Grass Skink Research Articles

Habitat loss and degradation reduce the abundance of the glossy grass skink, Pseudemoia rawlinsoni

Context Habitat loss and degradation are major drivers of biodiversity loss worldwide. In particular, wetland environments are being removed and degraded faster than any other terrestrial habitat on earth. The loss and degradation of wetlands has been particularly pronounced in south-eastern Australia. Aims Here we investigated the impact of habitat loss and degradation on the Data Deficient glossy grass skink (Pseudemoia rawlinsoni), a species that predominantly favours wetland vegetation in south-eastern Australia. Methods We established artificial cover-object (roofing tiles) survey grids in paired remnant and disturbed sites at six locations across Victoria, Australia, and surveyed for skinks between November 2021 and April 2022. Key results Sites at which glossy grass skinks occur are characterised by tall dense vegetation, with a high cover of matted biomass. Thermal profiles within these complex vegetation structures remain much cooler during hot days, and warmer during cold nights, than external temperatures. Nearby disturbed sites (i.e. grazed or mowed areas within dispersal distance of remnant sites) are generally devoid of skinks, have very low and structurally simple (open) vegetation, and have thermal regimes that offer lizards no respite from high summer temperatures. We found that roofing tiles are an effective way to survey for glossy grass skinks; even on cool cloudy days, the temperature of tiles, and the lizards sheltering beneath them, are often much higher than ambient temperatures. Conclusions These findings implicate habitat loss and degradation as having a substantial negative impact on glossy grass skink presence and abundance; skinks largely avoid disturbed areas, even at sites immediately adjacent to remnant habitat. This may be driven not simply by the removal of tall and dense vegetation structures, but the consequent loss of the optimal thermal buffer afforded by such structures. Implications Our study emphasises the threat that habitat loss and degradation pose to wetland species in Australia, and throughout the world.

Determining the generation length and level of morphological and genetic differentiation in the Data Deficient glossy grass skink (Pseudemoia rawlinsoni)

Context Human activities are having a significant impact on biodiversity worldwide, to the extent that we are in the midst of the sixth mass extinction event. Although a substantial proportion of species globally have an elevated risk of extinction, some species are poorly known and there is insufficient information available to adequately assess their risk of extinction. Aims and methods One such species is the glossy grass skink (Pseudemoia rawlinsoni), a widespread but enigmatic lizard species in south-eastern Australia. In order to improve our knowledge of its life history, and particularly its generation length, we examined museum specimens collected from across the range of the species, supplemented with measurements from field-caught individuals. Key results We estimated that the species reaches sexual maturity in 3 years, at approximately 40 mm snout–vent length. Its generation length was estimated as 5 years. Sexual dimorphism was evident, and female body size was positively related to litter size. Although there was no evidence for substantial variation in morphology across the range of the glossy grass skink, a phylogeographic analysis using mitochondrial DNA sequence data (ND4) revealed the presence of seven genetic sublineages (up to 5.1% genetic divergence) within the species. Conclusions The glossy grass skink appears to be a single, but widespread and genetically variable, species. Implications Our study demonstrates how a targeted, multifaceted study can be effective at rapidly gathering data that can be used to contribute vital information to the assessment of extinction risk in Data Deficient species.

Capturing uncatalogued distribution records to improve conservation assessments of data‐deficient species: a case study using the glossy grass skink

AbstractEffective conservation planning is often predicated on detailed and current information about a species' geographical distribution. However, traditional sources of occurrence data (e.g., online biodiversity databases) may be insufficient for estimating the range of rare, poorly understood species that are readily misidentified. Here, we demonstrate a more holistic approach to this problem, using the poorly known glossy grass skink (Pseudemoia rawlinsoni) as a case study. We first compared the relative contribution made (to our geographical knowledge of the species) by online database records, with that of photo‐substantiated records obtained via personal communication (PC). We used ecological niche modelling (ENM) to predict the species' distribution, then performed field surveys at both historical and predicted suitable sites to further clarify its occurrence. 20% of all known records came from the PC method, which resulted in 35 new sites and increased the species' area of occupancy (AOO) by 176 km2. Most records obtained via PC came from the past decade, demonstrating that this method is more effective at elucidating the current distribution. ENM revealed that P. rawlinsoni has a disjunct range, and is mostly a low‐elevation coastal species, with the exception of suitable habitat in parts of the high‐elevation Australian Alps bioregion. The species' AOO has likely declined over recent decades owing to anthropogenic disturbance, given that 38% of the species' predicted range is now cleared agricultural land, and our field surveys failed to detect the species at 52% of historical record sites. Together, these findings provide a robust foundation of geographical knowledge on which to develop strategic conservation actions for the species.

