Species Conservation Plan A Conservation Introduction Plan for the Christmas Island Blue-tailed skink, Cryptoblepharus egeriae - Department of ...
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Species Conservation Plan A Conservation Introduction Plan for the Christmas Island Blue-tailed skink, Cryptoblepharus egeriae From: Christmas Island and Taronga Conservation Society, Sydney To: Pulu Blan and Pulu Kembang, Cocos (Keeling) Islands
1 How to cite this report
Director of National Parks 2018. A Conservation Introduction action plan for the Christmas Island Blue-tailed
skink, Cryptoblepharus egeriae, from Christmas Island and Taronga Zoo to the Cocos (Keeling) Islands. Director
of National Parks, Canberra.
Prepared by and CIRAP
Parks Australia
Department of the Environment
GPO Box 787, Canberra 2601
© Copyright Commonwealth of Australia, 2018
With the exception of logos and cover images or where otherwise noted, this report is
licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit
http://creativecommons.org/licenses/by/4.0/
Cover photograph:
Blue-tailed Skink (Cryptoblepharus egeriae), Parks Australia
2
2 Summary
This document is a comprehensive plan for the introduction of the Christmas Island blue-tailed skink
(Cryptoblepharus egeriae) to two small islands of the Cocos (Keeling) islands group. The purpose of
this reintroduction is to establish a wild population as part of this species recovery and security.
Cryptoblepharus egeriae is listed as Critically Endangered under the Environment Protection and
Biodiversity Conservation Act 1999 and is endemic to Christmas Island. Historically, this species was
very common across the island, however, since the 1990s their population has experienced
significant declines. In 2009, 66 C. egeriae were taken into captivity to secure the species future
through captive breeding. By the end of 2010 C. egeriae was presumed extinct in the wild.
The cause of decline is thought to be due to the predation and competition pressures of introduced
species including yellow crazy ants, cats (Felis catus), black rats (Rattus rattus), centipedes
(Scolependra sp), Asian wolf snake (Lycodon capucinus), weeds, birds and geckos (Hemidactylus
frenatus and Gehyra mutilata). Habitat loss and disease are also potential threatening processes.
Captive breeding has been very successful and currently about 1500 C. egeriae exist in captivity
across two locations (Christmas Island and Taronga Zoo, Sydney). Threat mitigation of yellow crazy
ants, cats and rats is underway and will go a long way to reducing the pressure on the reptiles if they
are reintroduced back to Christmas Island. The continued presence of wolf snakes and centipedes
and the inability to control or eradicate these species easily is of high concern and poses a great risk
of never being able to successfully reintroduce this species back to their native habitat. Finding
solutions for reintroduction beyond captive breeding is critical for avoiding extinction of both
species.
This document addresses the legal, ethical, ecological and logistical issues associated with moving
and introducing C. egeriae to the Cocos (Keeling) Islands in 2019 as an alternative to wild release on
Christmas Island.
3
3 Contents
1 How to cite this report ....................................................................................................................... 2
2 Summary ............................................................................................................................................ 3
1 Project management .......................................................................................................................... 4
1.1 Proponent................................................................................................................................... 4
1.2 Project Sponsor: ......................................................................................................................... 4
1.3 Project co-ordinator: .................................................................................................................. 4
1.4 Project oversight ........................................................................................................................ 4
1.5 Resourcing .................................................................................................................................. 6
2 Project rationale ................................................................................................................................. 7
2.1 Goal ............................................................................................................................................ 7
2.2 Objectives ................................................................................................................................... 7
2.3 Type of conservation action ....................................................................................................... 7
2.4 Taxonomy of the species ............................................................................................................ 7
2.5 Legal Status of the species ......................................................................................................... 7
2.6 Documented recovery actions ................................................................................................... 8
2.7 Justification for conservation action .......................................................................................... 8
2.8 Consequences of not proceeding with the proposed action ..................................................... 9
2.9 Criteria for Success ..................................................................................................................... 9
2.10 Previous work ............................................................................................................................. 9
2.11 Number of individuals of the species being conserved and proposed project timing ............ 11
3 Biology and ecology.......................................................................................................................... 14
3.1 Morphology .............................................................................................................................. 14
3.2 Reproductive cycle and timing ................................................................................................. 14
3.3 Distribution and abundance ..................................................................................................... 14
3.4 Habitat requirements ............................................................................................................... 14
3.5 Nutritional requirements ......................................................................................................... 14
3.6 Reasons for decline and current threats .................................................................................. 14
4 Source environment, population and distribution........................................................................... 20
4.1 Site tenure ................................................................................................................................ 20
4.2 Source environment ................................................................................................................. 20
4.3 Demographics of source population ........................................................................................ 20
4.4 Impact of the removal of individuals from the source population .......................................... 20
4.5 Methods of collection and transfer.......................................................................................... 20
5 Holding site conditions ..................................................................................................................... 22
5.1 Site tenure ................................................................................................................................ 22
5.2 Holding site environment ......................................................................................................... 22
5.3 Species reproduction in captivity ............................................................................................. 22
5.4 Managing known and potential threats ................................................................................... 22
6 Host environment............................................................................................................................. 23
6.1 Site tenure and level of conservation protection .................................................................... 23
6.2 Host environment..................................................................................................................... 23
6.3 Is the site part of the historically known range for the species? ............................................. 26
6.4 Why the species cannot be conserved within its known range ............................................... 26
6.5 How the habitat requirements of the species will be met ....................................................... 26
6.6 Managing known and potential threats ................................................................................... 26
6.7 Release and facilities to be used .............................................................................................. 27
6.8 Consequences of the translocation on the viability of the host population ............................ 27
6.9 Dispersal of individuals and the carrying capacity of the habitat ............................................ 27
6.10 Potential environmental impacts ............................................................................................. 27
7 Monitoring and research .................................................................................................................. 28
7.1 Monitoring in the first three months post-release .................................................................. 28
7.2 Medium to long term monitoring ............................................................................................ 28
7.3 How monitoring will inform management ............................................................................... 30
8 Risks .................................................................................................................................................. 31
8.1 Risk assessment and handling strategies ................................................................................. 31
8.2 Thresholds that determine requirement for withdrawal from the project, and exit strategy.31
9 Communications plan....................................................................................................................... 32
2
9.1 Stakeholders and public communication plan ......................................................................... 32
10 List of Appendices ........................................................................................................................ 32
11 References .................................................................................................................................... 33
31 Project management
1.1 Proponent
A/g Director of National Parks
1.2 Project Sponsor:
Sebastian Lang
A/g Assistant Secretary
Parks Island and Biodiversity Science Branch
1.3 Project co-ordinator:
Natural Resource Manager (Threatened Species)
Christmas Island National Park
1.4 Project oversight
Due to the significant decline of Christmas Island’s native reptiles and the need to access specialist
advice and expertise for their conservation, in 2011 the Christmas Island Reptile Advisory Panel
(CIRAP) was formed to:
1. Provide advice and direction to the Director of National Parks (DNP) and Taronga Zoo on the
Christmas Island Reptile Conservation Program, in particular the captive breeding and
reintroduction program.
