Biodiversity

Species Profile and Threats Database


For information to assist proponents in referral, environmental assessments and compliance issues, refer to the Policy Statements and Guidelines (where available), the Conservation Advice (where available) or the Listing Advice (where available).
 
In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.

EPBC Act Listing Status Listed as Endangered as Lucasium occultum
Listing and Conservation Advices Commonwealth Listing Advice on Diplodactylus occultus (Threatened Species Scientific Committee, 2006x) [Listing Advice].
 
Commonwealth Conservation Advice on Diplodactylus occultus (Threatened Species Scientific Committee, 2008xr) [Conservation Advice].
 
Recovery Plan Decision Recovery Plan not required, included on the Not Commenced List (1/11/2009).
 
Adopted/Made Recovery Plans
Policy Statements and Guidelines Survey guidelines for Australia's threatened reptiles. EPBC Act survey guidelines 6.6 (Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC), 2011m) [Admin Guideline].
 
Federal Register of
    Legislative Instruments
Inclusion of species in the list of threatened species under section 178 of the Environment Protection and Biodiversity Conservation Act 1999 (43) (14/08/2006) (Commonwealth of Australia, 2006g) [Legislative Instrument] as Diplodactylus occultus.
 
Amendment to the list of threatened species under section 178 of the Environment Protection and Biodiversity Conservation Act 1999 (95) (16/12/2009) (Commonwealth of Australia, 2009a) [Legislative Instrument] as Lucasium occultum.
 
State Government
    Documents and Websites
NT:Threatened Species of the Northern Territory- Yellow-snouted Gecko Diplodactylus occultus (Beggs, K., M. Armstrong, J. Woirnarski & S. Ward, 2012) [Information Sheet].
State Listing Status
NT: Listed as Vulnerable (Territory Parks and Wildlife Conservation Act 2000 (Northern Territory): 2012 list) as Diplodactylus occultus
Scientific name Lucasium occultum [82993]
Family Gekkonidae:Squamata:Reptilia:Chordata:Animalia
Species author (King, Braithwaite and Wombey, 1982)
Infraspecies author  
Reference Oliver, P. M., Hutchinson, M.N. & Cooper. S.J.B.(2007) Australian Journal of Zoology 55:197-210
Other names Diplodactylus occultus [1757]
Distribution map Species Distribution Map

This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.

Illustrations Google Images

Scientific name: Lucasium occultus

Common name: Yellow-snouted Gecko

Other names: Yellow-snouted Ground Gecko

The Yellow-snouted Gecko has been transferred to the genus Lucasium on phylogenetic grounds (Oliver et al. 2007). This classification is conventionally accepted (AFD 2007).

The Yellow-snouted Gecko is a small ground-dwelling gecko (snout-to-vent length 40 mm). The species is dark brown above, with a reddish head, four large, squarish pale brown blotches along the back, and whitish spots scattered on the flanks and limbs (DIPE 2006).

The Yellow-snouted Gecko is endemic to the Northern Territory and is known from only a few locations. Until the recent discovery of this species on Wildman Reserve, previous records were limited to only three specimens, all from the north-west of Kakadu National Park (King et al. 1982).

The extent of occurrence of the species (calculated as the minimum convex polygon containing all 17 records) is estimated to be 1283 km² ( DIPE 2006).

In August 2000, two individuals from Wildman Reserve were brought into captivity at the Territory Wildlife Park (Northern Territory). They produced 12 hatchlings in the 12 month period to March 2001 (DIPE 2002).

The range of the Yellow-snouted Gecko is limited and fragmented with populations only known from north-west Kakadu and Wildman Reserve (DIPE 2006).

The known range of the Yellow-snouted Gecko lies within the region with the highest intensity of fauna sampling in northern Australia. Sampling in the range of this species has included the following studies:

