Pygmy Bluetongue Lizard Tiliqua Adelaidensis Research Articles

Editorial for the Michael Bull special issue

A review of the role of parasites in the ecology of reptiles and amphibiansParasite in peril? A new species of mite in the genus Ophiomegistus Banks (Parasitiformes: Paramegistidae) on an endangered host, the pygmy bluetongue lizard Tiliqua adelaidensis (Peters) (Squamata: Scincidae)

The impact of sheep grazing on burrows for pygmy bluetongue lizards and on burrow digging spiders

AbstractGrazing by domestic stock has altered and degraded natural grassland ecosystems worldwide, directly and indirectly impacting the endemic plant and animal species occupying those grasslands. The pygmy bluetongue lizard Tiliqua adelaidensis is an endangered species, restricted now to fragments of native grassland habitat in South Australia, which are predominantly grazed by sheep. These lizards exclusively occupy burrows dug by spiders, and use them as refuges, basking sites and ambush points. They do not dig their own burrows and rely on coexisting spiders for this essential resource. We asked how sheep grazing influences construction and persistence of spider burrows by comparing burrow dynamics in adjacent grazed and ungrazed grassland habitats. In ungrazed plots, spider burrows increased over one spring and summer period, particularly after a summer rain event that softened the soil. In grazed plots, more existing burrows were destroyed, presumably by sheep trampling, and fewer new burrows were constructed, leading to a net loss in burrow numbers over the same period. However, in this short study, grazing did not affect the number of pygmy bluetongue lizards or the number of lycosid spiders. Burrows that were lost tended to be shallower and to have smaller diameter entrances than those that were retained, suggesting that the best burrows for lizard refuges were more likely to persist despite sheep activity. However, heavy grazing may have negative impacts on both lizards and spiders, resulting from a reduction in available burrows and in spider digging behaviour.

Determining the success of varying short-term confinement time during simulated translocations of the endangered pygmy bluetongue lizard (Tiliqua adelaidensis)

Translocation is a powerful tool in conservation management, but one of the major problems of this tool is dispersal after release. Translocated animals might disperse from prime habitat and face unsuitable habitat and possible increased exposure to predators. This might lead to decline of a translocated population and could compromise the success of translocation. We assessed whether short-term confinement within enclosures at the translocation site can significantly decrease post release movement, if confinement allowed animals to become familiar with the new habitat, and to overcome handling related stress. We simulated the translocation of an Australian lizard, the endangered pygmy bluetongue lizard Tiliqua adelaidensis, into the centre of a large enclosure and compared the behaviour between individuals confined to the central region for one or five days before release. We found that lizards confined for five days spent less time basking, and were more likely to disperse than lizards confined for just one day. We suggest that short-term confinement of lizards induces additional stress and that extra days of short-term confinement will not necessarily improve the success of a translocation. Future research could determine the effectiveness of different durations of confinement for releasing animals at translocation sites.

Food supplementation reduces post-release dispersal during simulated translocation of the Endangered pygmy bluetongue lizard Tiliqua adelaidensis

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 18:169-178 (2012) - DOI: https://doi.org/10.3354/esr00446 Food supplementation reduces post-release dispersal during simulated translocation of the Endangered pygmy bluetongue lizard Tiliqua adelaidensis Mehregan Ebrahimi*, C. Michael Bull School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001, Australia *Email: mehregan.ebrahimi@gmail.com ABSTRACT: Translocation is among several tools available to conservation managers, either to augment existing populations, or to establish populations in previously occupied habitat, or in habitat identified as suitable for the future persistence of the species. Translocated reptiles do not always become established at the release site. We simulated a translocation site for an Endangered Australian skink, the pygmy bluetongue lizard Tiliqua adelaidensis, to investigate whether adding food would encourage released individuals to disperse less. We provided artificial burrows in a central release area within circular cages and found that lizards were more likely to remain in a burrow, spent less time exposed on the ground surface and were less likely to move out of the central area when food was provided. These modified behaviours are likely to encourage translocation success if lizards with added food expose themselves less frequently to predators, and if fewer of those lizards disperse away from the translocation site in the early days after release. We suggest that the provision of supplementary food will be an important component of any translocation programme for this lizard. KEY WORDS: Supplementary food · Translocation · Tiliqua adelaidensis · Conservation Full text in pdf format PreviousNextCite this article as: Ebrahimi M, Bull CM (2012) Food supplementation reduces post-release dispersal during simulated translocation of the Endangered pygmy bluetongue lizard Tiliqua adelaidensis . Endang Species Res 18:169-178. https://doi.org/10.3354/esr00446 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 18, No. 2. Online publication date: August 16, 2012 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2012 Inter-Research.

The impact of heavy grazing on burrow choice in the pygmy bluetongue lizard, Tiliqua adelaidensis