2. Assist in the development of appropriate collaborations with other research and environmental
management organisations.
Membership comprises people from various backgrounds including conservation managers,
reptile/monitoring experts and a geneticist (see Table 1). Meetings are held at-least twice per year via
teleconference.
While this plan prescribes envisaged actions for a 10 year period, it is recognised that there will be a
need to respond to uncertainty or changing circumstances over the plan’s life. Consequently, continuing
to access advice from CIRAP (and as needed other relevant experts) is considered an essential
underpinning action, in order to enable an adaptive evidence based approach to the implementation of
this plan. Therefore, this plan is considered a working document that may be changed over time based
on new evidence and advice.
Table 2 outlines other organisations and stakeholders involved in this project.
4Table 1: CIRAP membership
Name Organisation Role
Sebastian Lang Parks Australia Assistant Secretary, Parks and Biodiversity Science
Branch
Parks Australia Manager, Christmas Island and Pulu Keeling National
Parks
Parks Australia Natural Resource Manager (Threatened Species)
Christmas Island National Park
Taronga Conservation Manager
Society Australia Herpetofauna Division
Taronga Conservation Curator (former)
Society Australia
Dr Hal Cogger Independent expert Former curator of reptiles and amphibians at the
Australian Museum (1960-1975) and Deputy Director
(1976-1995). Author of the National Recovery Plan for
Lister’s Gecko and the Christmas Island Blind Snake
Charles Darwin Professorial Research Fellow
University
Deakin University Director, Centre for Integrative Ecology
Director, TechnEcology Research Network
President, Ecological Society of Australia
School of Life and Environmental Sciences
Taronga Conservation DVM, DVSc
Society Australia Australian Registry of Wildlife Health
Table 2: Internal and external stakeholders
Name Organisation Role
Christmas Island Independent advisory Provides advice on the captive breeding
Reptile Advisory Panel panel and reintroduction of Christmas Island
(CIRAP) reptiles
Christmas Island Parks Australia Is responsible for the reptile captive
National Park breeding program on Christmas Island,
development of this plan, translocation of
C. egeriae to Cocos, training of PKNP staff
and initial monitoring
and Taronga Conservation Is responsible for the reptile captive
Taronga Zoo Society breeding program at Taronga Zoo, provides
advice on genetic and husbandry
management of the species and
contributor to this plan
Pulu Keeling National Parks Australia PKNP will assist in the pre-release
Park (PKNP) assessments of the destination islands,
assist with community consultations and
have responsibility for long-term
monitoring of the introduced population
Animal Ethics Taronga Conservation Ethics approval for the project
Committee Society
EPBC Permits Department of the Responsible for the assessment and
Environment and Energy approval of threatened species permits
Department of Agriculture Responsible for the assessment and
and Water Resources approval of live animals imports from
Christmas Island and Sydney to the Cocos
(Keeling) Islands
CEO and Councillors Cocos (Keeling) Shire Responsible for the management of Pulu
Council Blan and Pulu Kembang
Cocos community
51.5 Resourcing
The overarching reptile conservation program is funded through the CINP operational budget. This
funds one full-time reptile keeper and provides a small budget to cover operational expenses.
Additional funds are received for a Memorandum of Understanding (MoU) with Taronga Conservation
Society for the captive management and advice on genetic management of Christmas Island reptiles.
The proposed conservation introduction predominantly relies on staff time for maintenance of the
captive colony, on-going monitoring and threat mitigation. An additional budget is required to cover
short-term casual staff, operational expenses and travel. A breakdown of these costs are outlined in
Table 3. Note that the bulk of staffing and fixed costs is covered by existing operational funding and
has not been included here. Staffing costs included are for additional temporary staff to undertake rat
eradication on the destination islands and to assist with maintaining the captive colony at the level
required to support reintroduction activities (i.e. approximately 1,000 individuals per species). All costs
included here are not currently budgeted for.
