive processes such as planning, reasoning, and self-regulation. Individuals and species differ in inhibitory control. Identifying what influences inhibitory control ability within and between species is key to understanding how it evolved. We compared performance in the cylinder task across five lizard species: tree skinks (Egernia striolata), gidgee skinks (Egernia stokesii), eastern blue-tongue skinks (Tiliqua s. scincoides), sleepy lizards (Tiliqua r. asper), and eastern water skinks (Eulamprus quoyii). In our task, animals had to inhibit the prepotent motor response of directly approaching a reward placed within a semi-transparent mesh cylinder and instead reach in through the side openings. Additionally, in three lizard species, we compared performance in the cylinder task to reversal learning to determine the task specificity of inhibitory ability. Within species, neither sex, origin, body condition, neophobia, nor pre-experience with other cognitive tests affected individual performance. Species differed in motor response inhibition: Blue-tongue skinks made fewer contacts with the semi-transparent cylinder wall than all other species. Blue-tongue skinks also had lower body condition than the other species which suggest motivation as the underlying cause for species differences in task performance. Moreover, we found no correlation between inhibitory ability across different experiments. This is the first study comparing cylinder task performance among lizard species. Given that inhibitory control is probably widespread in lizards, motor response inhibition as exercised in the cylinder task appears to have a long evolutionary history and is likely fundamental to survival and fitness.SignificanceThe study of lizard cognition is receiving increasing attention. Lizards are a diverse group with a wide range of ecological attributes and represent a model system through which we can test a wide range of hypotheses relating to cognitive evolution. Furthermore, considering their evolutionary history, studying non-avian reptile cognition can help understand the evolution of different cognitive abilities including inhibitory control. Here, we provide a comparison of inhibitory control ability in five lizard species. Consequently, we are able to, firstly, validate a method (the cylinder task) initially developed for the use in mammals and birds, for use in lizards, and secondly, collect valuable data on inhibitory control in a poorly studied group with respect to cognitive ability. Our study suggests non-cognitive factors as a major influence on cylinder task performance, which is in agreement with previous studies of other vertebrates.

Attenuated phenotypic responses of lizard morphology to logging and fire-related forest disturbance

Animals that face natural and human-mediated landscape disturbance processes can demonstrate different modalities of phenotypic variation to influence local population persistence. Differences in the frequency and pervasiveness of environmental variation can cause an individual’s phenotype to demonstrate either directional plasticity (i.e., environmental matching), canalization, or increased trait variance. Furthermore, how important a trait’s influence is on fitness can further mediate the nature of phenotypic outcomes to environmental variation. We explored the effects of multi-decadal chronosequences of logging and fire-related forest disturbance on morphological variation of the generalist lizard species, the Yellow-bellied water skink (Eulamprus heatwolei) in Southern Australia. There was evidence that both logging and fire-related disturbance could influence multiple elements of vegetation structure that would construe a major source of environmental variation for lizards. Nevertheless, neither logging nor fire-related disturbance effects resulted in significant differences in lizard morphological traits. However, there was evidence that years post-fire disturbance was associated with a modest but significant increase in a measure of lizard morphological variance. For the most part, we suggest that lizards exhibit canalization in their morphological responses to disturbance related environmental variation. In forests ecosystems with complex temporal and spatial regimes of environmental variation, canalization of lizard morphology could be expected to ensure phenotypic stability within or across generations to favor geometric, over arithmetic, fitness.

Context-specific response inhibition and differential impact of a learning bias in a lizard.

Response inhibition (inhibiting prepotent responses) is needed for reaching a more favourable goal in situations where reacting automatically would be detrimental. Inhibiting prepotent responses to resist the temptation of a stimulus in certain situations, such as a novel food item, can directly affect an animal's survival. In humans and dogs, response inhibition varies between contexts and between individuals. We used two contextually different experiments to investigate response inhibition in the eastern water skink (Eulamprus quoyii): reversal of a visual two-choice discrimination and a cylinder detour task. During the two-choice task, half of our lizards were able to reach an initial learning criterion, but, thereafter, did not show consistent performance. Only two individuals reached a more stringent criterion, but subsequently failed during reversals. Furthermore, half of our animals were not able to inhibit a pre-existing side preference which affected their ability to learn during the two-choice task. Skinks were, however, able to achieve a detour around a cylinder performing at levels comparable to brown lemurs, marmosets, and some parrot species. A comparison between the tasks showed that reaching the initial criterion was associated with low success during the detour task, indicating that response inhibition could be context-specific in the water skink. To the best of our knowledge, this is the first study to examine inhibitory control and motor self-regulation in a lizard species.

