Living in a shallow burrow under a rock: Gas exchange and water loss in an Australian scorpion

The scorpion, Urodacus manicatus (Scorpionida: Urodacidae), inhabits temperate sclerophyll woodland in south-eastern Australia and excavates a shallow burrow into soil beneath a rock. Mean minimum and maximum temperatures within a burrow were respectively higher and lower than outside measurements, and relative humidity within a burrow remained higher than outside the burrow at all times. Using flow-through respirometry, VCO₂ and water loss were measured at three ecologically relevant temperatures (10, 20 and 30 °C) to assess patterns of gas exchange and the temperature dependence of VCO₂ and water loss rates. Daytime VCO₂ corresponds to a lower metabolic rate than reported for the closely related, but more arid region inhabiting species Urodacus armatus and Urodacus yaschenkoi. CO₂ output is continuous at 10 °C; however, at 20 °C scattered sharp depressions are observed and these become more frequent and periodic at 30 °C. Total water loss in U. manicatus is nearly double that in U. armatus, indicative of lessened selective pressure for water conservation within a mesic rather than xeric environment.     

Effect of abiotic factors on the burrow density of some sympatric field murids

The burrow density of sympatric murids in relation to various abiotic factorsviz. maximum and minimum atmospheric temperatures, relative humidity, soil temperature and soil moisture was studied in the agro-ecosystem of village Kakrod-Jind (Haryana) Analysis of monthly recorded data on burrow density revealed a biomodal patterni. e. a peak each during the months of September and March · Of these abiotic factors, soil moisture revealed significant positive correlation with the burrow density whereas relative humidity exhibited invariably the least interaction · However, path co-efficient analysis depicted the direct effects of soil temperature and soil moisture and indirect effect of maximum and minimum atmospheric temperature through soil temperature on the burrow density. The use of path co-efficient analysis in such studies has been suggested.     

黄鼠洞干蚤和宿主密度的年间动态关系

根据内蒙古自治区正镶白旗乌宁巴图苏木1981～1993年达乌尔黄鼠Citellus dauriCUS密度和洞干蚤指数监测资料进行分析,得到如下结果。共检洞干蚤9种,其中方形黄鼠蚤蒙古亚种Citellophilus tesquorum mongolicus (66.0%)为优势蚤种,光亮额蚤Frontopsylla lu-culenta(23.6%)为次优势蚤种,阿巴盖新蚤Neopsylla abagaitui和二齿新蚤N。Bidentatifor-mis为常见种,余为少见种。鼠密度与洞干蚤指数关系显著(PPP<0.05),关系为洞干蚤指数=0.2709+0.0504体蚤指数。洞干蚤和巢蚤指数的关系是显著的(P<0.07),关系为洞干蚤指数＝0.27652+0.00348巢蚤指数。三种蚤指数之间有如下近似 关系：巢蚤指数：体蚤指数：洞干蚤指数：100：10：1。     

Sampling fleas: the reliability of host infestation data

The use of measures of host infestation as a reliable indicator of a flea population size to be used in interspecific comparisons was considered. The abundance of fleas collected from host bodies and collected from host burrows was compared among 55 flea species, controlling for the effect of flea phylogeny. The mean number of fleas on host bodies correlated positively with the mean number of fleas in host burrows/nests both when the entire data pool was analysed and for separate subsets of data on 'fur' fleas and 'nest' fleas. This was also true for a within-host (Microtus californicus) between-flea comparison. The results of this study demonstrate that, in general, the index of host body infestation by fleas can be used reliably as an indicator of the entire population size.     

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°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.     

Trace fossils of the bivalve panopea faujasi,pliocene, Rhodes,Greece

The large bivalve, Panopea faujasi Ménard de la Groye, 1807 is locally abundant in shallow marine sandy facies in Late Pliocene sediments of Rhodes, where it occurs in life position within its burrow. Several Panopea‐trace fossils were sectioned in a vertical plane and others in series of horizontal sections, in order to study them in detail. Morphology of the structures produced by different individuals varied greatly, and even neighbors at the same horizon were unalike in detail. All show retrusive, upward shift in accordance with sedimentary accretion, but some also show protrusive movement as a response to erosive phases. As a response to sedimentation, the bivalve dug its way upwards by moving terrigenous grains and skeletal material from above it to below. In cross section the outline is slightly oval to circular. The longest example of these retrusive structures was preserved to a length of 86 cm and had a diameter of about 15 to 20 cm. As the bivalve has a long lifespan, and burrows deeply, the structures have good preservation potential and can reveal details of depositional history. The trace fossil is named Scalichnus phiale igen. et isp. nov.     

Burrowing behaviour of the European eel (Anguilla anguilla): Effects of life stage

The European eel (Anguilla anguilla) is a fascinating species, exhibiting a complex life cycle. The species is, however, listed as critically endangered on the IUCN Red List due to an amalgam of factors, including habitat loss. This study investigated the burrowing behaviour and substrate preference of glass, elver and yellow stages of A. anguilla. Preference was determined by introducing eels in aquaria with different substrates and evaluating the chosen substrate for burrowing. In addition, burrowing was recorded using a camera in all substrate types and analysed for kinematics. The experiments showed that all of these life stages sought refuge in the sediments with particle sizes ranging from sand to coarse gravel. Starting from a resting position, they shook their head horizontally in combination with rapid body undulations until half of their body was within the substrate. High-speed X-ray videography revealed that once partly in the sediment, eels used only horizontal head sweeps to penetrate further, without the use of their tail. Of the substrates tested, burrowing performance was highest in fine gravel (diameter 1–2 mm; lower burrowing duration, less body movements and/or lower frequency of movements), and all eels readily selected this substrate for burrowing. However, glass eels and elvers were able to use coarse gravel (diameter >8 mm) because their smaller size allowed manoeuvring through the spaces between the grains. Further, burrowing performance increased with body size: glass eels required more body undulations compared to yellow eels. Interestingly, the urge to hide within the sediment was highest for glass eels and elvers. Documentation of substrate preference and burrowing behaviour of A. anguilla provides new information about their potential habitat use. Considering that habitat alterations and deteriorations are partly responsible for the decline of the eel, this information can contribute to the development of more effective conservation measures.     

Co‐occupancy of spider‐engineered burrows within a grassland community changes temporally

Burrow‐digging organisms act as ecosystem engineers, providing potential habitat to other organisms. In the Mid North region of South Australia, wolf and trapdoor spiders in fragmented grassland communities provide this service. Pygmy bluetongue lizards are an endangered skink, endemic to these grasslands. The lizards obligatorily use burrows dug by these spider groups as refuges, basking sites and ambush points. We investigated the occupancy of these spider burrows by lizards and other organisms within the grassland community, identifying the occasions that burrows were shared by multiple taxa. We found that the lizards and trapdoor spiders are predominantly solitary, while wolf spiders co‐shared burrows more frequently with either weevils or snails. There were numerous taxa that were found to regularly co‐share with other taxa, particularly snails, centipedes and weevils. There was a strong temporal influence on burrow sharing, with most co‐sharing occurring late in summer. This study provides an insight into the use of burrows by the lizards and co‐existing taxa within these grassland communities. The dynamics of burrow‐use by other taxa have the potential to influence long‐term conservation of these lizards as burrow availability is crucial to their survival in these grasslands.