Table 3: Estimated costs of implementing this plan
Item Financial year
2018-19 2019-20 2020-21 2021-22 2022-23 2023-24 2024-25 2025-26 2026-27
Rat eradication
Staffing $8,430 $8,430
(APS3 – 5 week period)
Flights $570 $570
Accommodation $8,250 $8,250
Travel allowance $3,225 $3,225
Bait & equipment $3,120 $2,550
Movement of animals
Flights CI to Cocos $5001 $500 $500 $500 $500 $500
Flights Sydney to $2,0002 $2,0002 $2,0002 $2,0002 $2,0002 $2,0002
Cocos
Accommodation
2 x Overnight Perth $4002 $4002 $4002 $4002 $4002 $4002
Cocos (1 x Taronga) $1,0002 $1,0002 $1,0002 $1,0002 $1,0002 $1,0002
Cocos (1 x CINP) $2,5003 $2,5003 $2,5003 $2,5003 $2,5003 $2,5003
Travel allowance $1,2903 $1,2903 $1,2903 $1,2903 $1,2903 $1,2903
Monitoring $5,0004 $5,0004 $5,0004 $5,0004 $5,0004 $5,0004 $5,0004 $5,0004
Captive breeding
Staffing (0.8 x APS2) $32,8075 $65,6135
TOTAL UNFUNDED $64,092 $101,898 $12,690 $5,000 $12,690 $5,000 $12,690 $5,000 $12,690
1 Release of animals to Pulu Kembang will be in 2018-19 and Pulu Blan in 2019-20. Subsequent releases to both islands will be
concurrent and only require 1 trip.
2 Possibly covered by Taronga MoU payment but have been included here to reflect total cost. Accommodation budget is for
1 person for 4 nights.
3 Accommodation for CINP staff is for 10 nights and may not be required if shared staff accommodation is available at no cost.
Travel allowance is based on $129/day.
4 Monitoring costs include additional boating costs that will be incurred by PKNP to monitor introduced populations.
5 Staffing costs for 2018-19 is for 0.8 APS2 for 6 months including on-costs. 2019-20 budget is for 0.8 APS2 for 12 months
including on-costs.
62 Project rationale
2.1 Goal
• Introduce two self-sustaining wild populations of C. egeriae to two separate islands
on the Cocos (Keeling) Island group by 2020 to secure the future of the species
outside of captivity. This will include an initial release of up to 300 individuals on
each destination island in 2019 and subsequent releases every two years until 2027.
2.2 Objectives
• Continue captive breeding programs on Christmas Island and at Taronga Zoo to
secure a source population for introduction and subsequent releases until 2027.
• Gain necessary approvals, permits and community support for the project by
December 2018.
• Achieve chicken removal and rat eradication on Pulu Kembang by June 2019 and
Pulu Blan by December 2019, see Appendix D for details on the planned rat
eradication.
• Select a genetically diverse founder population from the Christmas Island and
Taronga Zoo captive populations for release by February 2019.
• Transport and release up to 300 animals to Pulu Kembang by June 2019 and Pulu
Blan by December 2019 pending chicken and rat removal.
• Monitor the introduced population post-release to record successful establishment.
2.3 Type of conservation action
Under the revised IUCN reintroduction guidelines a conservation introduction is defined as the
intentional movement and release of an organism outside its indigenous range. Two types of
conservation introductions are recognised:
a. Assisted colonisation is the intentional movement and release of an organism outside its
indigenous range to avoid extinction of populations of the focal species.
This is carried out primarily where protection from current or likely future threats in current range is
deemed less feasible than at alternative sites.
b. Ecological replacement is the intentional movement and release of an organism outside its
indigenous range to perform a specific ecological function.
This is used to re-establish an ecological function lost through extinction, and will often involve the
most suitable existing sub-species, or a close relative of the extinct species within the same genus.
The proposed action is classed as an assisted colonisation as C. egeriae will be moved to an area
outside of its indigenous range to help avoid potential extinction.
2.4 Taxonomy of the species
The species is conventionally accepted as Cryptoblepharus egeriae (Boulenger, 1889). Cryptoblepharus
egeriae is in the Family Scincidae. This species is endemic to Christmas Island.
2.5 Legal Status of the species
Cryptoblepharus egeriae is listed as Critically Endangered under the Environment Protection and
Biodiversity Conservation Act 1999. A Conservation Advice exists for this species effective from
3/1/2014. Priority research actions include:
7 Investigate options for establishing additional populations from captive-bred stock;
Undertake adaptive release trials, such as through the use of enclosures, to trial the reintroduction
of captive-bred individuals into the wild; and
Monitor the status of introduced individuals.
Internationally C. egeriae is listed on the IUCN Red List of Threatened Species as Extinct in the Wild
(IUCN, 2018). Conservation actions for C. egeriae include:
The release of captive animals into outdoor enclosures protected from predators; and
Release to the Cocos (Keeling) Islands.
2.6 Documented recovery actions
Table 4: Summary of recovery actions and their status as per the Conservation Advices
Blue-tailed skink (BTS), Cryptoblepharus egeriae
Recovery actions Source Status
Monitor areas where the BTS was last known to occur to Monitoring undertaken until
help identify key threats and determine the relative 2012
impacts of potential threats.
Ensure there is no disturbance in areas where the BTS was Achieved
last known to occur, excluding necessary actions to
manage the conservation of the species.
Effectively manage any known, potential or emerging YCA biological control
threats to the BTS, such as introduced predators and implemented, cat eradication
diseases, particularly in areas where the species was last occurring, targeted centipede
known to occur/potential habitat. and wolf snake control occurring
at soft-release site (but
Conservation impossible island-wide), disease
Advice
being investigated
Control and reduce the impacts of introduced pests As above
including the feral cat, rat, yellow crazy ant, Asian wolf
snake and giant centipede on Christmas Island,
particularly at sites where BTS is known to have
previously occurred, by developing or implementing
existing management plans to control these species.
Monitor the effectiveness of management programs to Control programs independently
control population numbers of feral animals. reviewed periodically
Improve biosecurity on Christmas Island to maintain Biosecurity alerts distributed for
effective quarantine against the introduction of diseases, potential new introductions
parasites, pathogens and invasive species.
