Threatened Species Nomination Form

Invitation to comment on EPBC Act nomination to list in the critically endangered category: Cryptoblepharus egeriae (blue-tailed skink)

Anyone may nominate a native species, ecological community or threatening process for listing under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).

You are invited to provide comment on the attached nomination to assist the Threatened Species Scientific Committee (the Committee) with its assessment of whether Cryptoblepharus egeriae (blue-tailed skink) is eligible for inclusion in the EPBC Act list of threatened species in the critically endangered category.

The Committee welcomes the views of experts, stakeholders and the general public on nominations to further inform its nomination assessment process. In order to determine if a species, ecological community or threatening process is eligible for listing under the EPBC Act, a rigorous scientific assessment of its status is undertaken. These assessments are undertaken by the Committee to determine if an item is eligible for listing against a set of criteria as set out in the guidelines for nominating and assessing threatened species and ecological communities, and threatening processes. These are available at: http://www.environment.gov.au/biodiversity/threatened/nominations.html To assist in this matter, the Committee has identified a series of specific questions on which it seeks particular guidance (Part A). The nomination for this item is provided in Part B. Individual nominations may vary considerably in quality. Therefore in addition to the information presented in the nomination, the Committee also takes into account published data and considers other information received when it prepares its advice for the Minister. Responses to this consultation will be provided in full to the Minister for Sustainability, Environment, Water, Population and Communities. In providing comments, please provide references to published data where possible. Should the Committee use the information you provide in formulating its advice, the information will be attributed to you and referenced as ‘personal communication’ unless you provide references or otherwise attribute this information. The Committee’s advice may be published on the department’s website at completion of the assessment and decision by the Minister. Information provided through consultation may be subject to freedom of information legislation and court processes. It is also important to note that under the EPBC Act, the deliberations and recommendations of the Committee are confidential until the Minister has made a final decision on the nomination, unless otherwise determined by the Minister. The views expressed within the attached nomination (Part B) do not necessarily reflect the opinions of the Australian Government. The Australian Government and the Committee do not accept responsibility for the accuracy or completeness of the contents of the nomination. Included here for your consideration of the nomination are: Part A – specific questions identified by the Committee Part B – nomination information

PART A

Questions relating to Cryptoblepharus egeriae (Blue-tailed skink – Christmas Island)

1. Can you comment on whether or not there is sufficient evidence that this entity is a distinct species? 2. Do you consider the way the population size has been estimated to be appropriate and do you accept the estimate of the total population size of the species? If not, can you provide an estimate of the range of population size? 3. Are you aware of any additional evidence which shows the population is, increasing or declining? If evidence is available, could you provide a range for the rate of change for the species? 4. Do you consider the current distribution of the species, as described in the nomination, to be valid? If not, why? 5. Do you consider that the way the past and current extent of occurrence/area of occupancy has been estimated is appropriate? If not, why? 6. Do you know of any past, current or potential threats that may adversely affect this species at any stage of its life cycle? 7. Can you provide additional data or information relevant to this assessment? 8. Have you been involved in developing this nomination? If so, in what capacity? 9. Do you agree with the proposal to list this species? Please summarise your reasoning

PART B Section 1 - Legal Status, Distribution, Biological, Ecological

Conservation Theme 1. Not applicable - there is no N/A conservation theme for the 2011 assessment period.

Taxonomy 2. What are the currently blue-tailed skink Cryptoblepharus egeriae (Boulenger, accepted scientific and common 1889) name/s for the species (please include Indigenous names, where Order: Squamata. Family: Scincidae known)? Note any other scientific names that have been used recently. Note the species authority and the Order and Family to which the species belongs (Family name alone is sufficient for plants, however, both Order and Family name are required for insects). 3. Is this species conventionally The species is conventionally recognised, with this accepted? If not, explain why. Is taxonomy well established, including in a recent review of there any controversy about the the taxonomy of the genus Cryptoblepharus (Horner taxonomy? 2007). 4. If the species is NOT n/a conventionally accepted, please provide: (i) a taxonomic description of the species in a form suitable for publication in conventional scientific literature; OR (ii) evidence that a scientific institution has a specimen of the species and a written statement signed by a person who has relevant taxonomic expertise (has worked, or is a published author, on the class of species nominated), that the person thinks the species is a new species. 5. Is this species taxonomically No particular taxonomic distinctiveness – the genus distinct (Taxonomic distinctiveness Cryptoblepharus is speciose. – a measure of how unique a species is relative to other species)?