Second report of striped grass skink (Eutropis trivittata) from Gujarat, India

The striped grass skink, Eutropis trivittata (Hardwicke & Gray, 1827) is a wide ranging skink, distributed in northern and eastern India, Pakistan, Afghanistan, Bangladesh and Nepa. The nomen of the species had a murky taxonomic history and for a considerable time period it was known by a junior subjective synonym, E. dissimilis, which was rectified by Amarasinghe et al. (2022). The present communication is the first record of the species from the Saurashtra region of Gujarat state, India. In Gujarat, the species was previously reported from Central Gujarat, based on one specimen found three decades ago.

Factors Associated with Detection Probability and Site Occupancy of the Long-Tailed Skink (<i>Eutropis longicaudata</i>) in the Aluoi Area, Central Vietnam

Lizard species are rarely detected with perfect accuracy, regardless of the method employed. Nondetection of a species at a site does not necessarily mean the species was absent unless the detection probability was 100%. We assessed the influence of site covariates (less disturbed habitat and disturbed habitat) and sample covariates (temperature, humidity, rainfall) on the occupancy of Eutropis longicaudata in the Aluoi area, central Vietnam. Based on detection/nondetection data over nine visits at 40 less disturbed sites and 39 sites with disturbed habitats, the distribution of E. longicaudata was estimated using site occupancy models. From the best model, we estimated a site occupancy probability of 0.595, a 12.05% increase over the naive occupancy of 0.531 at which E. longicaudata skinks were actually observed. The site covariate of the less disturbed habitat was an important determinant of site occupancy, which was not associated with the variable of disturbance habitats. In the combined AIC model weight, p(precipitation), p(temperature), and p(humidity) have 92%, 36%, and 21% of the total, respectively; providing evidence that environmental conditions (especially precipitation) were important sample covariates in modelling detection probabilities of E. longicaudata. In terms of occupancy probability, the combined weight for the ψ(less disturbed habitat) model and the ψ(disturbed habitat) model were 60% and 32%, respectively. Our results substantiate the importance of incorporating detection and occupancy probabilities into studies of habitat relationships and suggest that the less disturbed habitat associated with weather conditions influence the occupancy of E. longicaudata in central Vietnam.

Herpetofauna of the Amarkantak Plateau in central India

I conducted herpetofaunal surveys in poorly explored sections of Central India: The Amarkantak Plateau; The Son, Johila, and Narmada river lowlands; parts of the Maikal Mountain Range; and pockets of the core zone area of Achanakmar-Amarkantak Biosphere Reserve. I recorded a total of 61 species (17 amphibian and 44 reptilian). Noteworthy findings included the rediscovery of the Critically Endangered Sacred Grove Bush Frog (Philautus sanctisilvaticus) at its type locality after 54 years, new state records for Dobson’s Burrowing Frog (Sphaerotheca dobsonii) and Beddome’s Grass Skink (Eutropis beddomii), and significant new distributional records for a number of species. This study highlights the importance of landscape-level, long-term fieldwork to untangle the hidden diversity of the Amarkantak Plateau.

Contrasting responses of lizard occurrences to burrowing by a critically endangered seabird

Seabirds are considered ecosystem engineers, because they facilitate ecosystem functioning (e.g., nutrient cycling), crucial for other marine and terrestrial species, including reptiles. However, studies of seabird-reptile interactions are limited. Here, we assessed the influence of the ‘Critically Endangered’ Whenua Hou Diving Petrel (Pelecanoides whenuahouensis) on the occurrence of two threatened skinks, Stewart Island green skink (Oligosoma aff. chloronoton) and southern grass skink (O. aff. polychroma). We surveyed skinks for 26 consecutive days at 51 sites with and 48 sites without Diving Petrel burrows in the dunes on Codfish Island (Whenua Hou), New Zealand. We used occupancy modelling to assess the influence of burrows on the occurrence of skinks, while accounting for other factors affecting occupancy (Ψ) and detection probabilities (p). Diving Petrel burrows had a contrasting effect on the occurrence of skinks. On average, ̂Ψ of Stewart Island green skinks was 114% higher at sites with burrows compared to sites without, while ̂Ψ of southern grass skinks was only 2% higher. Occurrence of both skinks was negatively influenced by the presence of the other skink species. On average ̂p were low: 0.013 and 0.038 for Stewart Island green and southern grass skinks, respectively. Stewart Island green skinks appear attracted to burrows, which might facilitate thermoregulation (i.e., shelter from temperature extremes). The larger Stewart Island green skinks may subsequently exclude the smaller southern grass skinks at burrows, causing the contrasting relationships. We suggest that these interspecific interactions should be considered when implementing conservation management, e.g., through the order of species reintroductions.