Context Grazing pressure has directly altered and indirectly influenced natural ecosystems worldwide, and has affected and displaced many native species. The endangered pygmy bluetongue lizard Tiliqua adelaidensis is endemic to the mid-north of South Australia. It inhabits remnant native grasslands where it is reliant on the presence of natural spider burrows constructed by lycosid and mygalomorph spiders as refuge sites. These lizards spend the majority of the day associated with their burrow either in the burrow itself or basking at its entrance. The remnant native grasslands of South Australia have endured 200 years of agricultural changes and the introduction of domestic stock has meant that grazing pressure has substantially increased. The vegetation around a burrow is considered to be important in providing shelter for the lizard. However, too much vegetation may reduce basking opportunities and visibility of prey. Stock grazing has been maintained on the majority of sites that contain pygmy bluetongue populations and it is presumed that the lizards can tolerate some form of grazing. However, the level of grazing intensity directly influences the vegetation structure that surrounds the lizard burrows. Aims We aimed to investigate the consequences of severe grazing pressure on the choice of burrows by lizards, and on their burrow related behaviour. Methods We simulated heavy grazing pressure by manually removing aboveground vegetation in the field in replicated quadrats that contained artificial burrows, and by providing bare substrate in half of experimental enclosures in the laboratory. Key results In the field, lizards only occupied the artificial burrows in control quadrats, where vegetation had been left intact. In the laboratory, lizards that occupied both burrows basked for longer at the burrow entrance where vegetation was present. Conclusions Heavy grazing management that results in the majority of vegetation being removed could have a negative impact on pygmy bluetongue lizard recruitment and sustainability. Implications Grazing regimes should be carefully monitored to consider the needs of species that rely heavily on microhabitat structure for their persistence. For the endangered pygmy bluetongue lizard, heavy grazing should be avoided to promote amounts of vegetation suitable to sustain viable populations.

Central‐place territorial defence in a burrow‐dwelling skink: aggressive responses to conspecific models in pygmy bluetongue lizards

In central-place territorial systems, individuals usually defend a central home site or refuge from conspecifics. Visual communication among individuals is crucial for social organization, provides information on current circumstances and allows assessment of conspecific intruders from a safe distance. We examined the role of visual cues in eliciting territorial defence behaviour in the endangered Australian pygmy bluetongue lizard Tiliqua adelaidensis. In field conditions, lizards discriminated between models of a conspecific and a similar-sized non-conspecific lizard. They displayed the highest level of aggression towards the conspecific model placed 5 cm from their burrow entrance. Male and female lizards displayed the same level of aggression and maintained an equivalent level of aggression throughout their activity season. Lizards showed less aggression towards models moved a further 10 cm from the burrow entrance. These results indicate that pygmy bluetongue lizards use visual cues in their social interactions and appear to display a central-place territorial defence social system. We interpret the distance effect as a reluctance to leave their burrow unattended because takeovers are easier if the resident is away from the burrow.

Spiders provide important resources for an endangered lizard

AbstractConservation management requires knowledge of how a target species interacts with other species. Some relatively common species can modify the environment to the advantage of rarer, endangered species. Thus, local enhancement of those common species can positively influence remaining populations of the rarer species. The endangered pygmy bluetongue lizard Tiliqua adelaidensis inhabits burrows that are constructed by lycosid and mygalomorph spiders. We recorded 490 burrows in a 1 ha plot at the end of one season, and then observed at regular intervals the formation and loss of burrows, and the changes in occupancy status of each burrow over the next season. We found spiders in 94% of all newly constructed burrows and deduced that they had built the burrows. We found no evidence that lizards dug new burrows or deepened existing burrows. The numbers of both lizards and spiders in the burrows declined over the spring and summer, with lizards moving from their burrows more often early in the season than later. However, there was no strong trend for lizards to replace spiders in burrows. In fact, lizards tended to occupy deeper burrows than spiders, suggesting little negative impact of lizards on spiders. However, spiders had a positive impact on lizards by providing the refuge burrows central for lizard survival. Although lizards readily accept artificial burrows, long‐term conservation for the lizards must include viable spider populations to maintain a supply of suitable burrow refuges.

Pharyngodon wandillahensis n. sp. (Nematoda: Pharyngodonidae) from the Endangered Pygmy Bluetongue Lizard Tiliqua adelaidensis Peters, 1863 (Sauria: Scincidae), South Australia, Australia

Pharyngodon wandillahensis n. sp. from the endangered pygmy bluetongue lizard Tiliqua adelaidensis Peters, 1863, from the midnorth of South Australia, Australia is described and illustrated. Pharyngodon wandillahensis n. sp. represents the thirty-seventh species assigned to Pharyngodon. It is distinguished from the 5 other Australian species by its smaller size, the form of the lateral alae, and in having 6 small but fleshy lips. Prevalence, distribution and intensity in the host T. adelaidensis are also reported.

Short‐term impact of grassland fire on the endangered pygmy bluetongue lizard

AbstractWildfires may be beneficial to overall biodiversity in continuous habitat, but may have more severe impacts on individual species that are confined to small fragments of suitable habitat. The pygmy bluetongue lizard Tiliqua adelaidensis, is now confined to a few isolated fragments of previously extensive native grasslands in South Australia. A grassland fire that burned through the entire area of one population in December 2005 did not kill adult lizards, nor affect the subsequent fecundity of females, but was followed by significant reductions in activity and foraging and a decline in body condition relative to another population in an unburned site. While the study was not, and should not be replicated, our observations suggest that fire has a negative short‐term impact on isolated populations of this species.

Habitat Requirements and Conservation of the Endangered Pygmy Bluetongue Lizard Tiliqua Adelaidensis: Ph.D. Summary

Habitat Requirements and Conservation of the Endangered Pygmy Bluetongue Lizard Tiliqua Adelaidensis: Ph.D. Summary

Parasite loads in parthenogenetic and sexual lizards (Heteronotia binoei) : support for the Red Queen hypothesis

One version of the Red Queen hypothesis suggests that sexual reproduction is maintained in populations because of the need to continually create genotypes that confer resistance against rapidly evolving pathogens and parasites. Here, we report that parthenogenetic individuals of the Heteronotia binoei species complex are much more prone to infection by mites than are their sexual relatives. This accords with a central prediction of the Red Queen hypothesis. The greater susceptibility of the parthenogens is consistent across localities with different combinations of parthenogenetic genotypes and sexual chromosome races and occurs despite the unusually high genetic diversity of the parthenogenetic form. These observations support the contention that clonal reproduction increases the susceptibility of hosts to infection by parasites.