Legal Status 6. What is the species’ current This species occurs only on the Australian external territory conservation status under of Christmas Island. It is not listed as threatened in any Australian and State/Territory Australian jurisdiction. Government legislation? 7. Does the species have specific The distribution of the species is restricted to Christmas protection (e.g. listed on an annex Island, mostly (63%) included within a national park, or appendix) under other legislation where it is protected. Under EPBC Act regulations, it is or intergovernmental also afforded some protection in those parts of Christmas arrangements, e.g. Convention on Island outside the Park area. International Trade in Endangered It is not listed as threatened under CITES, CMS or by the Fauna and Flora (CITES), IUCN. Convention on Migratory Species (CMS).

PART A Description 8. Give a brief description of the The blue-tailed skink is a small (snout-vent length 4-5 cm) species’ appearance, including size slender skink, whose most conspicuous feature is a bright and/or weight, and sex and age light blue tail colouration. It forages on the ground, rocks, variation if appropriate; social and in low vegetation. It has been observed high on tree structure and dispersion (e.g. trunks and may forage in the canopy, while it is also found solitary/clumped/flocks). on the limestone cliff walls that form much of the Island’s shoreline. It occurs singly or in small groups.

9. Give a brief description of the The blue-tailed skink is a generalist predator of small species’ ecological role (for invertebrates; and is unlikely to play a major ecological example, is it a ‘keystone’ or role. ‘foundation’ species, does it play a role in processes such as seed dispersal or pollination).

Australian Distribution 10. Describe the species’ current The blue-tailed skink is endemic to the 135 km2 Christmas and past distribution in the Island. Historic records (Andrews 1901; Gibson-Hill 1947) Australian distribution and, if report that it was once common and widespread. Reptile available, attach a maps noting the surveys in 1979 recorded it as “one of the most source and the datasets used to conspicuous and abundant reptiles on Christmas Island” create these. (xxxx xxxx; Cogger et al. 1983). However it has subsequently declined drastically in numbers and range. By 1992, it had declined appreciably in the settlement area (Rumpff 1992; xxxx), and thereafter it declined (or disappeared) sequentially across all other habitats on the Island. xxxx (xxxx) re-sampled reptiles on Christmas Island in 1998: they confirmed its absence from the settlement area (where it was abundant in 1979) and concluded that it had “suffered a significant contraction in range from the north-east, where it was previously present in large numbers, implying that there had been a decline in total numbers. However it still occurs in lower densities throughout most of the central and western parts of the island and probably around most parts of the coastal perimeter.”

By 2004, James (2004) reported that “the Blue-tailed skink has declined severely. It was recorded during seven quantitative surveys. It now appears to be confined to scattered, localised pockets in remote areas of the coastal terraces.” Intensive and extensive surveys by Schulz and Barker in 2008 (including sampling at 68 sites across the Island) resulted in this species being recorded from only two areas (Egeria Point and North West Point).

Subsequent surveys by Parks Australia staff have confirmed its disappearance from the North West Point site (in mid 2008) and suggest disappearance from Egeria Point (in mid 2010) [xxxx unpubl. data.].

It is now uncertain whether it persists in the wild. Notwithstanding ongoing extensive structured biodiversity sampling across the Island, and additional targeted searches for this species, with the disappearance of the Egeria Point population, no populations are now known in

PART A the wild.

11. What is the extent of occurrence (in km2) for the species (described in Attachment A); explain how it was calculated and provide information on data sources. a. What is the current extent of The current extent of occurrence is uncertain, but most occurrence? likely to be < 100 ha. Parks Australia officers currently responsible for survey and management of the species suggest that (if it persists in the wild) EOO is < 1 ha (xxxx). b. What data are there to indicate The former EOO was 135 km2; its range contraction started past declines in extent of from about the late 1980s or early 1990s (i.e. decline of occurrence (if available, include data that indicates the 95-100% of range over a period of about 20 years). percentage decline over the Variation in the rate of decline over this period is unknown, past 10 years or 3 generations but it is likely to have been constant or to have whichever is longer)? accelerated, suggesting that the decline over the time period relevant to this assessment (three generations=9- 12 years) is at least 50% of its original distribution, or 95- 100% of its 2001 distribution. c. What data are there to indicate No information available. It may not persist in the wild. future changes in extent of occurrence (if available, include data that indicates the percentage decline over 10 years or 3 generations whichever is longer (up to a maximum of 100 years in the future) where the time period is a continuous period that may include a component of the past)? 12. What is the area of The current area of occupancy is uncertain, but most likely occupancy (in km2) for the species to be < 100 ha. (described in Attachment A); explain how it was calculated and provide information on data sources a. What is the current area of As for EOO. occupancy? b. What data are there to indicate As for EOO. past declines in area of occupancy (if available, include data that indicates the percentage decline over the past 10 years or 3 generations whichever is longer)? c. What data are there to indicate As for EOO. future changes in area of occupancy (if available, include data that indicates the percentage decline over 10 years or 3 generations whichever is longer (up to a maximum of 100 years in the future) where the time period is a continuous period that may include a component of the past)? 13. How many natural locations No extant populations in the wild are known. The last do you consider the species occurs known population was at Egeria Point, on the Island’s in and why? Where are these extreme SW tip (10°30’54.1”S 105°32’32.5”E: Map datum: located? Provide latitude, longitude, WGS 1984).