Description of a new long-tailed skink (Scincidae: Trachylepis) from Angola and the Democratic Republic of the Congo.

Angola and the Democratic Republic of the Congo are relatively unknown in terms of their herpetological diversity. Based on specimens collected in the Congolese region of the Katanga and the northeast of Angola during the first decades of the twentieth century, de Witte and Laurent independently suggested, based on morphological and coloration differences, that populations of T. megalura of these regions could belong a new "race". We compared specimens of T. megalura (including the type specimens of T. megalura and T. massaiana) with Angolan and Katangan museum specimens as well as newly collected specimens from Angola. Coloration pattern and morphological characters, in combination with substantial divergence in the 16S mitochondrial gene, confirm the distinctiveness of the west Central African form, and it is here described as a new species. Data regarding its natural history, ecology and global distribution are presented.

Species composition and abundance estimates of reptiles in selected agroecosystems in southern Western Ghats, India

Species composition and abundance of reptiles in selected agroecosystems in Thrissur plains, near Palghat Gap, southern Western Ghats in India, was studied from January 2017 to May 2017. The agroecosystems surveyed were coconut, cashew & rubber plantations, home garden, paddy field, and botanical garden. Time-constrained visual encounter surveys of a total effort of 360 man-hours were done in the field. Coconut and cashew plantations reported the highest species richness with 11 species each, while the highest number of sightings (159) were recorded from botanical garden. Bronze Grass Skink Eutropis macularia was the most abundant species in agroecosystems. Correspondence analysis was done to compare the reptilian diversity in the agroecosystems. The reptile fauna of home garden and paddy field were found to be more distinct than the rest of the agroecosystems. A total of 17 species of reptiles were recorded during the study, thus highlighting the significance of agroecosystems in acting as important buffer landscapes for reptiles.

Current Population Status of Diurnal Lizards of Karachi, Pakistan

Five districts of Karachi (East, West, South, Central and Malir) contain resident populations of lizards. During the present studies the current status of diurnal lizards of Karachi was investigated. The faunistic studies were based on seven species from three districts East, South and Malir of Karachi. 182 lizards were captured belonging to seven species, six genera and four families; Agamidae, Scincidae, Lacertidae and Varanidae. Among the 182 captured lizards were 56 Indian Garden Lizards, Calotes versicolor ; 20 Indian Spiny-tailed Lizards, Uromastyx hardwickii ; 72 Bronze Grass Skinks, Mabuya macularia ; 8 Striped Grass Skinks, Mabuya dissimilis ; 15 Indian Fringe-toad Sand Lizards, Acanthodactylus cantoris ; 10 Long-tailed Desert Lacertas, Mesalina watsonana , and 1 Indian Monitor Varanus bengalensis . The results of the present study indicate that the current status of diurnal lizards, i.e., Indian Garden Lizard ( Calotes versicolor ), Bronze Grass Skink ( Mabuya macularia ), Striped Grass Skink ( Mabuya dissimilis ), Indian Fringe-toad sand Lizard ( Acanthodactylus cantoris ), and Long-tailed Desert Lacerta ( Mesalina watsonana ) are common in three selected districts of Karachi, while the Indian Spiny-tailed Lizard ( Uromastyx hardwickii ) and Indian Monitor lizard ( Varanus bengalensis ) have been recorded as threatened species. Uromastyx hardwickii is an endangered species and is already included in the IUCN Red List and CITES Appendix. Internationally, 25% of reptiles are listed as threatened (IUCN, 2002). In Pakistan some lizard species are threatened. Present studies also recorded Uromastyx hardwickii and Varanus bengalensis as threatened species in the three districts of Karachi. The Brilliant Agama ( Trapelus agilis isolepis ) was not found in the three districts of Karachi. Either it is threatened or has gone extinct or has been shifted to other habitats due to destruction of habitat and increase of human population.