If a disease, fungi and/or parasite is found to be impacting Disease currently being
upon, or may potentially impact upon BTS, implement investigated
appropriate management actions to minimise the adverse
impacts of such threats.
Continue to support and enhance the captive breeding Ongoing
program for the species with the aim of breeding enough
genetically diverse individuals to enable future re-
establishment of wild populations.
Develop educational and awareness raising programs Ongoing
regarding the blue-tailed skinks’ status, threats and
recovery activities.
2.7 Justification for conservation action
The Director of National Parks Corporate Plan 2018-2022 supports the finalisation of the feasibility study
(Appendix E) for the introduction of C. egeriae to the Cocos (Keeling) Islands which in broad terms
includes a trial release.
8The Christmas Island National Park Management Plan 2014-2024 also seeks to maintain and adaptively
develop conservation programs for terrestrial reptiles under threat from extinction in the wild (Action
4.3.12).
The objective of the CINP Reptile Conservation Program is to conserve and restore populations of
native reptile species on Christmas Island, with all extant species persisting in the wild. This includes a
subsidiary objective to successfully reintroduce C. egeriae back into the wild.
There is a high chance that successful reintroduction of the blue-tailed skink is not possible on
Christmas Island due to the ongoing pressures of the Asian wolf snake and giant centipede. Looking at
alternative options for reintroduction is crucial for managing this species into the future.
The reptile conservation work associated with this Plan will help enhance the recovery of C. egeriae by
establishing a wild population in a location where its main threats are absent. The action is not likely to
have any negative impacts to the native flora and fauna at the release location and the pre-release
works of rat eradication and chicken removal will only seek to enhance the local environment.
The destination islands, Pulu Blan and Pulu Kembang, were ranked as the top two most suitable islands
for the conservation introduction because of their accessibility, abundant invertebrate population and
suitable habitat. They are also relatively isolated and will not connect via land bridge to other islands at
low tide and will provide the best chance of survivorship for C. egeriae.
2.8 Consequences of not proceeding with the proposed action
If suitable options for reintroduction are not found on Christmas Island and the proposed conservation
introduction is not trialled, then there is a real chance that C. egeriae will remain in captivity
indefinitely.
2.9 Criteria for Success
To provide standards for the evaluation of the project’s success, the following criteria will be used:
Short-term (six months): Eradication of rats from the destination islands
Removal of chickens
Successful transfer of up to 300 animals from captivity to the release site
Signs of mating and reproduction (e.g. bite marks or gravid females)
>60% survivorship of animals six months post-release on one or two of the
release islands (to be informed by soft-release on Christmas Island)
Medium-term (one year): Absence of introduced predators
Stable population of at least 60% of the release population on at least one
of the two release islands (prior to second release)
Successful transfer of additional animals from captivity to the release site
Successful recruitment (persistence of newly recruited animals to at least
6 months of age) on at least one of the two release islands
Long-term (> two years): Absence of introduced predators
Stable/organically growing population* on at least one of the two release
islands
Successful recruitment (persistence of recruited animals to adult age) on
at least one of the two release islands
Successful transfer of additional animals from captivity to the release site
(dependent on success achieved in criteria above)
* Actual target population size is highly speculative and dependent on a number of variables including habitat preference, food availability,
carrying capacity and complete transfer numbers. Through monitoring, carrying capacity of the island(s) may be identified.
2.10 Previous work
By 2009 it was recognised that the wild population of C. egeriae was rapidly declining and, over the
course of 2009 and early 2010, a total of 66 individuals were collected from the wild to establish a
captive colony on Christmas Island.
9Prior to genetic management advice, captured animals were intermittently moved between enclosures
(approximately every 6 months), whilst avoiding the possibility that mature offspring would be housed
with either their siblings or parents. All captured animals and their offspring were given an identifying
toe-clip at this time. In May 2011, eight C. egeriae captive populations were established. Animals were
grouped according to their capture location and genetic heritage following genetic management
advice from Taronga Zoo Threat mitigation.
By the end of 2011, the captive population size of C. egeriae had almost doubled. These populations
were split into two colonies with one colony remaining on Christmas Island and the other transported
to Taronga Zoo, Sydney. In three shipments, a total of 83 C. egeriae were transferred to Taronga Zoo
to establish a second insurance population.
Since the establishment of a captive colony, the population has significantly increased and as of June
2018, 1629 individuals exist in captivity.
In 2017, an attempt was made to reintroduce 139 C. egeriae into a soft-release site on Christmas
Island. The attempt was unsuccessful and the site was reconstructed in 2018 following significant
improvement works and predator removal. In August 2018, 170 C. egeriae were released and news of
successful establishment is still pending.
NESP PhD research
Whilst the first reintroduction attempt was unsuccessful in 2017, we learnt a number of valuable things
including; (1) food availability appeared sufficient as all animals recaptured during mark-recapture
sessions had maintained or put on weight since release, and (2) lizards were observed still maintaining
antipredator behaviour towards avian predators. Unfortunately, the primary reason was not identified,
however a few hypotheses were developed which include (1) did introduced giant centipedes play a
significant role in the demise of this population, (2) was the habitat suitable to maintain a population of
blue-tailed skinks and (3) did natural avian predators predate heavily on blue-tailed skinks. Points two
and three are being investigated in much more detail currently in the second release that occurred in
August 2018. Before this release, CINP staff significantly increased the complexity, connectivity and
amount of habitat available, and we are stringently monitoring what habitat they favour and to assess
whether there is enough. To do this we will use selectivity indices. This is a method to see whether a
species are disproportionately favouring a specific habitat type, and if they are, is there a sufficient
amount of it and if there isn’t, can we increase this habitat to make the site more suitable for them.