PART A map datum and location name, where available, in an attached table. The term 'location' defines a geographically or ecologically distinct area. 14. Give locations of other Since 2009, a captive breeding population has been populations: captive/propagated established in holding cages at Christmas Island, with populations; populations recently recent (2011) establishment of additional captive breeding re-introduced to the wild; and sites populations (from these stock) at Taronga Park. The for proposed population re- number of individuals in these captive breeding populations introductions. Note if these sites is over 160 (on Christmas Island and at Taronga Zoo - at have been identified in recovery November 2011). plans. Provide latitude, longitude, map datum and location name, where available, in an attached table. 15. Is the species’ distribution No extant populations in the wild are known. The decline severely fragmented? What is the occurred incrementally, with some isolated populations cause of this fragmentation? persisting marginally longer than others. Describe any biological, geographic, human-induced or other barriers causing this species’ populations to be fragmented. Severely fragmented refers to the situation in which increased extinction risk to the taxon results from most individuals being found in small and relatively isolated subpopulations (in certain circumstances this may be inferred from habitat information). These small subpopulations may go extinct, with a reduced probability of recolonisation. 16. Departmental Use Only:

Global Distribution 17. Describe the species’ global The blue-tailed skink is restricted to Christmas Island distribution. (Indian Ocean). 18. Give an overview of the global population’s size, trends, threats and security of the species outside Australia. 19. Explain the relationship between the Australian population and the global population, including: a. What percentage of the global population occurs in Australia; b. Is the Australian population distinct, geographically separate or does part or all of the population move in/out of Australia’s jurisdiction (give an overview; details in Movements section); c. Do global threats affect the Australian population?

Surveys and Monitoring 20. Has the species been The blue-tailed skink has been the subject of a substantial reasonably well surveyed? amount of survey and monitoring. In 1979 and again in Provide an overview of surveys to date

PART A and the likelihood of the species’ its 1998, Cogger and Sadlier undertook an extensive sampling current known distribution and/or of all reptile species on Christmas Island. Subsequently, population size being its actual distribution and/or population size. this (and other reptile) species have been included in the Include references documenting the Island’s detailed Biodiversity Monitoring program (BMP) current known distribution and location (2003-06) (James 2004, 2005), and the “Island-wide records and survey methodology where Survey” (IWS) (from 2001 to 2011 – although reptile available. species were not targeted in sampling until the 2009 IWS).

The BMP included over 320 quantitative searches for reptiles at sites “covering the entire island”; “quantitative searches involved two to three people searching an area of forest by raking the leaf litter, rolling and splitting fallen logs, and stripping bark off fallen and standing trees. Searches were timed (average 20 min.) and generally covered about 0.5 ha. A total observer effort of 262 hours 40 mins was put into the surveys.” (James 2004).

The IWS includes sampling at 900 points (for this species and a range of other biodiversity), equally spaced across the extent of the Island.

This (and other reptile) species has also been the subject of a specific survey in 2008 focusing on conservation status (Schulz and Barker 2008). 21. For species nominated as extinct or extinct in the wild, please provide details of the most recent known collection, or authenticated sighting of the species, and whether additional populations are likely to exist and the basis for this assertion. Provide latitude, longitude, map datum and location name, where available. 22. Is there an ongoing As described in q20, this species is included in the monitoring programme? If so, Christmas Island Island-wide survey program, which please describe the extent and monitors incidence across 900 sites, at two-yearly length of the programme. intervals. However, at the most recent completed monitoring (2009), the blue-tailed skink was not recorded from any sample sites, rendering the IWS an insufficiently powerful design to record ongoing decline (although it may be adequate to monitor increase, should that occur).

Consequently, more intensive regular focused searches of the Boulder Track (until extinction of local population in 2007), North West Point (until extinction of local population in 2009) and the Egeria Point area (to present) have been conducted since 2003.

Life Cycle and Population 23. What is the species’ total The number of individuals in the wild is likely to be fewer population size in terms of number than 200. It is possible that it is zero. of mature individuals? How were population estimates derived and are they reliable? Are there other useful measures of population size and what are they? In the absence of figures, terms such as common, abundant, scarce can be of value.