  • A baseline fauna inventory for the Alligator Rivers Fact-finding Study (CSIRO n.d.) was conducted in the 1970s, and included several years of intensive sampling by CSIRO across the range of habitats and geography of the Alligator Rivers Region. No Yellow-snouted Geckos were recorded.
  • The CSIRO Kakadu Fauna Survey of 1980–1983 sampled 30 sites (each with three subsites), selected to represent a range of lowland vegetation types. Each site was sampled (by recording species presence in pit-traps overnight) twice per year over a three-year period (Braithwaite 1985), for a total of 2880 nights. In addition, each site was spot-lit at least once on each of the six visits. Over the course of this study, three Yellow-snouted Geckos were recorded (King et al. 1982).
  • The Kakadu Stage III Fauna survey of 1988-1990 sampled the range of habitats across the southern one-third of Kakadu National Park (Woinarski & Braithwaite 1991). The total sampling effort for this survey was 370 sampling-sites, each with two pitfall-traps established over a 96-hour period, for a total of 2960 pit-trap nights; in addition each site was spotlit on two nights. No Yellow-snouted Geckos were recorded.
  • The Kapalga Fire experiment sampled reptiles (by pitfall trapping) in 16 sites, twice each year from 1988 to 1994, in forest and open woodlands exposed to a range of experimental fire regimes. From a total of about 4500 pit trap nights, one Yellow-snouted Gecko was captured (Andersen et al. 2003).
  • A specific short-term study of responses of reptiles to fire regimes at Kapalga, in 1992 sampled across a range of fire histories in lowland woodlands and open forests, with a total of 2700 trap-nights (Trainor & Woinarski 1994). IWhile 698 reptiles were captured, no Yellow-snouted Geckos were recorded.
  • A re-sampling of 263 of the 370 Stage III sites (see above) in 2001 (Watson & Woinarski 2003), for a total of 1638 pit-trap nights, found no Yellow-snouted Geckos.
  • A sampling of 114 permanent monitoring plots stratified across the range of terrestrial habitats in Kakadu National Park, over the period 1995 to 2004 (Watson & Woinarski 2004), for a total of 684 pit-trap nights, recorded no Yellow-snouted Geckos.
  • An intensive survey of the Mary River catchment (to the immediate west of Kakadu National Park) over 18 months in 1988–1989, at 152 sites stratified to represent the range of terrestrial habitats and geographic spread, for a total of 1824 pit-trap nights (Armstrong et al. 2002), found no Yellow-snouted Geckos.
  • A three-year study (1999–2002) of the impacts of exotic pasture grasses on biodiversity was conducted in the Wildman and Mary River catchments (Beggs 2009). This survey included 24 woodland sites, sampled four times each, with each sample including 30 pit-trap nights (a total of 2880 pit-trap nights). Four Yellow-snouted Geckos were recorded.
  • Ongoing monitoring of vertebrate fauna at Mt Bundy Training Area (to the immediate west of Kakadu National Park, and immediately south of the previous study), at 12 main study sites, each sampled twice in 1989 and 2002 with six pitfall traps in place over a 72-hour period (Corbett 2002), for a total of 864 pit-trap nights. No Yellow-snouted Geckos were recorded. However one Yellow-snouted Gecko was recorded from the Mt Bundy Training Area in 2004 in repeat surveying of the area (P Horner, pers. comm. in Beggs et al. 2006).
  • In specific sampling in 2004 (36 pit-trap nights) for the Yellow-snouted Gecko at sites on Wildman Reserve, in which the species had previously been recorded, only one Yellow-snouted Gecko was recorded.

There has been other sampling of vertebrate fauna in the general area (circumscribed by and around the known records), such as for environmental impact statements, and as part of other broader studies (for example, Woinarski et al. 1999), but these have produced no other records of the species. Such studies have probably included about 500 pit-trap nights.

In addition to these formal studies, the area of occupancy of this species has been frequently visited by many resident and visiting naturalists, including by Kakadu staff. However, no Yellow-snouted Gecko sightings have been recorded.

Only 10 individual Yellow-snouted Gecko have been reported, from a total of about 22 000 trap-nights (DIPE 2006). None of these studies has involved mark and recapture, so no definitive population estimate is possible. Given the very low frequency of captures for a species that should be easily trapped, it is probable that the species occurs at very low population density. Its geographic range also appears highly circumscribed. Its total population would appear to be low.

Both known populations of the Yellow-snouted Gecko occur within reserves; Kakadu National Park and Wildman Reserve (DIPE 2006).

Very little is known of the ecology of the Yellow-snouted Gecko. All individuals captured to date have occurred in conjunction with well-developed leaf litter and grasses (King et al. 1982) in open forests dominated by Eucalyptus miniata and E. tetrodonta. Records from Wildman Reserve include sites with sparse to moderate occurrences of introduced gamba grass (Andropogon gayanus).

As for all terrestrial Diplodactylus geckos, pitfall trapping is the most appropriate sampling technique for this species (DIPE 2006).

The Yellow-snouted Gecko appears to be restricted to lowland open forests in the adjoining Mary, Wildman and West Alligator catchments. Fire regimes in this environment and this region have been the subject of a series of recent studies. These have concluded that the current regime is different from the historic regime, and is now characterised by an increased extent of fires and more intense fires resulting from a higher frequency of fires in the late dry season (Andersen et al. 1998, 2003). The current fire regime is regarded as being too frequent for the Yellow-snouted Gecko (Andersen et al. 2005; Pardon et al. 2003; Woinarski 2004; Woinarski et al. 2004).