Furthermore, we are currently undertaking an experiment to elucidate relationships between blue-
tailed skinks and giant centipedes (Scolependra sp.) to investigate whether they may have played a
significant role in the decline of the reintroduced population of blue-tailed skinks. Whilst we undertook
removal of centipedes from the soft release site, we did not realise the sheer densities of centipedes in
the site, and we therefore want to know whether they can and do predate skinks in large numbers. To
do this, we have set up six 25m2 exclosures with two different centipede densities to assess survival over
time, but also tease out whether the skinks choose/share retreat sites that contain centipedes.
Preliminary analysis is starting to indicate an effect after 7 weeks at high (6 centipedes over 10cm)
centipede densities, however there is no such effect yet at small centipede densities (2 centipedes over
10cm). Irrespective of the result, centipedes have been eradicated from the soft release site before blue-
tailed skinks were re-released in August 2018, however this experiment will be incredibly important for
two reasons; (1) were they responsible for the decline of that population and (2) if they were, does
density play a role and how much management needs to be done to keep the site centipede free?
10Finally, the only predators believed to be able to access the site are avian threats, primarily the Christmas
Island thrush and Christmas Island Goshawk. We will spend time monitoring interactions between these
birds and blue-tailed skinks. Once the blue-tailed skinks has become established in area, we will set up
a number of remote triggered motion cameras to see whether and how often these possible predators
are spending trying to consume skinks.
2.11 Number of individuals of the species being conserved and proposed
project timing
This project proposes to harvest up to 150 individual C. egeriae from each of the two captive
populations (i.e. Christmas Island and Taronga Zoo) on eight to ten separate occasions from 2019 to
2027 (i.e. 150 x 2 x 10 = a total of 3,000 C. egeriae over 8 years). The number of animals harvested on
each occasion will depend on how many excess animals are available from the captive colonies. The
number of animals harvested from both colonies will always be equal to support genetic management
goals. On the final year, up to 500 C. egeriae will be swapped between the two destination islands to
enhance genetic diversity. The harvested BTS will comprise a mixed cohort (including juveniles, sub
adults and adults) containing both sexes, harvested equally from both remaining captive populations.
The number and age class of animals to be used in this project was determined in consultation with
Taronga Zoo to ensure that genetic diversity is maintain and that the introduced population has the
best chance of successful establishment. Whilst tables 5 to 9 outline the steps for the initial release in
2019, the tasks in tables 7-9 are still applicable for all subsequent releases and monitoring. Due dates
for activities 2020 onwards will be planned annually.
Table 5: Planning phase
Item Description of Major Tasks Due Date
1 Seek Executive Board approval November 2018
2 Seek approval from the Shire of Cocos (Keeling) Islands September 2018
Apply for import approval through the Department of Agriculture and Water Before June
3
Resources 2019
4 Apply for animal ethics approval through Taronga Conservation Society September 2018
5 Apply for EPBC Part 13 permit November 2018
6 Undertake an environmental referral self-assessment July 2018
7 Circulate all documents through CIRAP November 2018
8 CIRAP meeting #14 February 2019
11Table 6: Preparation and extraction
Due Date
Item Description of Major Tasks Pulu
Pulu Blan
Kembang
Habitat improvement; Provide canopy openings (fell coconut), November November
1
weeding, tree planting if necessary 2018 2018
November
2 Removal of introduced geckos pre-release if necessary May 2019
2019
3 Rat eradication from destination islands January 2019 August 2019
December
4 Chicken relocation June 2019
2019
December
5 Preparation of animal transport containers as per ethics approval June 2019
2019
Capture and health assessment of captive animals for release December
6 June 2019
including weight, morphometric measurements and toe-clips 2019
Table 7: Treatment while in captivity
Item Description of Major Tasks Due Date
Standard Christmas Island Reptile Captive Breeding program animal
management as per the ‘Christmas Island National Park Reptile Conservation
1 Ongoing
Plan 2014-2024’ and ‘Christmas Island Terrestrial Reptile Captive Breeding
Program Manual’
Completion of Reptile census, exclosures cleaned, animal health checks,
2 February 2019
identification of release numbers and age cohort
Table 8: Species first release (subsequent release due dates will occur in 2021, 2023, 2025 and 2027)
Due Date
Item Description of Major Tasks Pulu
Pulu Blan
Kembang
Package animals for transport from Sydney to Cocos and December
1 June 2019
Christmas Island to Cocos 2019
Quick health assessments on arrival to Cocos as per guidelines December
2 June 2019
outlined in the animal ethics application 2019
Depending on flight times/delays and weather conditions, December
3 animals may be immediately released or held for 1-3 nights June 2019 2019
before release to destination island
Animals will be released late afternoon to strategic areas within December
4 June 2019
the site that contain a significant amount of refugia 2019
12Table 9: Post-release monitoring and reporting following first release (subsequent post-release monitoring and reporting will
occur in 2021, 2023, 2025 and 2027)
Due Date
Item Description of Major Tasks Pulu
Pulu Blan
Kembang
1 Weekly monitoring for one month July 2019 January 2020
December June 2020
2 Monthly monitoring from 2-6 months
2019
3 CIRAP #16 (report on C. egeriae release on Pulu Kembang) November 2019
CIRAP #17 (report on C. egeriae survivorship, monitoring and C.
4 June 2020
egeriae release on Pulu Blan)
5 Monthly Project Status Report monitoring Ongoing
133 Biology and ecology
3.1 Morphology
3.2 Reproductive cycle and timing
Cryptoblepharus egeriae is oviparous and can lay multiple clutches of one-two eggs per breeding
season. In captivity, the breeding season is from October to April. Eggs are generally laid in moist areas
under leaf litter or bark and take approximately two months to incubate.
3.3 Distribution and abundance
Formally, C. egeriae was widely distributed across Christmas Island. However they are no longer found
in the wild and exist only in captivity at two locations, Christmas Island and Taronga Zoo, Sydney.
