Wind of change: A diurnal skink thermoregulates between cooler set-points and for an increased amount of time in the presence of wind

Wind has the potential to dramatically alter the thermal landscape of habitats, and consequently to affect how ectotherms thermoregulate. However, few studies have directly assessed if wind alters thermoregulation by ectotherms. We compared the thermoregulation of a heliothermic, New Zealand skink under three treatments: no wind, wind at 2 m/s and wind at 6 m/s. We provided captive skinks with housing in which their preferred body temperature was only achievable inside a wind tunnel. During experimental treatments with wind, airflow was generated through the wind tunnel while the maximum available operative temperature remained consistent among treatments. Skinks were able to move in and out of the wind tunnel. Using thermal bio-loggers, we recorded near-continuous skin temperatures of skinks over 90 min. Contrary to our expectations, more skinks tended to thermoregulate in the two wind treatments compared to the treatments without wind (P=0.062) and of the skinks that did thermoregulate, those in the two wind treatments thermoregulated for significantly longer than those in the treatment without wind. The set-point temperatures that skinks thermoregulated between became significantly cooler as windspeed increased, despite skinks having access to the same operative temperatures. Overall, our study suggests that wind has the potential to significantly change the temperatures selected by lizards, even when comparable temperatures are available; wind is therefore an important environmental parameter to consider when studying the thermal ecology of ectotherms, including in the context of climate change.

The ecology of sleep in non-avian reptiles

Sleep is ubiquitous in the animal kingdom and yet displays considerable variation in its extent and form in the wild. Ecological factors, such as predation, competition, and microclimate, therefore are likely to play a strong role in shaping characteristics of sleep. Despite the potential for ecological factors to influence various aspects of sleep, the ecological context of sleep in non-avian reptiles remains understudied and without systematic direction. In this review, we examine multiple aspects of reptilian sleep, including (i) habitat selection (sleep sites and their spatio-temporal distribution), (ii) individual-level traits, such as behaviour (sleep postures), morphology (limb morphometrics and body colour), and physiology (sleep architecture), as well as (iii) inter-individual interactions (intra- and inter-specific). Throughout, we discuss the evidence of predation, competition, and thermoregulation in influencing sleep traits and the possible evolutionary consequences of these sleep traits for reptile sociality, morphological specialisation, and habitat partitioning. We also review the ways in which sleep ecology interacts with urbanisation, biological invasions, and climate change. Overall, we not only provide a systematic evaluation of the conceptual and taxonomic biases in the existing literature on reptilian sleep, but also use this opportunity to organise the various ecological hypotheses for sleep characteristics. By highlighting the gaps and providing a prospectus of research directions, our review sets the stage for understanding sleep ecology in the natural world.

Eurythermic Sprint and Immune Thermal Performance and Ecology of an Exotic Lizard at Its Northern Invasion Front

AbstractThermal performance of immunity has been relatively understudied in ectotherms, especially in the context of invasive species or in relation to other fitness-related traits and thermoregulatory patterns in the field. For reptiles, thermal biology is a primary factor determining physiological performance and population viability, and suboptimal thermal conditions may limit the expansion of exotic species along the edges of their invasion fronts. This study examined thermoregulatory ecology and thermal performance of immunity and sprinting in a population of Mediterranean geckos (Hemidactylus turcicus) at the northern edge of their invasion front in a temperate zone of the United States. In the field, we quantified temperatures of geckos of varied age classes in relation to air, wall, and refugia temperatures. We also quantified temperature-dependent sprint performance and immune function in field-collected geckos to detail thermal performance patterns that may contribute to the capacity for this species to invade cool climates. Although body temperature (T_b) of wild-caught geckos correlated with wall temperature, average T_b exhibited wide distributions, suggesting eurythermy. Furthermore, the thermal performance of immune swelling responses to phytohemagglutinin injections and sprinting was optimized over a similarly wide temperature range that overlapped with the field T_b's that suggest eurythermy in this species. The wide thermal performance breadths in these traits could buffer against variation in factors such as pathogen exposure and environmental temperatures that could otherwise suppress functional performance. Thus, eurythermy of sprint and immune performance may facilitate the invasive potential of H. turcicus.

Barking up the right tree: comparative use of arboreal and terrestrial artificial refuges to survey reptiles in temperate eucalypt woodlands

Context Artificial refuges (cover boards) are a popular method to survey and monitor herpetofauna worldwide. However, one limitation of using artificial refuges in terrestrial environments is the low detection rates of arboreal species. Furthermore, destructive search techniques can damage critical microhabitat such as exfoliating rock or flaking bark of mature trees. Aim We tested a non-destructive, passive method of sampling arboreal reptiles in fragmented agricultural landscapes in south-eastern Australia. Methods We installed 84 artificial bark refuges consisting of strips of non-toxic, closed-cell foam attached to eucalypt trees in 13 patches of remnant vegetation. We used Bayesian statistics to compare differences in detection rates among artificial bark refuges, terrestrial artificial refuges and active searches of natural habitat over a 4-year period. Key results Active searches combined with terrestrial artificial refuges detected the highest number of reptile species, including several cryptic fossorial species. Artificial bark refuges detected, on average, 132 times more individuals of the arboreal southern marbled gecko, Christinus marmoratus, than did terrestrial refuges. Gecko abundance patterns were related to tree characteristics such as tree size, bark thickness and stand basal area, as well as survey year. Conclusions Traditional survey methods such as terrestrial cover boards, in combination with active searches of natural habitat, may significantly underestimate counts for arboreal gecko species. Implications Artificial bark refuges provide a cost-effective, non-destructive and durable method for surveying and monitoring arboreal reptiles in woodland environments over short to medium time frames. Foil-backed, closed-cell foam has broad application for use in spatial capture–recapture studies and long-term monitoring of arboreal reptiles. This method also may be effective for procuring records of threatened arboreal geckos or as a solution for providing temporary habitat in ecological restoration projects.

Comparative use of active searches and artificial refuges to survey reptiles in temperate eucalypt woodlands

Context In many parts of the world, artificial refuges (ARs) are increasingly used to survey different kinds of herpetofauna. Despite gaining popularity, the merit of using ARs compared with standardised active searches remains poorly known, as does their application in regions that support species exhibiting varied life-form strategies. Aims We examined the effectiveness of using two survey methods, active searches and ARs (corrugated steel, roof tiles and three different timber refuges), to detect herpetofauna in a range of eucalypt-woodland communities in south-eastern Australia. Methods We collected count data over a 12-year period from three independent long-term biodiversity monitoring programs in southern New South Wales. We used generalised linear models to compare detection probabilities among survey methods (active searches versus ARs) and among ARs, for each study area. Key results In all study areas, active searches detected the highest mean species richness per site. However, both methods provided complimentary species, thereby maximising species inventory at a regional scale. Species more likely to be detected in active searches included diurnally active, terrestrial and arboreal heliotherms, whereas species detected more frequently using ARs included nocturnal thigmotherms. Conclusions A combination of active searches and AR types is required to provide regional-scale representative reptile assemblages, although more than five consecutive surveys may be needed before species accumulation curves reach plateaux. In future studies, we recommend using stacks of corrugated steel to detect heliothermic Scincidae and arboreal Gekkonidae, roof tiles to detect thigmothermic Pygopodidae and railway sleepers to detect cryptozoic Elapidae and tunnel-dwelling Gekkonidae. Implications Using a combination of ARs and active searches will increase the chance of detecting both common and cryptic species and deploying corrugated steel provides a cost-effective method for surveying reptiles in long-term studies.