Testing the relevance of binary, mosaic and continuous landscape conceptualisations to reptiles in regenerating dryland landscapes

Context Fauna distributions are assessed using discrete (binary and mosaic) or continuous conceptualisations of the landscape. The value of the information derived from these analyses depends on the relevance of the landscape representation (or model) used to the landscape and fauna of interest. Discrete representations dominate analyses of landscape context in disturbed and regenerating landscapes; however within-patch variation suggests that continuous representations may help explain the distribution of fauna in such landscapes

Arboreality, excavation, and active foraging: novel observations of radiotracked woma pythons Aspidites ramsayi

Volume: 56Start Page: 313End Page: 32

Benefits of thermal acclimation in a tropical aquatic ectotherm, the Arafura filesnake, Acrochordus arafurae

The presumption that organisms benefit from thermal acclimation has been widely debated in the literature. The ability to thermally acclimate to offset temperature effects on physiological function is prevalent in ectotherms that are unable to thermoregulate year-round to maintain performance. In this study we examined the physiological and behavioural consequences of long-term exposure to different water temperatures in the aquatic snake Acrochordus arafurae. We hypothesised that long dives would benefit this species by reducing the likelihood of avian predation. To achieve longer dives at high temperatures, we predicted that thermal acclimation of A. arafurae would reduce metabolic rate and increase use of aquatic respiration. Acrochordus arafurae were held at 24 or 32A degrees C for 3 months before dive duration and physiological factors were assessed (at both 24 and 32A degrees C). Although filesnakes demonstrated thermal acclimation of metabolic rate, use of aquatic respiration was thermally independent and did not acclimate. Mean dive duration did not differ between the acclimation groups at either temperature; however, warm-acclimated animals increased maximum and modal dive duration, demonstrating a longer dive duration capacity. Our study established that A. arafurae is capable of thermal acclimation and this confers a benefit to the diving abilities of this snake

The relative importance of habitat quality and landscape context for reptiles in regenerating landscapes

Restoration activities are limited by funding and logistics. To optimise restoration efforts, we need to evaluate the effects of management actions on wildlife populations. In general, site-scale habitat quality has a stronger influence on habitat use by fauna than the landscape context. However, this is yet to be empirically tested for reptiles. In this study, we used model averaging and hierarchical partitioning to compare the relative importance of site-scale habitat quality and landscape context for reptile communities and species in a regenerating woodland landscape in semi-arid Queensland, Australia. Reptiles were surveyed at 55 sites. Habitat quality was assessed using relevant variables based on published habitat-associations for each species or group. Landscape context was assessed using binary, mosaic and continuous descriptions of vegetation cover within 250 m of the survey sites. We found that, in comparison to site-scale habitat quality, the composition of the surrounding landscape had little influence on reptiles, despite testing three alternative approaches for describing landscape context. Nine out of eleven reptile species and groups responded to variation in habitat quality, whereas just one species responded to variation in landscape context. Species richness, diversity, and abundance were unaffected by landscape context, but were influenced by site-scale structural complexity and vegetation type. Our findings suggest that reptiles, in general, benefit from conservation and restoration activities that focus on improving site-scale habitat quality, with increasing the amount and connectivity of surrounding vegetation of lesser value. This study also highlights the importance of better understanding the drivers of reptile distributions and abundances in dryland landscapes

The importance of underground shelter resources for reptiles in dryland landscapes: a woma python case study

For effective fauna conservation and management, ecologists are required to identify the resources that are critical for species to survive, and consider how these are distributed across landscapes. The critical resources usually considered are food and water, but the availability of appropriate shelter resources can be a key driver of habitat suitability for terrestrial reptiles and amphibians. Reptiles are important components of dryland ecosystems, yet we have little understanding about how anthropogenic disturbances affect the availability of shelter resources and reptile survival in drylands. In this study, we used VHF radio-tracking to assess the importance of shelter resources in determining the habitat use patterns of a Near-Threatened reptile species, the woma (Aspidites ramsayi; Pythonidae), in modified and intact dryland landscapes of Queensland, Australia. We compared the structural and thermal attributes of locations that were used, with those that were available. Using an information-theoretic approach, we found that the occurrence of womas was strongly associated with the presence of ground burrows, which are excellent thermal insulators. No other shelter type was capable of buffering our study species from sub-zero temperatures during winter, although summer temperatures of >40 degrees C were buffered by hollow logs and piles of woody debris. Habitat use patterns were influenced more by the occurrence of underground shelters than by habitat type. Clearing status per se (cleared, regrowth or intact) had minimal influence on occurrence. Thermally buffered underground shelters are a vital resource for our focal species, and the availability of this shelter resource drives habitat suitability in modified dryland landscapes. Due to the key trophic role of reptiles in dryland ecosystems, and the excellent thermal buffering capacity of underground shelters, we propose that ground burrows may be potentially considered as keystone structures in drylands, and require a similar level of protection to habitat' or legacy' trees in forested ecosystems

Video link

Here is the link to our pretest video of our experiment