3.4 Habitat requirements
Cryptoblepharus egeriae favoured a wide variety of habitats on Christmas Island including; primary
rainforest, thickets, coastal areas and disturbed/modified habitat. In 1979, it was reported as
abundant in household gardens, brick walls and roadside vegetation but less common in primary
rainforest where it was found in clearings (Cogger, Sadlier et al. 1983).
3.5 Nutritional requirements
Cryptoblepharus egeriae feeds on a variety of small invertebrates including crickets, grasshoppers,
termites, spiders and moths. These invertebrates naturally occur within the host environment.
3.6 Reasons for decline and current threats
No single known causal factor has been identified as being responsible for the decline of the CI native
reptile fauna. It is likely a combination of factors has contributed to their decline. Table 10 identifies a
number of possible threats that have been implicated in the decline of the CI reptile fauna, the history
of their introduction, an overview on their likely impact (Smith et al., 2012) and how they are currently
being managed.
A number of these threats were considered by the Christmas Island Reptile Advisory Panel (CIRAP),
which was established by the DNP in 2011 to inform the conservation of Christmas Island’s reptiles. At
the first CIRAP meeting on 5 August 2011 (and based on expert opinion), threats were prioritised on
the extent of their likely detrimental impact, the level of current management response as well as the
likelihood of reptiles persisting with or without the presence of these pressures. The presumed threats
that remain uncontrolled and/or do not have resources currently allocated for investigating techniques
for their control were prioritised. This information is also included in Table 10.
It was however recognised that there is little, and insufficient, empirical basis for evaluating the
relative impacts of these factors, and a key priority is to undertake research that can better resolve the
threat context. Current PhD research by will help to address this issue.
14Table 10: Possible threats to Christmas Island native reptiles
Threat History Role in reptile declines Management
Yellow Crazy Ants Early 1900s – introduced Unknown but has most 1999 – Crazy Ant Steering Committee established (now CASAP)
accidentally via shipping likely significantly impacted
2000 – hand and aerial baiting program commenced. Hand baiting has been
on food resources by
1990s – discovery of undertaken when needed
reducing invertebrate
destructive supercolonies
diversity and abundance 2001 – the first biennial island-wide survey was conducted and has been
Distribution of supercolonies and habitat quality undertaken every two years since
has changed overtime with
2002 – first aerial baiting campaign. Over 2500ha baited
control efforts
Impact on reptiles 2005 – YCAs listed as Key Threatening Process to the Biodiversity on CI
YCAs have affected about
under the EPBC Act
39% of the island in total MODERATE
2006 – YCA identified as a priority species in the Threat Abatement Plan to
In 2012, supercolonies
Reduce the Impacts of Tramps Ants on Biodiversity in Australia and its
spread across about 8% of
Territories
the island
2009 – second aerial baiting campaign. Approximately 500ha baited.
Commencement of three year research into YCA biological control
2012 – third aerial baiting campaign. Approximately 1067ha baited
2013 to 2015 – hand baiting and implementation of YCA biological control
2016 to 2018 – rearing and island-wide release
CIRAP acknowledged that the control of Yellow Crazy Ants is a priority for
broader biodiversity conservation on the island and a management plan
exists which guides a well-established control program. Although an
important issue, CIRAP considered that it did not need to be addressed
separately for the purposes of reptile conservation as it was already being
addressed and advised by the Crazy Ant Scientific Advisory Panel (CASAP).(Table 10 continued)
Threat History Role in reptile declines Management
Competition with Introduced accidentally Unknown but has most No current management in place
non-native reptiles probably via shipping. Initially likely competition for
CIRAP considered this threat as a lower priority at the time with respect to
restricted to disturbed areas resources and habitat as
other pressures highlighted, however, introduced geckos have been
well as the spread of
1947 – H. frenatus (Gibson- implicated in native gecko declines in the Pacific Islands and warrants further
disease/parasites (see
Hill, 1947) investigation on Christmas Island.
disease/parasites)
1979 – G. mutilata (Cogger
et al., 1983)
Impact on reptiles
1979 – L. bowringii (Cogger
et al., 1983) MODERATE
1987 – L. capucinus (Smith
1988)
1980s – observations of
introduced reptiles beginning
to spread into undisturbed
areas (Cogger et al., 1983)
Habitat disturbance 1898 – phosphate mining Generally loss of habitat 1980 – the south western corner of the island is protected under the National
and fragmentation commenced and has been although some species Parks and Wildlife Conservation Act 1975 and Christmas Island National Park
almost continuous since were common in settled is declared
areas and old mine sites
1989 – no further clearing of 1986 – Christmas Island National Park was extended in two stages
primary rainforest allowed
1989 – A further addition to Christmas Island National Park including wetland
Impact on reptiles and marine areas and much of the island’s remaining undisturbed rainforest
LOW Future clearing is subject to assessments under the Environmental Protection
Act 1986 (WA)(CI).
Climate Change Unknown Unknown but changing No current management in place
temperatures and periods
CIRAP considered this as a lower priority at the time with respect to other
of wet and dry may impact
pressures highlighted.
on reproductive success
16(Table 10 continued)
Threat History Role in reptile declines Management
Cats 1888 - introduced by early Predation of native reptiles 1981 – survey of feral cat distribution (Yorkston, 1981)
settlers
1989 – Survey of terrestrial mammals (Tidemann, 1989)
Initially cats were
Impact on reptiles 1994 – Cat dietary studies confirming native reptile predation (Tidemann et
concentrated around
al., 1994)
settlement and mining areas LOW to MODERATE
but with the movement of 1997 – Cat dietary studies confirming continued predation on native reptiles
black rats across the island, (van der Lee, 1997)
feral cats become more
widespread and are now 2002 – Cat dietary studies inferred by scats showed a shift in diet to
predominantly birds and insects (Corbett et al., 2003)
found island-wide
2005, 2008 – survey of feral cat distribution and abundance and diet in 2005
(Algar and Brazell, 2005, 2008)
2010 – a threat abatement plan implemented for cats and black rats.