Feral horse impacts on threatened plants and animals in sub‐alpine and montane environments in Victoria, Australia

SummaryFeral herbivores are a major driver of biodiversity loss globally and can alter the structure, composition and functioning of ecosystems. The direct impacts of feral herbivores on plant communities are well studied, but the direct and indirect effect they have on wildlife is not well understood. In Victoria (south‐eastern Australia), a large feral Horse (Equus caballus) population coincides with highly sensitive and nationally endangered Alpine Sphagnum Bogs and Associated Fens communities, and several threatened animal species. We assessed the impact of feral horses on this ecological community and the Alpine Water Skink (Eulamprus kosciuskoi) and the Broad‐toothed Rat (Mastacomys fuscus) at 20 sites with varying levels of horse disturbance. We used scat counts to determine an index of feral horse abundance and quantified impacts associated with their presence in the landscape. Active searches were used for Alpine Water Skink and scat and runway surveys for Broad‐toothed Rat. We also measured the vegetation structure and the abundance of different vegetation types (life forms). Our results suggest that feral horses are associated with vegetation types and characteristics that negatively influence the presence or abundance of Alpine Water Skink and Broad‐toothed Rat. Sites with high horse activity had more low‐growing forbs, and the abundance of Alpine Water Skink was negatively related to this vegetation type. Grasses, sedges, rushes and shrubs were also less dense and lower in height in high horse activity sites, and Broad‐toothed Rat was less likely to be present in areas with these habitat attributes. We recommend that feral horses are controlled to protect these threatened vertebrate species and their Sphagnum bog habitat.

Feral horse impacts: The Kosciuszko Science Conference, Thursday 8 November 2018, Shine Dome, Australian Academy of Science, Canberra

Feral horse impacts: The Kosciuszko Science Conference, Thursday 8 November 2018, Shine Dome, Australian Academy of Science, Canberra

109 Sperm cryopreservation in Eulamprus quoyii (Eastern water skink)

Australia has a rich diversity and high endemism (93%) of reptilian species, the largest family being Scincidae (252 species), yet there continues to be a paucity of reports for gamete cryopreservation in reptilians (Clulow and Clulow 2016 Reprod. Fertil. Dev. 28, 1116-1132, DOI: 10.1071/RD15466). The goal of this study was to collect sperm from a locally abundant skink species (Eulamprus quoyii; Eastern water skink) to examine sperm sensitivity to cryopreservation. Wild-caught males (n=50; snout-vent length=103-126mm) were held in seminatural conditions for the duration of the study. Semen was collected during the breeding season (September-October) using an adapted ventral-massage technique (Molinia et al. 2010 Herp. Cons. Biol. 5, 311-319; retrieved from http://www.herpconbio.org). Sperm metrics (volume, concentration, progressive and total motility, and membrane integrity) were assessed subjectively under light or fluorescence microscopy. Results were compared using ANOVA. Sperm volume (9.43±5.18μL) and concentration (7.79×108±5.32×108 sperm/mL) did not correlate with snout-vent length in adult males (r2=0.025 and r2=0.15, respectively). Due to small volumes, sperm samples (motility >80%) from 4 to 6 males were pooled before allocation across treatments. For all cryopreservation experiments, sperm samples (5-10μL) were loaded into 0.2-mL French straws and frozen using a controlled-rate freezer (Cryobath; −6°C per minute), then plunged into LN. Sperm were thawed in a water bath at 35°C for 10s. In year 1, pooled samples (n=3) were maintained at room temperature (21±1.5°C) either raw, or diluted in PBS, Tris-citrate glucose, TLHepes, or Ham’s F-10 and assessed at 0, 1, 3, 16, 40h. Tris-citrate-glucose-diluted sperm had significantly lower total motility from 3h (36.7±11.5%; P<0.05), decreasing to 1% motility by 16h. Up to 70% motility could be maintained for 16h in all other treatment groups. In year 2, pooled samples (n=3) were cooled to 4°C over a period of 2h, then gradually diluted 1:1 with buffer to a final concentration of either 0.6, 1.35, or 2.7M cryoprotectant (CPA; dimethyl sulfoxide, dimethyl acetamide, glycerol) in PBS or no CPA. Sperm diluted in 1.35 and 2.7M dimethyl sulfoxide in PBS had significantly (P<0.05) higher kinetic rating and proportion of live sperm than control or dimethyl acetamide treatments; 1.35 and 2.7M glycerol were intermediate. In year 3, dilution and cryopreservation using 1.35M CPA in complex diluents, Tris-yolk buffer (20.1±2.6% live) and Beltsville poultry semen extender (29.7±2.0% live), did not significantly improve sperm survival compared to PBS (26.4±2.7% live); however, post-thaw progressive motility (5±1.1%) was significantly (P < 0.05) higher with 1.35M dimethyl sulfoxide Tris-yolk buffer than all other treatment groups. In conclusion, dimethyl sulfoxide yields promise for sperm cryopreservation in a skink, but further studies are required.