Climate change impacts on fitness depend on nesting habitat in lizards

Summary 1. Through nest-site selection, mothers exert control over the incubation environment to which eggs are exposed, which in turn can affect offspring fitness. The strong relationship between offspring quality and incubation temperature in many ectotherms suggests that contemporary climate change could modify the fitness benefits gained from such behaviour. 2. We used life-history data from a tropical lizard (the long-tailed skink, Eutropis longicaudata) to show that a natural dichotomy in nesting habitat directly influences fitness, but that higher ambient temperatures in recent years are having a disproportionate impact on ‘optimal’ nest sites. 3. Gravid lizards either lay eggs beneath rocks in natural habitat or inside a concrete wall in human-modified habitat, where incubation temperatures are higher. Consequently, females using artificial habitat produced larger hatchlings that matured earlier and had higher rates of survival than conspecifics using natural habitat. 4. Ambient temperatures have impacted artificial habitats disproportionately over the last decade by increasing nest temperatures in artificial habitat three times that of natural habitat (1·5 vs. 0·5 °C, respectively). This has reversed nest-site quality by lowering offspring viability of artificial nest sites, but has increased offspring viability of natural nest sites. 5. Climate change has overridden the fitness benefits derived from nesting in artificial habitats, but has caused a resultant increase in the fitness benefits derived from nesting in natural habitats. Laboratory incubation experiments confirm that these patterns are attributed to temperature. 6. Our study highlights the interactive effects of disparate human environmental impacts on fauna; by creating the concrete wall, human habitat modification initially conferred fitness benefits by increasing incubation temperatures, but human-induced climate change has raised nest temperatures above the point at which fitness is reduced. 7. Contemporary climate change is altering the location and availability of ‘optimal’ nesting habitat, thereby changing the ability of nesting females to adaptively manipulate the phenotypes of their offspring. Consequently, human-induced climate change can lead to some habitats becoming ecological traps.

Survey of the reptiles and amphibians of the montane forests near Tenterfield on the north coast of New South Wales

Surveys were conducted in the area that formally encompassed the forests managed by the New South Wales Forestry Commission (Tenterfield Management Area). Surveys consisted of searches for reptiles along 35 transects, roadside searches, pitfall trapping and targeted surveys. Targeted searches were conducted for amphibians beside creeks, fire dams and swamps. A total of 33 species of reptile and 16 species of amphibian were detected. The highest species richness and density of reptiles occurred in eucalypt forests that contained rock outcrops. Closed forest had the lowest reptile species richness and density. Analysis of the abundance of two species of skink (accounting for 73% of observations) recorded during transect searches found that the Grass Skink Lampropholis delicata had greater abundances on logged plots than on unlogged plots whereas Calyptotis scutirostrum did not differ in its abundance across treatments. The Glandular Frog Litoria subglandulosa and Pugh's Frog Philoria pughi, species currentl...

Predation risk of whole-clutch filial cannibalism in a tropical skink with maternal care

Filial cannibalism, the process of eating one’s own offspring, is relatively common in some animal species and has been particularly well studied in fishes. However, whole-clutch filial cannibalism committed by terrestrial vertebrate parents has rarely been reported. In this study, I describe the existence of whole-clutch filial cannibalism in the long-tailed skink, Mabuya longicaudata, on Orchid Island, Taiwan. When skinks encountered intruders against which they could defend themselves, such as the egg-eating snake, Oligodon formosanus, and the agamid, Japalura swinhonis, most M. longicaudata females would either attack (O. formosanus) or ignore (J. swinhonis) the predator, but when the frequency of intrusions by the intruder, O. formosanus, increased, whole-clutch filial cannibalism occurred. When females feel threatened by O. formosanus, the best choice (especially for gravid females) may be to eat their entire clutch of eggs. This behavior has evolved in this skink, thus providing a rare case of whole-clutch cannibalism by a mother reptile. Two existing hypotheses (decreasing brood size and brood age) to explain wholeclutch filial cannibalism suggest that cannibalistic parents may eat the entire clutch when the costs of caring outweigh the expected benefits. In the current study, my results suggest that whole-clutch filial cannibalism is primarily induced by the presence of predators. Thus, I suggest a hypothesis of predation risk of whole-clutch filial cannibalism, in which filial cannibalism by M. longicaudata increases as the predation risk to its offspring increases. Key words: eggs cannibalized by a skink, Mabuya longicaudata, pregnancy, snake-induced behavior. [Behav Ecol]

Parental care in the long-tailed skink, Mabuya longicaudata, on a tropical Asian island

Parental care has been reported in more than 140 species of reptiles (about 3%), but few records unambiguously demonstrate the selective value of that care. I experimentally investigated the influence of maternal attendance on survival of eggs in the long-tailed skink, Mabuya longicaudata, on Orchid Island, Taiwan, by placing sympatric reptiles, both predators and nonpredators, into nests. Without maternal care, most lizard eggs were eaten by the egg-eating snake, Oligodon formosanus. Female lizards with eggs attacked snakes more often and escaped from snakes less often than did females without eggs. Survival of eggs was lower when females were removed from clutches than when they were left in attendance. All egg loss in unprotected nests on Orchid Island was due to predation by O. formosanus. Size of snakes did not determine whether lizards abandoned egg-free nests or nests with eggs when attacked. Females that attacked egg predators had larger clutches than those that did not attack. Females recognized sympatric lizards and did not attack species that do not prey on eggs or on M. longicaudata, but recognized the predatory snake Elaphe carinata and escaped when that species entered the nest. These findings emphasize the ecological importance of an increased understanding of the function of parental care in reptiles.