Introduction of council cat by-laws. Domestic cat registration and de-sexing.
2011-2012 – annual domestic cat survey and de-sexing. Control of stray and
feral cats in residential and industrial areas and along major road ways (2012
only)
2013 - annual domestic cat survey. Control of stray and feral cats in
residential and industrial areas and along major road ways. Approximately
502-595 feral cats removed to date
2014 – maintain current control efforts until further funding is secured for
island-wide eradication
2015 – commence island-wide eradication
CIRAP considered the control/eradication of cats a priority for broader
biodiversity conservation on the island and noted that a threat abatement
plan exists. There was agreement that cat control did not need to be
addressed separately for the purposes of reptile conservation.
17(Table 10 continued)
Threat History Role in reptile declines Management
Centipedes Introduced accidentally via Unknown but predation No current broad-scale management in place
shipping in the early 1900’s and/or competition for
Targeted control at a soft-release site
and thought to have habitat or food may have
significantly increased in been a contributing factor CIRAP noted that little is known about the effects of centipedes on reptile
abundance by the 1990’s survivorship, therefore investigating the impacts of centipedes was
considered one of the most immediate issues for successful reintroduction of
Impact on reptiles reptiles back into the wild.
MODERATE-HIGH
Wolf snakes Thought to have been Likely to play a significant 1992 – survey into the distribution, population, structure and ecological
introduced accidentally via role in the disappearance of behaviour of the wolf snake including diet analysis (Rumpff 1992)
shipping around 1987 native reptile species
1999 – wolf snakes included in a terrestrial reptile survey (Cogger and Sadlier
through predation.
1999)
Impact on reptiles
2004-2006 – wolf snake study included in the Christmas Island Biodiversity
HIGH Monitoring Program including 200 dissections and nocturnal surveys (James
2007)
2008 - wolf snakes included in a terrestrial reptile survey (Schulz and
Heywood Barker 2008)
2008-present – Opportunistic and targeted wolf snake monitoring/gut
contents analysis conducted by DNP
2016 – wolf snake Master’s research undertaken
2018 – Targeted control at a soft-release site
CIRAP noted that wolf snakes have been implicated in the decline of native
reptiles through their dietary preferences. The pattern of decline or the native
reptile species has closely matched the spread of the wolf snake from East to
West across the island. Furthermore, native reptiles were frequently detected
in the stomach contents of dissected wolf snakes. Investigating techniques
for wolf snake control was considered one of the most immediate issues for
successful reintroduction of reptiles back into the wild.
18(Table 10 continued)
Threat History Role in reptile declines Management
Rats 1899 – introduced Unknown but predation on 2010 – a threat abatement plan implemented for cats and black rats
accidentally via shipping reptiles and/or eggs may be
2012 to 2014 – settlement foreshore baiting
a likely contributing factor
Rats brought a disease
2014 onwards – community rat baiting
parasite, murid trypanosome,
which was transmitted by 2016 – PhD project focusing on meso-predator relationships and impact of
Impact on reptiles
fleas to native rats rats post cat removal
LOW
Within less than 10 years
from the time of introduction
native rats became extinct
Red Jungle Fowl Introduced during settlement Unknown but predation on No current management in place
reptiles may have been a
Abundant in settled and
contributing factor
disturbed areas
Impact on reptiles
LOW
Disease/parasites Unknown Unlikely to have played a 2010 – The Director of National Parks commissioned a study to assess
role in decline however the whether parasites, disease and/or heavy metals were key contributing factors
discovery of enterococcus in the reptile declines. This study was undertaken by the Australian Registry
in 2014 may impact on of Wildlife Health (Taronga Conservation Society Australia)
reintroduction
2011 – Hall et al. (2011) reported on this study. They found no evidence that
disease, pathogens or heavy metals were contributing factor to the declines
Impact on reptiles 2014 – Discovery of a new disease in geckos which was later confirmed as a
new enterococcus bacteria
MEDIUM
2017 – PhD research commenced to investigate a novel enterococcus
bacteria found in geckos
There has been no further management response
194 Source environment, population and distribution
4.1 Site tenure
Animals will be sourced from the Christmas Island National Park reptile captive breeding program
located at the Pink House within the National Park and Taronga Zoo, Sydney.
4.2 Source environment
Captive.
4.3 Demographics of source population
The captive population supports individuals within all size and age classes and has a sex ratio of
approximately 1:1 for both species.
4.4 Impact of the removal of individuals from the source population
Ensuring the viability of the captive populations of blue-tailed skinks and Lister’s geckos whilst
reintroductions attempts are occurring is critically important. One commonly used conservation tool
to help with this form of decision making are Population Viability Analyses (PVA’s). PVA’s are a tool
that allow wildlife and conservation managers to simulate extinction processes using computer
simulation models to predict the viability of populations under different management options using
demographic and stochastic parameters specified by the user (Possingham et al. 1993). A PVA was
undertaken to assist guiding suitable decisions regarding the harvesting of blue-tailed skinks from
Christmas Island unpublished data 2018). Using a conservative total of harvesting 200
animals (100 juveniles and 100 adults using an estimated 50/50 ratio) from a population with 1000
individuals (approximate current population) on a single occasion suggests there is a 0% risk of
extinction to the Christmas Island populations over a 10 year time frame. These models will be
continuingly refined over time to ensure the most up to date data is being incorporated into the
future management of these species. Overall, the risk to the source population is negligible for a one
off harvest, however the risks of multiple harvests over a sustained time period would be
considerably different and will be assessed separately.