PART A 24. Does the species occur in a See question 13 above. number of smaller populations? How many? For each population give the locality, numbers and trends in numbers and tenure of land (include extinct populations). Can these be considered to be subpopulations and why? Subpopulations are defined as geographically or otherwise distinct groups in the population between which there is little demographic or genetic exchange. 25. Provide details on ages of the following: a. sexual maturity; Information from captive breeding populations suggests that sexual maturity is likely at age of between 6 and 12 months. b. life expectancy; By analogy with comparable small skink species, longevity is likely to be 3-10 years, probably of the order of 5-7 years. c. natural mortality. There is no information available on natural mortality rates. Of about 100 mature individuals maintained in captivity for at least 12 months, 5-10 have died from suspected natural causes (xxxx unpubl. data). 26. Reproduction For plants: When does the species flower and set fruit? What conditions are needed for this? What is the pollinating mechanism? If the species is capable of vegetative reproduction, a description of how this occurs, the conditions needed and when. Does the species require a disturbance regime (e.g. fire, cleared ground) in order to reproduce? For animals: provide overview of Most information on breeding comes from captive breeding breeding system and of breeding populations, and assessment of breeding status of wild- success, including: when does it caught animals by xxxx (xxxx). Normally two legs are breed; what conditions are needed laid; breeding probably occurs throughout the year. for breeding; are there any Hatching period is about 75 days (from a sample of 84 breeding behaviours that may make eggs monitored in the captive-held population, albeit with it vulnerable to a threatening process? a possible 7 day leeway due to eggs not necessarily being found as soon as laid: xxxx unpubl. data). Other Cryptoblepharus species are known to nest communally (Greer 1989).

Eggs may be susceptible to attack from a wide range of introduced predator species, potentially including giant centipedes Scolopendra subspinipes, black rats Rattus rattus, and Asian wolf snakes Lycodon (aulicus) capucinus. 27. What is the population trend for the entire species? a. What data are there to indicate There are no specific data on decline in population size, but past decline in size (if it is reasonable to assume that it matches the proportional available, include data on rate of decline over past 10 years or decline in distribution. This species was considered to be 3 generations whichever is common (including in disturbed areas) up to at least the longer)? early 1980s (xxxx xxxx). b. What data are there to indicate Population in the wild may increase in the future if future changes in size (if controlled experimental reintroductions or translocations

PART A available, include data which are successful. will indicate the percentage of decline over 10 years or 3 generations whichever in longer (up to a maximum of 100 years in the future) where the time period is a continuous period that may include a component of the past)? 28. Does the species undergo No natural pattern of extreme fluctuations is known or extreme natural fluctuations in likely. population numbers, extent of occurrence or area of occupancy? To what extent and why? Extreme fluctuations can be said to occur in a number of taxa when population size or distribution area varies widely, rapidly and frequently, typically with a variation greater than one order of magnitude (i.e. a tenfold increase or decrease). 29. What is the generation Age at first breeding is likely to be 1 year, and longevity length and how it is calculated? about 5-7 years, so a reasonable estimate of generation Generation length is the average age of parents of the current cohort (i.e. newborn length is 3-4 years. individuals in the population). Generation length therefore reflects the turnover rate of breeding individuals in a population. Generation length is greater than the age at first breeding and less than the age of the oldest breeding individual, except in taxa that breed only once. Where generation length varies under threat, the more natural, i.e. pre-disturbance, generation length should be used.

30. Identify important See q13 above. populations necessary for the species’ long-term survival and recovery? This may include: key breeding populations, those near the edge of the species’ range or those needed to maintain genetic diversity. 31. Describe any cross-breeding Nil. The blue-tailed skink is the only Cryptoblepharus with other species in the wild, species on Christmas Island. indicating how frequently and where this occurs. 32. Departmental Use only:

Populations In Reserve 33. Which populations are in If it persists, the last population occurs at Egeria Point reserve systems? Which of these within Christmas Island National Park. To some extent, are actively managed for this this area is managed for this species through limitations on species? Give details. access, and periodic control of yellow crazy ants Anoplolepis gracilipes. Plans currently in progress aim to reduce or eradicate feral cats (and possibly black rats) from the Island.

Habitat 34. Describe the species’ habitat The blue-tailed skink formerly occurred widely across all (e.g. aspect, topography, substrate, habitats on Christmas Island, including tall primary climate, forest type, associated rainforest, deciduous thickets, coastal thickets, and species, sympatric species). If the settlement areas, including areas scarred and left un- species uses different habitats for rehabilitated by previous mining. In 1979, it was reported different activities (e.g. breeding, to be abundant in household gardens, brick walls and feeding, roosting, dispersing,