Speciation in the mountains and dispersal by rivers: Molecular phylogeny of Eulamprus water skinks and the biogeography of Eastern Australia

AbstractAimTo develop a robust phylogeny for the iconic Australian water skinks (Eulamprus) and to explore the influence of landscape evolution of eastern Australia on phylogeographic patterns.LocationEastern and south‐eastern Australia.MethodsWe used Sanger methods to sequence a mitochondrial DNA (mtDNA) locus for 386 individuals across the five Eulamprus species to elucidate phylogeographic structure. We also sequenced a second mtDNA locus and four nuclear DNA (nDNA) loci for a subset of individuals to help inform our sampling strategy for next‐generation sequencing. Finally, we generated an anchored hybrid enrichment (AHE) approach to sequence 378 loci for 25 individuals representing the major lineages identified in our Sanger dataset. These data were used to resolve the phylogenetic relationships among the species using coalescent‐based species tree inference in *BEAST and ASTRAL.ResultsThe relationships between Eulamprus species were resolved with a high level of confidence using our AHE dataset. In addition, our extensive mtDNA sampling revealed substantial phylogeographic structure in all species, with the exception of the geographically highly restricted E. leuraensis. Ratios of patristic distances (mtDNA/nDNA) indicate on average a 30‐fold greater distance as estimated using the mtDNA locus ND4.Main conclusionsThe major divergences between lineages strongly support previously identified biogeographic barriers in eastern Australia based on studies of other taxa. These breaks appear to correlate with regions where the Great Escarpment is absent or obscure, suggesting topographic lowlands and the accompanying dry woodlands are a major barrier to dispersal for water skinks. While some river corridors, such as the Hunter Valley, were likely historically dry enough to inhibit the movement of Eulamprus populations, our data indicate that others, such as the Murray and Darling Rivers, are able to facilitate extensive gene flow through the vast arid and semi‐arid lowlands of New South Wales and South Australia. Comparing the patristic distances between the mitochondrial and AHE datasets highlights the continued value in analysing both types of data.

Testing domain general learning in an Australian lizard.

A key question in cognition is whether animals that are proficient in a specific cognitive domain (domain specific hypothesis), such as spatial learning, are also proficient in other domains (domain general hypothesis) or whether there is a trade-off. Studies testing among these hypotheses are biased towards mammals and birds. To understand constraints on the evolution of cognition more generally, we need broader taxonomic and phylogenetic coverage. We used Australian eastern water skinks (Eulamprus quoyii) with known spatial learning ability in three additional tasks: an instrumental and two discrimination tasks. Under domain specific learning we predicted that lizards that were good at spatial learning would perform less well in the discrimination tasks. Conversely, we predicted that lizards that did not meet our criterion for spatial learning would likewise perform better in discrimination tasks. Lizards with domain general learning should perform approximately equally well (or poorly) in these tasks. Lizards classified as spatial learners performed no differently to non-spatial learners in both the instrumental and discrimination learning tasks. Nevertheless, lizards were proficient in all tasks. Our results reveal two patterns: domain general learning in spatial learners and domain specific learning in non-spatial learners. We suggest that delineating learning into domain general and domain specific may be overly simplistic and we need to instead focus on individual variation in learning ability, which ultimately, is likely to play a key role in fitness. These results, in combination with previously published work on this species, suggests that this species has behavioral flexibility because they are competent across multiple cognitive domains and are capable of reversal learning.

