National recovery plan for the Christmas Island Pipistrelle Pipistrellus murrayi
Prepared by Martin Schulz and Linda F. Lumsden
Department of the Environment and Heritage, 2004
ISBN 0 642 55012 3
Part D: Objectives, criteria and actions
Recovery Objectives and Timelines
The overall objectives of this recovery plan are to:
- determine the threatening processes responsible for the decline in the species,
- maximise the opportunity for the viability of the species in the wild, and
- clarify its taxonomic status,
- evaluate the Christmas Island Pipistrelle's conservation status.
Specific objectives for the five years of this Recovery Plan are listed below. Note that these objectives are not listed in order of priority.
- Objective 1: To assess current population and distribution trends of the Christmas Island Pipistrelle.
- Objective 2: To determine the roosting requirements of the Christmas Island Pipistrelle, including seasonal and distributional differences.
- Objective 3: To assess the potential for the Common Wolf Snake to prey on bats in roosts and if it is considered that they impact on pipistrelles, devise management actions to reduce predation.
- Objective 4: To assess the impact of the Nankeen Kestrel and if found to predate on pipistrelles, devise management actions to reduce impact.
- Objective 5: To identify primary foraging site characteristics in the dry and wet seasons, especially away from ecotones and roadways, within extensive tracts of primary rainforest.
- Objective 6: To examine dietary specialisation as a contributing factor in the species' decline.
- Objective 7: To clarify the taxonomic status of the Christmas Island Pipistrelle.
- Objective 8: To continue active management for the control of Yellow Crazy Ant supercolonies.
- Objective 9: To increase protection of known and potential habitat outside the Christmas Island National Park.
- Objective 10: To assess the potential impact on the Christmas Island Pipistrelle of phosphate stockpile removal within and abutting the Christmas Island National Park.
- Objective 11: To establish guidelines to reduce vehicle-related mortality along roads passing through important foraging areas.
- Objective 12: To review the conservation status of the species.
Performance Criteria
Performance Criteria listed below match the corresponding Objectives and are to be achieved within the five-year duration of the plan:
- Criterion 1: The current status of the population and distribution trends in the species are determined.
- Criterion 2: Roosting requirements are characterised, including maternity and non-breeding roosts. Roosting requirements in the core of the species range are compared with those at the eastern limit of the range, and the impact of Yellow Crazy Ant supercolonies on roosting habitat is determined.
- Criterion 3: The impact of the Common Wolf Snake on roosting bats is determined and management actions established to reduce such impacts where they occur.
- Criterion 4: The impact of the Nankeen Kestrel on pipistrelles is determined and management actions established to reduce such impacts where they occur.
- Criterion 5: Primary foraging habitat is identified away from forest ecotones and roadways.
- Criterion 6: The diet of the species is determined in both the wet and dry season and compared to prey availability.
- Criterion 7: Taxonomic status of the Christmas Island Pipistrelle is resolved.
- Criterion 8: All supercolonies of the Yellow Crazy Ant are eliminated and ongoing management undertaken to ensure no subsequent re-infestation.
- Criterion 9: Protection of known or potential habitat is increased outside the Christmas Island National Park.
- Criterion 10: An assessment of the impacts on the Christmas Island Pipistrelle of proposed phosphate stockpile removal within and abutting the Christmas Island National Park has been conducted.
- Criterion 11: Guidelines have been established and implemented to reduce vehicle-related mortality.
- Criterion 12: The conservation status of the species has been reviewed.
Evaluation of Performance
The plan's performance is to be reviewed by an Island Recovery Team as proposed for avifauna by Garnett & Crowley (2000). This recovery team is to be established with the primary objective of developing and implementing island-wide conservation management and recovery plans, including for the Christmas Island Pipistrelle. The Recovery Team is to review and evaluate progress with respect to this Recovery Plan annually over the five-year period. This recovery team should comprise:
- on-island representatives, including Parks Australia North staff, a Shire of Christmas Island representative, and other local members as deemed appropriate, and
- off-island representatives, including, a scientific member of the Crazy Ant Steering Committee and one or two leading bat ecologists with first-hand knowledge of the island's ecology.