PART A basking), then describe each roadside vegetation (Cogger et al. 1983). It was less habitat. common in tall primary rainforest, being recorded more frequently at their edges and in canopy gaps (xxxx xxxx). It was also found commonly foraging on the bare faces of coastal cliffs, often well within the splash zone, retreating to fringing ground cover when disturbed. 35. Does the species use refuge No particular refuge habitat, but it is possible that some habitat, e.g. in times of fire, sites (e.g. rugged limestone pinnacles) used by this species drought or flood? Describe this may be relatively unsuitable for some of its predators (and habitat. potentially also for yellow crazy ants). If so, it is likely to have better persistence at such sites. 36. Is the extent or quality of the Much of Christmas Island has undergone broad-scale species’ habitat in decline? If the ecological change over the last few decades associated species uses different habitats, with outbreaks of yellow crazy ants. Such changes include specify which of these are in marked reduction in the Island’s endemic red crab decline. population, causing increases in the cover of understorey and ground litter. It is plausible that these habitat changes have led to increases in some introduced species that predate on blue-tailed skinks. 37. Is the species part of, or does The blue-tailed skink is not associated with any currently- it rely on, a listed threatened listed threatened ecological community. It occurs (or ecological community? Is it occurred) with a range of other threatened species associated with any other listed including Christmas Island pipistrelle Pipistrellus murrayi threatened species? (EPBCA-listed as critically endangered), Lister’s gecko Lepidodactylus listeri (EPBCA-listed as vulnerable), Christmas Island blind snake Typhlops exocoeti (EPBCA- listed as vulnerable), Abbott’s booby Papasula abbotti (EPBCA-listed as endangered), Christmas Island frigatebird Fregata andrewsi (EPBCA-listed as vulnerable), Christmas Island emerald dove Chalcophaps indica natalis (EPBCA- listed as endangered), Christmas Island goshawk Accipiter hiogaster natalis (EPBCA-listed as endangered), Christmas Island hawk-owl Ninox natalis (EPBCA-listed as vulnerable), Christmas Island thrush Turdus poliocephalus erythropleurus (EPBCA-listed as endangered), Christmas Island shrew Crocidura trichura (EPBCA-listed as endangered), and the plants Tectaria devexa (EPBCA-listed as endangered) and Carmona retusa (EPBCA-listed as vulnerable).

Feeding 38. Summarize the species’ food The blue-tailed skink is an active predator of small items or sources and invertebrates. The food availability is likely to change timing/seasonality. seasonally, being greatest in the wet season. It is highly likely that the abundance of invertebrates (other than yellow crazy ants) is markedly reduced in areas with yellow crazy ant supercolonies. 39. Briefly describe the species’ The blue-tailed skink is diurnal and forages actively on feeding behaviours, including substrates that may make it exposed to some predation those that may make the species attempts. Foraging occurs on the ground, on exposed vulnerable to a threatening process. rocks, low vegetation and the tree canopy.

Movement Patterns (fauna species only) 40. Describe any relevant daily No pronounced dispersal patterns. This species actively and seasonal pattern of forages and basks between 10am and 2pm, activity is far movement for the species, or reduced outside these times. other irregular patterns of

PART A movement, including relevant arrival/departure dates if migratory. 41. Give details of the species’ Home range size is unknown, but is likely to be home ranges/territories. substantially less than 1 ha – individuals probably move over a planar area of tens of metres only.

Survey Guidelines 42. Give details of the This species is unmistakable, relatively conspicuous and distinctiveness and detectability bold. If present, it is likely to be sighted within five of the species. minutes. 43. Describe methods for The Island-wide survey describes a standard technique for detecting species including when monitoring, involving quiet observation at sample points to conduct surveys (e.g. season, for 10 minutes. Shorter (5 mins) and more active time of day, weather conditions); searches are used to survey for it away from these length, intensity and pattern of established sample points. search effort; and limitations and This, and other, reptile species are also sampled using expert acceptance; recommended passive “ink card” techniques, whereby species-specific methods; survey-effort guide. tracks are imprinted on cards left in situ for fixed periods.

Section 2 - Threats and Threat Abatement

Threats 44. Identify past, current and Of the main threatening processes likely to have future threats, to the species contributed to the recent decline of this species, none has indicating whether they are actual yet been definitively proven. or potential. For each threat, describe: Phosphate mining has caused loss of about 25% of forest cover on Christmas Island incrementally since the 1890s. However xxxx (xxxx) reported that this species “appears to thrive in those old mined areas where re-growth consists largely of grasses and low herbs … Such areas, since the extirpation of this species from the settlement area, contain some of the highest density populations of this species”.

The most likely causal factor is predation by one or more exotic species, most likely the wolf snake, giant centipede or yellow crazy ant. Other potential predators include feral cat, black rat, and nankeen kestrel (self-introduced in the 1950s).