The impact of wildfire on an endangered reptile (Eulamprus leuraensis) in Australian montane swamps

Intense fire is a key threatening process for the endangered Blue Mountains water skink, Eulamprus leuraensis. This species is restricted to isolated, densely vegetated and waterlogged peat swamps in montane south-eastern Australia. We surveyed 11 swamps (5 unburnt, 6 burnt) over 2 years, before and after the intense spring bushfires of 2013, to quantify the fires’ impacts on these skinks, other lizards and the habitat upon which they depend. Trapping revealed no direct effect of fire on E. leuraensis populations, with skinks persisting in all burnt swamps. Fire modified ground vegetation, virtually eliminating live plants and the dense understorey. Despite the conflagration, vegetation regrowth was rapid with swamp habitat largely recovering in just over 1 year post-fire. Fire thus had only a transitory effect on lizard habitat and a non-significant impact on E. leuraensis numbers. Nonetheless, broader-scale analyses suggest a different story: skinks were more abundant in swamps that had experienced a longer time since major fire. Although the ability of this endangered reptile to survive even intense wildfires is encouraging, fire during prolonged dry periods or an intensified fire regime might imperil skink populations.

Predicting the occurrence of an endangered reptile based on habitat attributes

The endangered Blue Mountains water skink (Eulamprus leuraensis), a habitat specialist known from approximately 60 threatened highland peat swamps, is the sole endemic vertebrate of the Blue Mountains region, Australia. We quantified the species’ habitat associations by surveying 10 such swamps annually for three years. We scored habitat features and trapped skinks, comparing habitat attributes of trap sites where skinks were and were not captured. The distribution of E. leuraensis was non-random: skinks were found at sites with high values for some variables (soil moisture, live vegetation, surface water, understorey density and numbers of burrows) and low values for others (dead vegetation, logs, rocks, bare ground, canopy cover, sunlight penetration and numbers of invertebrates), and were mostly found in sites that were close to surface water and far from trees and logs. Eulamprus leuraensis is widely distributed within swamps, with weak associations between microhabitat variation and skink presence. Skink abundance and mean body size were highest within swamp centres, decreasing towards the margins; larger skinks were found closer to water, gravid female skinks were found at wetter sites and juveniles occupied marginal habitat. Skinks were rarely recaptured >10 m from their original site, with adult males travelling further than adult females and juveniles. We developed a quick field detection method for managers to assess the likely presence of E. leuraensis using two habitat attributes (soil moisture and burrow abundance). We mapped the species’ known and predicted habitat using GIS spatial layers, including locality records, associated vegetation communities and digital elevation models.

Dominance and social information use in a lizard.

There is mounting evidence that social learning is not just restricted to group-living animals, but also occurs in species with a wide range of social systems. However, we still have a poor understanding of the factors driving individual differences in social information use. We investigated the effects of relative dominance on social information use in the eastern water skink (Eulamprus quoyii), a species with age-dependent social learning. We used staged contests to establish dominant-subordinate relationships in pairs of lizards and tested whether observers use social information to more quickly solve both an association and reversal learning task in situations where the demonstrator was either dominant or subordinate. Surprisingly, we found no evidence of social information use, irrespective of relative dominance between observer and demonstrator. However, dominant lizards learnt at a faster rate than subordinate lizards in the associative learning task, although there were no significant differences in the reversal task. In light of previous work in this species, we suggest that age may be a more important driver of social information use because demonstrators and observers in our study were closely size-matched and were likely to be of similar age.

Habitat and Fauna of an Endangered Swamp Ecosystem in Australia’s Eastern Highlands

Temperate Highland Peat Swamps on Sandstone are isolated pockets of moist habitat in the Blue Mountains region of Australia. Although endangered, few detailed studies have been conducted on their distinctive habitats and wildlife. We surveyed 10 swamps annually for 3 years to characterise conditions within swamps, surrounding woodland, and the transitional zone in between. Swamps were distinguished by waterlogged soil, a dense sedge understorey of live vegetation, and a virtual absence of trees, logs and rocks. In contrast, woodland had dry soil, a sparse understorey, many trees and logs, and much dead vegetation. The transitional zone was intermediate in these respects. Faunal species included 5 mammals (29 records), 17 reptiles (452 records) and 1 amphibian (13 records), with lizards comprising >90% of all faunal records. Paradoxically, the sole endangered vertebrate, the Blue Mountains Water Skink (Eulamprus leuraensis) was the most abundant taxon we recorded: a habitat specialist found primarily within swamps (95% of records) and absent from woodland. Other Eulamprus species in the transitional zone (E. heatwolei) and woodland (E. quoyii) occurred at much lower densities. Because E. leuraensis is abundant within montane swamps but absent from surrounding habitats, any disturbance to swamps is likely to imperil populations of this endangered reptile.