Actions
The EPBC Act requires that a Recovery Plan must provide for research and management actions necessary to halt the decline of, and support the recovery of, listed threatened species or ecological communities to maximise these species/communities chances of long-term survival. Therefore, some of the actions identified within this Plan are research actions that are essential to identify threatening processes and the cause of the decline and range contraction in the Christmas Island Pipistrelle.
Note: The identified actions have been divided into research and management actions and are not listed according to order of significance or impact.
A. Research and Monitoring Actions
Action 1: Assess population and distribution trends in the Christmas Island Pipistrelle and establish long-term monitoring programs (Obj. 1, 3, 4, 6, 8, 9, 10 and 11; Perf. Crit. 1, 3, 4, 6, 8, 9, 10 and 11)
Background Summary: Available evidence indicates that the species is in decline and its range is contracting westwards. As the last comprehensive study was undertaken in 1998, it is critical that a reassessment of the current status and distribution of the species is undertaken, and that changes in activity levels in areas that were formerly infested with the Yellow Crazy Ant supercolonies are investigated. A long-term monitoring program is required to assess the recovery of the species.
Threatening Process: Various, particularly threatening processes contributing to a decline and westward range contraction in the species.
Actions:
- 1a) Using the same methodology at the same sites sampled by Lumsden et al. (1999) investigate whether the continuing trend of westward range contraction is still occurring. Conduct sampling in May-June of Year 1 using the sampling technique outlined in Appendix One. Undertake repeat sampling using the same techniques in May-June of Year 5.
- 1b) Using comparable techniques to Lumsden et al. (1999), determine differences in activity levels at localities supporting high or moderate bat activity that have been or currently are infested with Yellow Crazy Ant supercolonies, as outlined in Appendix One. This monitoring study needs to be conducted in May-June for direct comparison with the pre- or early infestation results presented in Lumsden et al. (1999). It should include the same insect sampling techniques (Appendix One). Conduct repeat sampling using the same techniques in May-June of Year 5.
- 1c) Establish a Christmas Island Pipistrelle database to record casual night-time observations, daylight foraging observations, predation incidences, sightings away from ecotones and roads, and other information that would be valuable in the context of this Recovery Plan. Such a database could provide supplementary baseline information on critical components of the species' ecology.
- 1d) Establish an island-wide monitoring program to determine long-term population and distributional trends that can be undertaken by Parks Australia North personnel using an easily repeatable set of criteria as recommended in Appendix Two. As part of this action: i) purchase equipment required to undertake long-term monitoring (Appendix Two); ii) establish protocols for the analysis of each sampling session in consultation with experienced bat ecologists and iii) establish a database to ensure the accessibility of monitoring results in the advent of staff turnover.
Action 2: Determine roosting requirements, investigating seasonal and distributional differences (Obj. 2, 3, 9 and 10; Perf. Crit. 2, 3, 9 and 10)
Background Summary: Only limited information is available on roosting requirements of the Christmas Island Pipistrelle, and this is all from within the dry season. No information is available on roosting requirements during the birthing and lactation periods in the late dry and wet season. Many insectivorous bats that utilise a range of diurnal roosts outside the breeding season display more specific maternity roost site selection, as a function of thermal properties, and protection from predators and adverse conditions (e.g. Kunz & Lumsden 2003). Roosts used during this period, particularly maternity sites which may be a limiting factor, are critical to the long-term maintenance of the population. There is also no information on roosts used at the eastern limit of the species' range. The identification of roosts in this area and a comparison of roost selection between the core of the species' distribution and the eastern edge may assist in understanding the reasons behind the contraction in the distribution of the species. The loss of roost suitability may be an important contributing factor to its decline and range contraction. The provision of artificial predator-proofed roosts may assist in re-colonisation of forested areas in the east that were formerly inhabited.
