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Tiliqua adelaidensis 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Reptilia Squamata Scincidae

Scientific Name: Tiliqua adelaidensis (Peters, 1863)
Common Name(s):
English Pygmy Blue-tongue Lizard, Adelaide Pygmy Blue-tongue Skink, Pygmy Bluetongue, Pygmy Bluetongue Lizard
Synonym(s):
Cyclodus adelaidensis Peters, 1863

Assessment Information [top]

Red List Category & Criteria: Endangered B2ab(ii,iii,iv,v) ver 3.1
Year Published: 2018
Date Assessed: 2017-06-13
Assessor(s): Fenner, A., Hutchinson, M., McDonald, P. & Robertson, P.
Reviewer(s): Bowles, P.
Contributor(s): Harrison, N.
Facilitator/Compiler(s): Chanson, J.S.
Justification:
Listed as Endangered because its area of occupancy is less than 500 km2, it occurs as a severely fragmented population, and there is ongoing destruction of its habitat due to intensification of agriculture which is reducing the species' area of occupancy and destroyed or degraded its habitat, and has resulted in the documented loss of both mature individuals and subpopulations, declines which are ongoing. The species is dependent on continued land management, including both active conservation and the maintenance of traditional low-intensity grazing practices, to prevent its extinction.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Endemic to South Australia, this species' range presently extends from Peterborough south to Bagot Well. Historically the range extended south to Adelaide, from which it was lost in the 1950s (Wilson and Swan 2013, A. Fenner pers. comm. 2017).
Countries occurrence:
Native:
Australia (South Australia)
Additional data:
Estimated area of occupancy (AOO) - km2:499Continuing decline in area of occupancy (AOO):Yes
Estimated extent of occurrence (EOO) - km2:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:At localities where it still occurs this species can be quite common, but it is now restricted to very localized grassland remnants, and the population is considered severely fragmented as natural dispersal between subpopulations is impossible. In 2000 there were estimated to be around 5,000 individuals remaining, based on ten known populations; since then an additional 22 populations have been discovered (Duffy et al. 2012) and searches for new subpopulations are underway. None of the subpopulations occurs over an area of more than a few kilometres squared and some are as small as a few hectares, in some cases confined to paddocks with clear habitat boundaries (A. Fenner pers. comm. 2017). Several subpopulations have been lost: one small subpopulation was destroyed by a housing development, while two others experienced gradual declines and eventual extinction while monitoring was underway (A. Fenner pers. comm. 2017). One of these was lost in the absence of grazing or other pressure (A. Fenner pers. comm. 2017), and may simply reflect a remnant subpopulation too small to have been viable. A subpopulation in the Peterborough subject to annual monitoring may also have been lost from its core territory, as it has not recently been recorded from the main monitoring area, although a small number of animals have been found in the surrounding area (A. Fenner pers. comm. 2017). There is no current population estimate available.
Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Yes
Population severely fragmented:Yes
Continuing decline in subpopulations:Yes

Habitat and Ecology [top]

Habitat and Ecology:This species is thought to be restricted to highly modified treeless grasslands in grazing country (Wilson and Swan 2013). The mating system of this species has been proposed as "polygyny within stable non-social colonies" (Schofield et al. 2014).
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes

Use and Trade [top]

Use and Trade: This species is not legally available in the pet trade. While small numbers may be in illegal trade, it is not likely to be used or traded in any significant numbers (A. Fenner pers. comm. 2017).

Threats [top]

Major Threat(s): This species requires spider burrows in which to shelter, and the availability of these may be a limiting factor for remaining individuals (Souter et al. 2007, Nielson and Bull 2016). The species is therefore sensitive to any land use change that renders habitat unsuitable for large terrestrial spiders. The most important threat to the species is intensification of agriculture, and particularly the conversion of traditionally sheep-grazed land to cropland (A. Fenner pers. comm. 2017), which has resulted in significant fragmentation of the species's habitat. Pesticides and herbicides can affect their prey species. Land use changes resulting from infrastructure, including proposed dams, road building, drainage channels and wind farms, need to be managed to mitigate any impacts on the sites where this species survives, and at least one subpopulation has been lost to residential development (A. Fenner pers. comm. 2017).

Conservation Actions [top]

Conservation Actions: This species is listed as Endangered in both South Australia, under the National Parks and Wildlife Act 1972, and nationally under the Environment Protection and Biodiversity Act 1999 in Australia. It is found within a couple of small private protected areas, but there are no subpopulations found in any significant national or conservation parks. The species is wholly conservation-dependent: all known subpopulations require active land management with appropriate grazing regimes and without major changes to land use (such as switching from sheep grazing to cropping, vineyards, etc.) to ensure their survival. At present this mostly occurs as an incidental result of sheep grazing which maintains suitable habitat. Only be a single subpopulation, maintained as a reserve owned by the Nature Foundation SA, is known to be subject to formal management plans (A. Fenner pers. comm. 2017). This is a colonial species and any future reserves intended to benefit this species should ensure a sufficiently large population density is present or able to be maintained within the reserve (Schofield et al. 2014). The long term monitoring of certain subpopulations is underway, however there is room for further conservation actions to be conducted such as translocations and relocations (Duffy et al. 2012). A number of simulated translocations have been conducted to determine the best methodology for translocating this species and have found, for example, that additional days in confinement induce stress and hence any planned translocations or reintroductions should ensure as few days in confinement as possible before release (Ebrahimi and Bull 2014). Currently, there are translocation trials being conducted in the field to further refine the translocation and relocation process should individual subpopulations be exposed to elevated risk either through changes in land use or climate change.

Citation: Fenner, A., Hutchinson, M., McDonald, P. & Robertson, P. 2018. Tiliqua adelaidensis. The IUCN Red List of Threatened Species 2018: e.T21902A101743579. . Downloaded on 20 September 2018.
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