Influence of prior contest experience and level of escalation on contest outcome

An individual’s contest history can have a significant effect on their probability of winning a future contest. These winner–loser effects are likely to be mediated by the level of escalation in a contest, although this is rarely considered in the contest literature. We staged contests between size-matched male water skinks (Eulamprus quoyii) in a tournament design to investigate how prior contest success indirectly affected contest outcome through its effects on contest behavior. Moreover, we predicted that the effect of behavioral traits on contest outcome would depend on the level of escalation reached by contestants (non-escalated versus escalated contests). Contest initiation was the best predictor of contest outcome in both non-escalated and escalated contests, and whether an individual initiated a contest depended on prior contest experience. Prior winners were more likely to initiate subsequent aggressive encounters, and by doing so, initiators had an 88 % probability of winning compared to non-initiators in non-escalated contests. However, this effect was mediated by the level of escalation. Initiators in escalated contests had only a 59 % probability of winning compared to non-initiators. These results suggest that the strength of the effect of prior contest experience on behavioral traits varies across contest stages and is consistent with the hypothesis that prior contest experience alters an individual’s perception of its own fighting ability. Our study highlights the importance of considering the level of contest escalation when examining winner–loser effects in predicting contest outcome. Our results show that the effect of prior contest experience on contest initiation varies depending on the level of escalation reached by the contestants. We emphasize the importance of considering the level of contest escalation when examining the influence of prior contest experience on contest outcome.

The impact of fire regimes on populations of an endangered lizard in montane south‐eastern Australia

AbstractThe Blue Mountains water skink (Eulamprus leuraensis; Scincidae) is restricted to less than 40 fragmented swamp sites, all within the Blue Mountains and Newnes Plateau areas of New South Wales, Australia. Climate change is expected to increase fire frequency in the area, potentially degrading habitat quality for this endangered reptile. We quantified lizard abundances in 12 swamps using standardized surveys, and constructed a Global Information System (GIS) database to determine fire‐histories for each swamp since 1967. The abundance of Blue Mountains water skinks was negatively correlated with fire frequency, but not with time since fire. Indirect impacts of fire (mediated via shifts in vegetation density, moisture levels, prey availability and post‐fire predation) may be more important than direct effects in these cool, moist habitats. Although lizards were less common in swamps close to urban areas, and less common in frequently burnt areas, viable populations of this endangered reptile still persist even in anthropogenically disturbed swamps and in swamps that have experienced up to four fires in 20 years. Future research could usefully extend these analyses to other swamps in the locality, and explore the broader impacts of fire regimes on the distinctive flora and fauna of this threatened ecological community.

Sex and boldness explain individual differences in spatial learning in a lizard

Understanding individual differences in cognitive performance is a major challenge to animal behaviour and cognition studies. We used the Eastern water skink (Eulamprus quoyii) to examine associations between exploration, boldness and individual variability in spatial learning, a dimension of lizard cognition with important bearing on fitness. We show that males perform better than females in a biologically relevant spatial learning task. This is the first evidence for sex differences in learning in a reptile, and we argue that it is probably owing to sex-specific selective pressures that may be widespread in lizards. Across the sexes, we found a clear association between boldness after a simulated predatory attack and the probability of learning the spatial task. In contrast to previous studies, we found a nonlinear association between boldness and learning: both 'bold' and 'shy' behavioural types were more successful learners than intermediate males. Our results do not fit with recent predictions suggesting that individual differences in learning may be linked with behavioural types via high-low-risk/reward trade-offs. We suggest the possibility that differences in spatial cognitive performance may arise in lizards as a consequence of the distinct environmental variability and complexity experienced by individuals as a result of their sex and social tactics.