Threatening Process: Yellow Crazy Ant, introduced predators and possibly as yet unidentified threatening processes.
Actions:
- 2a) In Year 1, determine the roosting requirements of males and females, during both the non-breeding and breeding (i.e. early wet) seasons. Compare roosts used with available roosting habitat to investigate roost site selection. Sample both in the core of the species distribution (i.e. in the western section) and along the eastern edge of its current range. In the east, target areas that supported bat activity in the 1998 survey (Appendix Three ). Repeat this sampling in Year 5.
- 2b) Locate diurnal roosts in areas previously affected by Yellow Crazy Ant supercolonies and in unaffected areas, and compare these results with the roosts located by Lumsden et al. (1999) to identify potential shifts in roost structure usage. To be comparable sampling should be undertaken in May-June of Year 1, and should include the area sampled in 1998 (Appendix One). Conduct repeat sampling using the same techniques in May-June in Year 5.
- 2c) In sections of rainforest where roost sites are determined to be limiting, or no longer suitable, trial artificial roosts based on roost characteristics as determined by Action 2a. If required, these roosts must be erected in such a manner as to avoid access by Robber Crabs (due to known destructive interference with artificially erected structures), and the potential predators Yellow Crazy Ant, Black Rat and Common Wolf Snake.
Action 3: Determine the impact of the Common Wolf Snake on roosts, and if considered to impact on pipistrelles, develop management actions to reduce the predation risk (Obj. 2 and 3; Perf. Crit. 2 and 3)
Background Summary: The westward contraction in the distribution of the Christmas Island Pipistrelle corresponds with the westward expansion of the Common Wolf Snake. However, it is currently unknown whether this snake is able to access pipistrelle roosts within primary rainforest.
Threatening Process: Introduced predator.
Actions:
- 3a) Establish and maintain a database using the CIGIS for Common Wolf Snake records, with every sighting away from the Settlement, Grants Well, and the Christmas Island Research and Education Station areas to be recorded. Such a database could provide important baseline information on the distribution of this species.
- 3b) Conduct a survey for the Common Wolf Snake in the central section of the island to document the range of this species outside known populations using spotlighting and active area search techniques. The survey is to include dry and wet season sampling periods and investigate areas away from roads and dwellings. Investigate the gut contents of all snakes encountered.
- 3c) Investigate the ability of the Common Wolf Snake to access simulated roosts under exfoliating bark and strangler figs on rainforest tree trunks in captivity.
- 3d) If, based on the investigations in 3b and 3c, it is considered that the Wolf Snake is impacting on bats within their roosts, devise and implement appropriate management actions.
Action 4: Determine the impact of the Nankeen Kestrel, and if found to prey on pipistrelles, develop management actions to reduce the impact (Obj. 4; Perf. Crit. 4).
Background Summary: The absence of daytime foraging in recent years corresponds to an increase in the population of the naturalised Nankeen Kestrel.
Threatening Process: Naturalised predators.
Actions:
- 4a) Establish and maintain a Nankeen Kestrel sightings database using the CIGIS with PAN staff (and members of the public) recording sightings of this species. Such a database will provide important baseline information for the location of nests (see Action 4b).
- 4b) Conduct dusk watches at sites of high bat activity, coupled with a dietary study of prey remains found at nests to determine predation rates by the Nankeen Kestrel. This action is to be concentrated within the current range of the pipistrelle. Dusk watches are to be undertaken in the dry and wet seasons.
- 4c) Evaluate the importance of Nankeen Kestrel control if this species is determined a key predator of the Christmas Island Pipistrelle.