A potential threat is disease associated with the introduction and spread of one or more exotic reptile species (Asian House Gecko Gehyra mutilata, Barking House Gecko Hemidactylus frenatus, Grass Skink Lygosoma bowringii, Flowerpot Blind Snake Ramphotyphlops braminus, wolf snake Lycodon capucinus). Of these, G. mutilata and L. bowringi were first recorded from Christmas Island in 1979 (xxxx, xxxx) and L. capucinus in 1987 (Smith, 1988). Competition with these expanding exotic reptile populations is possible, but is unlikely to have been a primary cause of decline.

The blue-tailed skink may also have suffered a reduction in habitat suitability and/or food availability, due to the broad-scale environmental change associated with the development of super-colonies of yellow crazy ants. It is

PART A possible (but there is no supporting evidence) that control mechanisms for yellow crazy ants may have directly or indirectly (through bio-accumulation) poisoned some blue-tailed skinks.Independent scientific research carried out by CESAR Consultants has confirmed that Fipronil ant bait, which is used to control highly invasive crazy ants on Christmas Island, has not accumulated in the environment (soil, water, or invertebrates) (Weeks and McColl 2011). a. how and where it impacts on Mining – impacts largely restricted to the (cumulatively) this species; 25% of the Island that has been cleared and mined. Currently there is no mining of areas containing original native vegetation (primary rainforest).

Increased levels of predation are likely to occur across the Island, associated with (i) the spread of wolf snakes since its introduction in 1987. Other reptiles (and probably their eggs) are a major dietary item for this species; (ii) increased abundance (presumably due to the ecological consequences of yellow crazy ant outbreaks) of giant centipedes; (iii) direct mortality by crazy ants. In contrast to these factors (which have shown relatively recent increase), predation by feral cats has probably been long- standing and shown no recent increase.

In addition to the spread of the wolf snake, two non-native gecko species and one non-native skink species have spread extensively across the Island over the last few decades, in broad inverse correlation to the spatial and temporal pattern of decline of native reptiles. It may be that there is a causal link in this correlation, most likely through spread of a pathogen novel to the Island’s native reptile fauna. However, some preliminary benchmark assays of disease status of non-native reptiles have not demonstrated any likely disease agent (Hall et al. 2011).

Environmental “meltdown” associated with the formation of super-colonies of yellow crazy ants has occurred extensively but patchily across the Island (peaking in 2002, when about 30% of the native forest area was exposed to crazy ant supercolonies), with some impacts pervading beyond super-colony areas (O’Dowd et al. 2003). Episodes of extensive (in 2002 and 2009) and more localised intensive baiting have led to substantial but impermanent reductions in crazy ant densities. James (2005) reported a strong negative correlation between persistence of this species and occurrence of yellow crazy ant colonies. He also undertook experimental studies that indicated no detrimental impacts upon this species of baiting with fipronil (the chemical widely used to control crazy ants). b. what its effect has been so far At this stage it is impossible to link unequivocally the blue- (indicate whether it is known or tailed skink’s decline with any single factor. The most suspected; present supporting information/research; does it substantial evidence is that dietary studies of centipedes only affect certain populations); and wolf snakes confirm predation on lizards (Rumpff 1992; Donnellan et al. 2011), and that both of these predator species have increased (in distribution and abundance) over the period of the decline of the blue-tailed

PART A skink. c. what is its expected effect in The decline of the blue-tailed skink has continued the future (is there supporting inexorably over the last two decades. If it is still present in research/information; is the threat only suspected; does it the wild, it is highly restricted and represented by very few only affect certain populations); individuals. On current trends, it will become extinct in the wild (if it is not already), within a very short time (less than 5 years). d. what is the relative There is no quantitative evidence apportioning the relative importance or magnitude of impacts to the range of candidate threat factors. An the threat to the species. advisory group comprising relevant experts has been established to oversee the captive breeding program. The consensus view from this group is that the most likely driver of decline is increased predation pressure, most likely from either or both the wolf snake or giant centipede. 45. If not included above, identify Cyclones may change vegetation structure on the island, catastrophic threats, i.e. threats but the blue-tailed skink is (or was) a habitat generalist, with a low predictability that are and would not be severely affected by reduction in forest likely to severely affect the species. cover or structure. Identify the threat, explain its likely impact and indicate the likelihood of it occurring (e.g. a drought/cyclone in the area every 100 years). 46. Identify and explain any As a resident of a relatively small island, the blue-tailed additional biological skink has probably long maintained a relatively limited characteristics particular to the amount of genetic variability. The markedly reduced species that are threatening to its current population would have exacerbated this limited survival (e.g. low genetic diversity)? variability. Captive breeding populations are currently being managed to maintain at least 90% of the genetic variability present in their founder stock. 47. Identify and explain any Nil. quantitative measures or models that address the probability of the species’ extinction in the wild over a particular timeframe. 48. Is there other information With the possible exception of the giant gecko that relates to the survival of this Cyrtodactylus sadleiri, all six native reptile species on species that you would like to Christmas Island have declined, with particularly rapid address? recent decline for this species and Lister’s gecko, coastal skink and forest skink. It is plausible that all are affected predominantly by the same factors.