Compounding this change in burning practices, the Wildman and Mary River catchments have been extensively invaded by exotic pasture grasses, particularly Gamba (Andropogon gayanus) and Mission (Pennisetum polystachion) grasses. These grasses are also increasing within Kakadu National Park. Studies of these exotic grasses in open forests in Wildman Reserve suggest that fuel loads are increased three to five times, and fire intensities eight-fold, relative to comparable open forests with native grasses (Rossiter et al. 2003). These hotter fires are likely to increase the mortality of terrestrial geckos and their eggs, reduce the leaf litter in which they shelter, and increase predation risks.A study by Beggs (2009) has also found a significant negative association between the Yellow-snouted Gecko and the level of gamba grass cover in the Mary River Catchment area.

The Threatened Species Scientific Committee (2006x, 2006as) has prepared listing and conservation advice for the Yellow-snouted Gecko. There is no existing management program for the Yellow-snouted Gecko in the Northern Territory.

Recommended research priorities include undertaking further survey work and baseline ecological research aimed at establishing the distribution, abundance and ecological requirements of the Yellow-snouted Gecko.

Until more is known about the ecological requirements of this species, its population size and the threats operating, management priorities cannot be described with any confidence (DIPE 2006).

The following projects have received Government funding grants for conservation and recovery work benefiting the Yellow-snouted Gecko:

The Threatened Species Network Community Grants released $6273 of funding in 2007–08 to manage and monitor the Yellow-snouted Gecko on the three sites that are currently known, all on privately managed land, in collaboration with the lease manager. This will involve creating fire breaks, establishing long-term monitoring plots, and raising awareness amongst the broader community of the impacts of contemporary fire regimes on this species and broader biodiversity.

King and colleagues (1982) provide the most comprehensive description of the Yellow-snouted Gecko.

The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.

Threat Class Threatening Species References
Ecosystem/Community Stresses:Indirect Ecosystem Effects:Restricted geographical distribution (area of occupancy and extent of occurrence) Commonwealth Listing Advice on Diplodactylus occultus (Threatened Species Scientific Committee, 2006x) [Listing Advice].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation Pennisetum polystachion (Mission Grass, Perennial Mission Grass, Missiongrass, Feathery Pennisetum, Feather Pennisetum, Thin Napier Grass, West Indian Pennisetum, Blue Buffel Grass) Commonwealth Conservation Advice on Diplodactylus occultus (Threatened Species Scientific Committee, 2008xr) [Conservation Advice].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation by weeds Commonwealth Conservation Advice on Diplodactylus occultus (Threatened Species Scientific Committee, 2008xr) [Conservation Advice].
Natural System Modifications:Fire and Fire Suppression:Inappropriate and/or changed fire regimes (frequency, timing, intensity) Commonwealth Conservation Advice on Diplodactylus occultus (Threatened Species Scientific Committee, 2008xr) [Conservation Advice].
Species Stresses:Indirect Species Effects:Low numbers of individuals Commonwealth Listing Advice on Diplodactylus occultus (Threatened Species Scientific Committee, 2006x) [Listing Advice].

Commonwealth Scientific Investigation & Research Organisation (CSIRO) ((n.d.)). Wildlife. Alligator Rivers Region Environmental Fact-finding Study. Canberra: CSIRO.

Andersen, A.N., G.D. Cook & Williams R.J., eds. (2003). Fire in Tropical Savannas: The Kapalga Fire Experiment. New York: Springer-Verlag.

Andersen, A.N., G.D. Cook, L.K. Corbett, M.M. Douglas, R.W. Eager, J. Russell-Smith, S.A. Setterfield, R.J. Williams & J.C.Z. Woinarski (2005). Fire frequency and biodiversity conservation in Australian tropical savannas: implications from the Kapalga fire experiment. Australian Journal of Ecology. 30:155-167.

Andersen, A.N., R.W. Braithwaite, G.D. Cook, L.C. Corbett, R.J. Williams, M. Douglas, A.M. Gill, S. Setterfield & W.J. Muller (1998). Fire research for conservation management in tropical savannas: introducing the Kapalga fire experiment. Australian Journal of Ecology. 23:95-110.

Armstrong, M., J. Woinarski, C. Hempel, G. Connors & K. Beggs (2002). A Plan for the Conservation of Biodiversity in the Mary River Catchment, Northern Territory. Darwin: Parks and Wildlife, Department of Infrastructure, Planning and Environment.