Action 5: Identify primary foraging sites away from ecotones and roads (Obj. 1, 5, 6, 9 and 10; Perf. Crit. 1, 5, 6, 9 and 10)
Background Summary: Primary foraging habitats have been poorly described for the species in rainforest away from roads, ecotones and drill lines. Many of the drill lines bulldozed in the 1960s have become overgrown. Bats were commonly observed using drill lines in 1984 (Tidemann 1985). However, by 1998 many drill lines were ill-defined and provided little 'edge' for this edge specialist to target (Lumsden et al. 1999). The importance of open drill lines to the pipistrelle requires understanding in a landscape context. Therefore, it is important to characterise foraging habitat used by pipistrelles away from classic edges, such as roads and ecotones.
Threatening Process: Habitat alteration and habitat loss.
Actions:
- 5a) Identify and characterise foraging areas utilised by the Christmas Island Pipistrelle away from roads, ecotones and defined drill lines in primary rainforest. This investigation should include examining the importance of the crown of the rainforest canopy as a large 'edge' surface; the importance of emergents and natural openings, such as resulting from storm damage; and the importance of 'within-canopy' foraging. This action is to be undertaken in the dry and wet season sampling periods.
Action 6: Investigate dietary specialisation as a contributing factor to the current status of Christmas Island Pipistrelle (Obj. 5 and 6; Perf. Crit. 5 and 6)
Background Summary: The Christmas Island Pipistrelle forages on a variety of flying insects caught on the wing. However, it is not known whether the species is a specialist or generalist feeder. Changes in the primary rainforest ecosystem (e.g. through Yellow Crazy Ant supercolony infestation) may have altered the availability of prey items. If this resulted in prey being limited, it would impact on the status of the pipistrelle.
Threatening Process: Currently unknown, evidence suggests Yellow Crazy Ant supercolony infestation may have altered primary rainforest insect populations in terms of diversity and abundance.
Actions:
- 6a) Identify the diet of the pipistrelle in the dry and wet seasons, by analysing droppings collected from individuals caught in harp traps.
- 6b) Compare diet with prey availability at identified foraging areas (determined by feeding buzzes recorded using a bat detector) to identify the degree of dietary specialisation in the species.
Action 7: Clarify the taxonomic status of the Christmas Island Pipistrelle (Obj. 7; Perf. Crit. 7)
Background Summary: The taxonomic status of the Christmas Island Pipistrelle requires clarification.
Actions:
- 7a) A genetic study of the Christmas Island Pipistrelle and closely related species, using samples obtained from dry or ethanol preserved museum specimens. Such a study would require genetic material of the Christmas Island Pipistrelle, two Australian and two Southeast Asian Pipistrellus species, including P. tenuis. This investigation is recommended to be undertaken by, or in conjunction with, an experienced bat taxonomist.
B. Management Actions
Action 8: Continue active management for the control of Yellow Crazy Ant supercolonies (Obj. 8 and 9; Perf. Crit. 8 and 9)
Background Summary: The long-term viability of the Christmas Island Pipistrelle may be threatened by the presence and spread of Yellow Crazy Ant supercolonies. Parks Australia North in consultation with the Crazy Ant Steering Committee is undertaking surveys for the presence of Yellow Crazy Ant supercolonies in both infested and unaffected areas following a successful aerial baiting campaign. All supercolonies encountered will be eliminated through ground-baiting techniques where possible.
Threatening Process: Yellow Crazy Ant.
Actions:
- 8a) It is important that a program of ongoing monitoring and surveillance be established to detect future supercolony formation and undertake appropriate remedial actions.
- 8b) The known roosting areas in the far west of the island (especially the Winifred Beach Tk area, see Figure 3) should be intensively monitored on a regular basis so that any future outbreaks can be controlled immediately.