4.5 Methods of collection and transfer
Cryptoblepharus egeriae will be held in their normal captive environment until they are ready for
relocation. During this time they will be fed invertebrates three times per week (Monday,
Wednesday, and Friday) and water will be checked daily as per the husbandry requirements of the
captive population.
On Christmas Island, four enclosures, each containing up to 30 individuals (120 total) are currently
being filled with newly recruited animals. It is anticipated that by the release date (Jan-June 2019)
these animals will be 1-18 months age. The remaining 30 animals will be harvested from young
‘overflow’ enclosures. Each enclosure will be checked for disease one, six and twelve weeks before
departure. If disease is detected in any enclosure within 12 weeks prior to departure, it will not be
included.
At Taronga Zoo, up to 30 individuals will be held in 6 enclosures in a quarantined room in
preparation for release. These will contain mostly juvenile to sub-adult individuals that have been
harvested from across the breeding colony to capture maximal genetic diversity. Each enclosure
will be under health surveillance, with physical examinations and disease checks to be undertaken
20by zoo veterinarians and skilled and trained keeping staff in the months prior to release, with a
thorough examination within two weeks of departure.
Up to 150 C. egeriae will be selected from the Christmas Island captive population and the Taronga
Zoo captive population for introduction to the Cocos (Keeling) Islands (total of up to 300 animals).
Prior to transport all animals will be individually toe-clipped using approved procedures consistent
with the Australian Society of Herpetologists (Appendix C).
On the day of departure C. egeriae will be transferred to Sistema 400 ml hard plastic ‘Click-Clack’
boxes (with air holes) (Figure 1), containing slightly moistened tissues, up to 2 lizards per box.
These plastic boxes will be inside a large insulated box to maintain the temperature if travelling in
air conditioning.
Figure 1: Sistema transport box
From Sydney to Perth (a Thursday flight), Perth to Cocos (a Friday flight) – C. egeriae will be
transported to the airport by road accompanied by Taronga staff member. Estimated time in a
vehicle is up to 1 hour to Sydney airport. Flight time is approximately 5 hours. Animals will be held
overnight in Perth where they will be visually checked by the Taronga staff member. The following
morning, animals will be transported back to Perth airport by vehicle (10 minutes). There is a risk
that the flight from Perth to Cocos will be delayed by more than 24 hrs. If this eventuates the
animals will be transported to Perth Zoo, housed in a quarantine facility in large containers, fed and
given water.
From Christmas Island to Cocos (a Tuesday flight) - C. egeriae will be transported to the airport by
road accompanied by CINP staff. Estimated time in vehicle is 10 minutes. There is a risk that the
flight from Christmas Island to Cocos will be delayed by more than 8 hrs. If this eventuates the
animals will be returned to their original enclosure until a recovery flight is scheduled.
Both transfers will occur on the same week. Animals will be transported by aircraft as cargo in a
pressurised hold. A CINP or Taronga staff member will travel on the respective flights with the
animals. Estimated time on the aircraft is 2 hours Christmas Island to Cocos (CINP) or up to 6 Perth
to Cocos (Taronga).
215 Holding site conditions
5.1 Site tenure
The staging area will be located at the Pulu Keeling National Park (PKNP) office on West Island under
the direction of CINP and PKNP staff and Taronga staff.
5.2 Holding site environment
On arrival to the Cocos (Keeling) Islands, C. egeriae will be transferred from the airport to the PKNP
office where they will be given a visual health check by experience Taronga and/or CINP staff.
Animals from Christmas Island (Tuesday) will be moved into larger holding tubs in groups of up to
20 with a small amount of habitat, provided with water and food and held overnight (Figure 2). In
the larger holding tubs, C. egeriae will be transported by small boat to the destination island. Animals
from Taronga will be transported in their original holding containers directly to the destination
island by boat. Estimated time on the boat is 30 mins.
Figure 2: Large holding tub
5.3 Species reproduction in captivity
Captive breeding of C. egeriae will only be undertaken as part of the existing captive breeding
program on Christmas Island and at Taronga Zoo as per the genetic management plan. Animals will
not be bred in captivity at the holding site.
5.4 Managing known and potential threats
N/A in the holding site.
226 Host environment
6.1 Site tenure and level of conservation protection
Pulu Blan and Pulu Kembang is Commonwealth land managed in trust by the Cocos (Keeling) Shire
Council (CKSC). Land ownership will not change with the introduction of C. egeriae and the
responsibility for future land management will remain with CKSC. It is possible that long-term
invasive species control may be transferred to Parks Australia depending on discussions with CKSC.
An agreement with CKSC may be developed to outline each party’s responsibility.
6.2 Host environment
The Cocos (Keeling) Islands are located 900km west of Christmas Island (Woodroffe & Berry 1994).
They are marginally further south and have a very similar climate profile to Christmas Island with the
major difference being that Cocos tends to have slightly less distinct wet-dry seasons with a peak of
250mm in April and minimum of 82mm in October, while Christmas Island (airport) has a peak of
343mm in February and minimum of 42.2 in August.
Table 11: Christmas Island/Cocos climate comparisons
Location Annual mean Annual mean Annual mean Years active Elevation above
rainfall (mm) maximum (°C) minimum (°C) sea level (m)
CI Airport 2199.4 27.4 22.6 1972-2018 261
CI Rocky point 1923.6 30.2 24.3 1901-1973 17
Cocos West Island 1983.1 29.1 24.6 1901-2018 3
Mean rainfall (mm)
400
350
300
250
200
150
100
50
0
CI Rocky Point Christmas Island Airport Cocos West Island
Figure 3: Monthly mean rainfall (mm) for comparison sites
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