Threat Abatement and Recovery 49. Give an overview of how 1. The blue-tailed skink is now restricted to Christmas broad-scale threats are being Island National Park. The most recent plan of abated/could be abated and other management for this park was established in 2002. A draft recovery actions underway/ Christmas Island National Park Management Plan is proposed. Identify who is currently being prepared and will be released in 2012. undertaking these activities and [Parks Australia] how successful the activities have been to date. 2. A multi-species regional recovery plan (including this species) is currently being prepared . [Parks Australia] 3. An “expert working group” was established by Minister Garrett in 2009 to recommend on conservation management actions and priorities for Christmas Island, and its final report (Beeton et al. 2010) included recommendations for the conservation of the blue-tailed skink. 4. A captive breeding program for this species was established in 2009 by Parks Australia, as recommended in

PART A 2 and 3 above. To date, this operation is not developed through a specific conservation plan, but it is likely to include some experimental re-location trials designed to evaluate the extent of impacts of alternative causal factors. [Parks Australia, in collaboration with Taronga Zoo] 5. The Australian government has committed long-term funding for the ongoing control of yellow crazy ants, consistent with the Threat Abatement Plan. 6. A plan for the control of cats and rats on Christmas Island (Algar and Johnston 2010) is now being implemented. 7. There is an ongoing island-wide biodiversity monitoring program, including this species. [Parks Australia]. 8. Some actions included in the Recovery Plan for Lister’s gecko and the Christmas Island blind snake (Cogger 2006) are relevant to, and would benefit, the management of this species. 50. For species nominated as Although we do not here nominate this species for the extinct in the wild, provide details category of extinct in the wild, we note here that captive of the locations in which the breeding populations are currently maintained on species occurs in captivity and Christmas Island and on the Australian mainland (at the level of human intervention Taronga Zoo). This program has been designed to operate required to sustain the species. over a period of 10 years.

Mitigation Approach 51. Describe any mitigation There has been considerable investment in the control of measures or approaches that yellow crazy ants over the period since the late 1990s, and have been developed specifically for this program continues. [Parks Australia] the species at identified locations. A program to control (or eradicate) feral cats began in Identify who is undertaking these 2010, and has to date resulted in the de-sexing of all pet activities and how successful the cats, and killing of more than 200 “wild” cats. Control activities have been to date. measures have not yet been implemented intensively at the site of the last known blue-tailed skink population. [Parks Australia, in association with WA Department of Environment and Conservation.]

A series of predator exclosure experiments associated with re-introduction trials is now being planned. [Parks Australia]

52. Departmental use only:

Major Studies 53. Identify major studies on the Significant studies of the species’ ecology and status: species that might relate to its taxonomy or management. Andrews, C.W. (ed.) (1900). A monograph of Christmas Island (Indian Ocean) – physical features and geology, with descriptions of the fauna and flora by numerous contributors. British Museum Trustees, London. pp. 1-337.

Cogger, H., Sadlier, R., and Cameron, E. (1983). The Terrestrial Reptiles of Australia’s Island Territories. Australian National Parks and Wildlife Service Special Publication no. 11.

xxxx (xxxx). The terrestrial reptiles of Christmas Island: a reappraisal of their status. Unpublished report to Parks Australia. (Australian Museum, Sydney.)

PART A Gibson-Hill, C. (1947). The terrestrial reptiles. Bulletin of the Raffles Museum 18, 81-86.

James, D. (2004). Christmas Island Biodiversity Monitoring Programme: third quarterly report for the period April to June 2004. Report to the Department of Finance and Administration. (Parks Australia North, Christmas Island.)

James, D. (2005). Christmas Island Biodiversity Monitoring Programme: quarterly report for the period October to December 2004. Report to the Department of Finance and Administration. (Parks Australia North, Christmas Island.)

Schulz, M., and Barker, C. (2008). A terrestrial reptile survey of Christmas Island, May-June 2008. Consultancy report for Parks Australia North, Christmas Island.

Significant studies of the species’ taxonomy:

Horner, P. (2007). Systematics of the snake-eyed skinks, Cryptoblepharus Wiegmann (Reptilia: Squamata: Scincidae) – an Australian-based review. The Beagle. Supplement 3, 21-198.

Management Documentation 54. Identify key management Christmas Island National Park Plan of Management (2010). documentation available for the species, e.g. recovery plans, “regional recovery plan” (in prep). conservation plans, threat abatement plans. Algar, D., and Johnston, M. (2010). Proposed management plan for cats and black rats on Christmas Island. (Western Australia Department of Environment and Conservation, Perth.)