Action 9: Increased protection of known and potential habitat outside the National Park (Obj. 1, 2, 3, 4, 5, 8, 9, 10 and 11; Perf. Crit. 1, 2, 3, 4, 5, 8, 9, 10 and 11)
Background Summary: The Christmas Island Pipistrelle was formerly widespread and common throughout the island. Extensive loss of habitat through clearfelling for phosphate mining has resulted in a reduction of suitable habitat available, particularly for diurnal and maternity roosting purposes. Some areas identified as having high and moderate bat activity in 1998 occurred outside or along roads delineating the boundary of the Christmas Island National Park (Lumsden et al. 1999):
- Off Dales Road, 0.3 km west of Winifred Beach Track turnoff (10o28'30", 105o34'16") (Site 7),
- Winifred Beach Track, 0.1 km south of Dales Road (10o28'40", 105o34'25") (Site 21),
- ML 106 area, on track heading west, 0.6 km from Blowholes Road (10o30'24", 105o38'35") (Site 34).
Threatening Process: Habitat loss.
Actions:
- 9a) The protection of known pipistrelle foraging areas outside the Park should be a priority, for example an important foraging area is located at the start of the Winifred Beach Track (see above, from Lumsden et al. 1999; see Figure 6 ).
- 9b) In accordance with the requirements of the EPBC Act development proposals likely to have a significant impact on the Christmas Island Pipistrelle must be referred to the Commonwealth Environment Minister to determine whether approval is required under the Act. This includes actions likely to adversely affect habitat critical to the survival of the species, therefore determining whether an action is likely to have a significant impact needs to include consideration of suitable roosting and foraging habitat. All areas of primary rainforest and advanced secondary rainforest regrowth (e.g. > 30 years old) require a detailed appraisal of the vegetation to determine its potential to provide roosting sites. This is to be based on the current knowledge of roosting habitat as outlined in Lumsden et al. (1999), or further information as it comes to hand. Areas supporting primary rainforest, or secondary rainforest regrowth of any age, need to be appraised for foraging habitat, by sampling with bat detectors, using the technique outlined in Appendix One.
Action 10: Assess the impact of phosphate stockpile removal on the Christmas Island Pipistrelle (Obj. 9 and 10; Perf. Crit. 9 and 10)
Background Summary: The proposed removal of phosphate stockpiles within and abutting the Christmas Island National Park may adversely affect foraging, roosting and commuting habitat.
Threatening Process: Habitat loss.
Actions:
- 10a) Areas proposed for phosphate stockpile removal, other than those previously approved under the Environment Protection (Impact of Proposals) Act 1974, to be reviewed in terms of impact to the Christmas Island Pipistrelle. Any stockpiles considered to be important to Christmas Island Pipistrelles, for example, those containing known roost areas, or important foraging or commuting areas are to be protected from phosphate extraction.
Action 11: Guidelines to reduce vehicle-related mortality (Obj. 1 and 11; Perf. Crit. 1 and 11)
Background Summary: The Christmas Island Pipistrelle commonly uses roadways passing through primary rainforest and secondary rainforest regrowth for foraging and commuting purposes. This species is particularly susceptible to vehicle-related mortality due to it commonly flying close to ground level.
Threatening Process: Vehicle-related mortality.
Actions:
- 11a) Establish guidelines in consultation with the relevant affected interests to reduce the risk of night-time vehicle-related mortality on roadways traversing areas of known high and moderate bat activity.
- 11b) Upgrading of roads and construction of infrastructure along the route between the Immigration Reception and Processing Centre and the Settlement should involve minimal rainforest clearance and night-time speed restrictions should be placed along sections supporting known populations of foraging and commuting bats. The Christmas Island Shire and the Australian Federal Police should form part of consultations for any proposed changes to traffic conditions or speed limits.
Action 12: Review the conservation status of the species (Obj. 12; Perf. Crit. 12)
Background Summary: Recent evidence has indicated a continued decline in the species since the fieldwork of Lumsden et al. (1999). A summary of this information is provided in Appendix 4.
Actions:
- 12a) Determine whether recent information provides justification to elevate the conservation status of the Christmas Island Pipistrelle to Critically Endangered as defined under the EPBC Act. Specific issues to be considered include: i. it has undergone a very severe reduction in numbers, ii. its geographic distribution is very restricted indicating that it is precarious for the survival of the species, and iii. evidence suggests that the numbers will continue to decline at a very high rate.