Australian Faunal Directory (AFD) (2007). Australian Faunal Directory. [Online]. Available from: http://www.environment.gov.au/biodiversity/abrs/online-resources/fauna/afd/index.html.

Beggs, K (2009). Effects of exotic pasture grasses on biodiversity in the Mary River catchment, Northern Territory. PhD Thesis. Ph.D. Thesis. Darwin: Institute of Advanced Studies, Charles Darwin University.

Beggs, K., M. Armstrong & J. Woirnarski (2006). Threatened Species of the Northern Territory- Yellow-snouted Gecko Diplodactylus occultus. [Online]. Darwin: Department of Natural Resources, Environment and the Arts, Northern Territory. Available from: http://www.nt.gov.au/nreta/wildlife/animals/threatened/pdf/herps/yellowsnouted_gecko_vu.pdf.

Braithwaite, R.W. (1985). The Kakadu fauna survey: an ecological survey of Kakadu National Park. Canberra: Australian National Parks & Wildlife Service.

Cogger, H.G. (2000). Reptiles and Amphibians of Australia - 6th edition. Sydney, NSW: Reed New Holland.

Corbett, L.K. (2002). Fauna survey (pre-Cane Toad) at Mount Bundy Training Area. Report to Department of Defence. Darwin: IT Environmental.

Department of Infrastructure, Planning and Environment, Northern Territory. (DIPE) (2002). Department of Infrastructure, Planning and Environment 2001-2002 Annual Report. Darwin: Department of Infrastructure, Planning and Environment.

DIPE (Department of Infrastructure, Planning and Environment) (2006). Biodiversity Conservation, Northern Territory Government.

King, M., R.W. Braithwaite & J.C. Wombey (1982). A new species of Diplodactylus (Reptilia: Gekkonidae) from the Alligator Rivers region, Northern Territory. Transactions of the Royal Society of South Australia. 106:15-18.

Oliver, P.M., Hutchinson, M.N. & Cooper, S.J.B. (2007). Phylogenetic relationships in the lizard genus Diplodactylus Gray and resurrection of Lucasium Wermuth (Gekkota, Diplodactylidae). Australian Journal of Zoology. 55:197-210.

Pardon, L.G., B.W. Brook, A.D. Griffiths & R.W. Braithwaite (2003). Determinants of survival for the Northern Brown Bandicoot under a landscape-scale fire experiment. Journal of Animal Ecology. 72:106-115.

Rossiter, N.A., S.A. Setterfield, M.M. Douglas & L.B. Hutley (2003). Testing the grass-fire cycle: alien grass invasion in the tropical savannas of northern Australia. Diversity and Distributions. 9:169-176.

Sinclair Knight Merz Pty Ltd (SKM) (2008). Listed threatened fauna species on military land in Northern Australia.

Threatened Species Scientific Committee (2006x). Commonwealth Listing Advice on Diplodactylus occultus. [Online]. Available from: http://www.environment.gov.au/biodiversity/threatened/species/diplodactylus-occultus.html.

Trainor, C.R. & J.C.Z. Woinarski (1994). Responses of lizards to three experimental fires in the savanna forests of Kakadu National Park. Wildlife Research. 21:131-48.

Watson, M. & J. Woinarski (2003). Vertebrate monitoring and resampling in Kakadu National Park, 2002. Report to Parks Australia North. Page(s) 2002. Darwin: Parks and Wildlife Commission of the Northern Territory.

Watson, M. & J. Woinarski (2004). Vertebrate monitoring and resampling in Kakadu National Park, 2003. Report to Parks Australia North. Darwin: Parks and Wildlife Commission of the Northern Territory.

Woinarski, J.C.Z. (2004). The forest fauna of the Northern Territory: knowledge, conservation and management. In: Lunney,D., ed. Conservation of Australia's Forest Fauna (second edition).

Woinarski, J.C.Z. & R.W. Braithwaite (1991). Wildlife of Kakadu Stage III: a synthesis. Report to ANPWS. Darwin: CSIRO.

Woinarski, J.C.Z., Gambold, N., Wurst, D., Flannery, T.F., Smith, A.P., Chatto, R. & Fisher, A. (1999). Distribution and habitat of the northern hopping-mouse, Notomys aquilo. Wildlife Research. 26:495-511.

Woinarski, J.C.Z., J. Risler & L. Kean (2004). The response of vegetation and vertebrate fauna to 23 years of fire exclusion in a tropical Eucalyptus open forest, Northern Territory, Australia. Australian Ecology. 29:156-176.

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This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.

Citation: Department of the Environment (2014). Lucasium occultum in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Thu, 31 Jul 2014 10:40:01 +1000.