Cogger, H. (2006). National Recovery Plan for Lister’s Gecko Lepidodactylus listeri and the Christmas Island Blind Snake Typhlops exocoeti. (Department of the Environment and Heritage, Canberra.) 55. Departmental use only:

Section 3 — Indigenous Cultural Significance

56. Is the species known to have No particular Indigenous or cultural significance – Christmas Indigenous cultural significance to Island was uninhabited until 1890s. groups within the Australian jurisdiction and, if so, to which Indigenous groups? Are you able to provide information on the nature of this significance?

Section 4 – References and Reviewers

Notes:  The opinion of appropriate scientific experts may be cited (with their approval) in support of a nomination. If this is done the names of the experts, their qualifications and full contact details must also be provided in the reference list below.  Please provide copies of key documentation/references used in the nomination

PART A 57. Reference list Algar, D., and Johnston, M. (2010). Proposed management plan for cats and black rats on Christmas Island. (Western Australia Department of Environment and Conservation, Perth.)

Andrews, C.W. (ed.) (1900). A monograph of Christmas Island (Indian Ocean) – physical features and geology, with descriptions of the fauna and flora by numerous contributors. British Museum Trustees, London. pp. 1-337.

Beeton, B., Burbidge, A., Grigg, G., Harrison, P., How, R., Humphreys, B., McKenzie, N., and Woinarski, J. (2010). Final report of the Christmas Island Expert Working Group to the Minister for Environment Protection, Heritage and the Arts.

Cogger, H., Sadlier, R., and Cameron, E. (1983). The Terrestrial Reptiles of Australia’s Island Territories. Australian National Parks and Wildlife Service Special Publication no. 11.

Cogger, H. (2005). Background Information on Lister’s Gecko Lepidodactylus listeri and the Christmas Island Blind Snake Typhlops exocoeti. (Department of the Environment and Heritage, Canberra.)

Donnellan, S., Armstrong, K., and Potter, S. (2011). Christmas Island National Park centipede genetics. Report to Parks Australia. (South Australian Museum, Adelaide.)

Gibson-Hill, C. (1947). The terrestrial reptiles. Bulletin of the Raffles Museum 18, 81-86.

Greer, A.E. (1989). The biology and evolution of Australian lizards. (Surrey Beatty and Sons, Chipping Norton.)

Hall, J., Rose, K., Spratt, D., Harlow, P., Donahoe, S., Andrew, P., Field, H., DeJong, C., Smith, C., Hyatt, A., and Watson, J. (2011). Assessment of reptile and mammal disease prevalence on Christmas Island. Report to Parks Australia. (Australian Registry of Wildlife Health, Taronga Conservation Society Australia, Sydney.)

Horner, P. (2007). Systematics of the snake-eyed skinks, Cryptoblepharus Wiegmann (Reptilia: Squamata: Scincidae) – an Australian-based review. The Beagle. Supplement 3, 21-198.

O’Dowd, D.J., Green, P.T., and Lake, P.S. (2003). Invasional ‘meltdown’ on an oceanic island. Ecology Letters 6, 812-817.

Rumpff, H. (1992). Distribution, population structure and ecological behaviour of the introduced South-east Asian Wolf Snake Lycodon aulicus capucinus on Christmas Island, Indian Ocean. Report to Australian National Parks and Wildlife Service, Canberra.

Schulz, M., and Barker, C. (2008). A terrestrial reptile survey of Christmas Island, May-June 2008. Consultancy report for Parks Australia North, Christmas Island.

Smith, L.A. (1988). Lycodon aulicus capucinus a colubrid snake introduced to Christmas Island, Indian Ocean. Records of the Western Australian Museum 14, 251-252.

Weeks, A., and McColl, S. (2011). Monitoring of the 2009 aerial baiting of yellow crazy ants (Anoplolepis gracilipes) on non-target invertebrate fauna on Christmas Island. Report to Parks Australia.

58. Has this document been reviewed and/or have relevant experts been consulted? If so, indicate by whom (including current professional position).

PART A This document was prepared with advice from the Christmas Island Reptile Advisory Panel, (Hal Cogger (former curator of reptiles and amphibians at the Australian Museum), Paul Andrew (curator of Taronga Conservation Society Australia), Dr Judy West (Assistant Secretary, Parks Australia), Mike Misso (Manager Christmas Island NP), Dr Mike Smith (Natural Resource Manager, Christmas Island NP), Peter Harlow (Manager, Herpetofauna Division, Taronga Conservation Society Australia), and Dr John Woinarski (Adjunct Professorial Fellow, Charles Darwin University)).