It is difficult to identify specific management practices to avoid adverse impacts on the Christmas Island shrew due to the lack of information on the species. Many of the Actions outlined above are designed to determine specific management practices. Until these have been determined, the broad interim management practices below should be adopted to minimise potential further declines:
No removal of primary plateau rainforest within Christmas Island National Park;
Implementation of the Invasive Ants on Christmas Island Action Plan;
Continuation of liaison with AQIS and WAQIS to ensure tight quarantine controls to prevent the accidental introduction of new diseases and exotic pests;
Feral Cat and Black Rat control programs within primary plateau and terrace rainforest;
Maintenance of existing habitat quality of primary rainforest through strategies to minimise spread of exotic weeds following the Weed Management Strategy (Hart 1998); and
Adoption of strategy to avoid wildfires within potential shrew habitat.
Removal of any primary plateau and terrace rainforest could result in a significant impact on the Christmas Island shrew and should be referred to the Commonwealth Environment Minister under the EPBC Act. Removal of primary plateau and terrace rainforest on vacant crown land or leasehold land should not occur without intensive targeted surveys for the Christmas Island Shrew (see Appendix 1).
PART E: DURATION AND COSTS
Stage 1 – Costs of actions prior to location of extant populations
# = The cost of Action 2 is dependent on the number of years taken to locate extant populations and fully determine its distribution; * = Costs covered by Parks Australia North core duties.
Stage 2 - Alternative costs if extant populations found in Year 1
# = Depending on the year of location of extant populations; ¥ = This cost is assuming no reintroduction of captive shrews into the wild; * = Costs covered by Parks Australia North core duties.
Resource Allocation
The cost estimates are dependent on the year of location of extant shrew populations. Resources have been allocated for the full five years to conduct surveys to locate shrew populations over one month periods in the wet and dry seasons of each year.
Some of the actions outlined (e.g. Actions 4) in this Plan are identified in the Christmas Island National Park Plan of Management (Commonwealth of Australia 2002), the strategic nature conservation document for the island, as broader actions necessary for the maintenance of fauna biodiversity on the island. Similarly, in this Plan some of the actions recommended (e.g. Action 4) correspond with those identified in other recovery (e.g. Abbott’s Booby and Christmas Island Hawk-Owl) and action plans (e.g. Garnett & Crowley 2000). Consequently, opportunities exist for sharing resources, and a co-ordinated strategy to implement Recovery Plans for all threatened Christmas Island fauna requires investigation.
A number of Actions are already ongoing (e.g. Action 3, 4 and 9) and may be considered as core duties of PAN.
The establishment of captive breeding populations could be in association with the establishment of captive populations of critically endangered endemic avifauna in mainland zoos (Garnett & Crowley 2000). This strategy would reduce transportation costs (e.g. for release back into the wild) and quarantine procedures to ensure non-exposure to potentially fatal diseases. Alternatively, a captive breeding population could be established on Christmas Island under the guidance of PAN staff and used to aid in interpretation and community awareness programs.
Following the location of extant populations of the shrew, research is required in the same year and subsequent year over the wet and dry seasons, to identify and describe habitat critical to survival (in terms of foraging, breeding and sheltering) and threatening processes. Effective management of the located shrew populations will be ongoing and encompass both management practices covered as core PAN duties, and specialist actions that will only be identified following research into the shrew’s ecology.
The community awareness program will involve the preparation of an informative brochure that can be widely distributed amongst island residents. The other aspect of this program involves information sessions that can be given by PAN staff as part of an overall awareness program on the value of the endemic Christmas Island fauna.
Acknowledgements
Special thanks to the following people who greatly assisted with the preparation of this recovery plan. Joe Benshemesh, Luke Hogan, Jens Jacob, Lindy Lumsden, Paul Meek, Ross Meggs, Greg Richards and Peter Robertson provided advice on additional survey techniques to locate the shrew. Jeff Tranter and Peter Goh provided details on the 1985 individuals located. Sarah Brown, Marieke Lettink and Terry Reardon provided advice on the genetics action. David Boughey, Mick Jeffery and Jeff Tranter provided information on current development proposals on Christmas Island. David Armstrong and Gert Skipper provided valuable information on the establishment of captive breeding populations of small mammals. Jeff Tranter prepared Figure 1. Brigitta Wimmer provided advice on useful contacts and report preparation. Rebecca Hall, Mick Jeffery, Lindy Lumsden, Paul Meek, Jeff Tranter and Brigitta Wimmer provided valuable comments on an earlier draft of the recovery plan.
References
Andrews, C.W. 1900. A Monograph of Christmas Island (Indian Ocean). British Museum of Natural History, London.
Andrews, C.W. 1909. On the fauna of Christmas Island. Proceedings of Zoological Society, London 1909, 101-103.
Caughley, G. & Sinclair, A.R.E. 1994. Wildlife Ecology and Management. Blackwell Scientific Publications, Boston.
Churchfield, S., Barber, J. & Quinn, C. 2000. A new survey method for Water Shrews (Neomys fodiens) using baited tubes. Mammal Review 30, 249-254.
Cogger, H. & Sadlier, R. 1981. The terrestrial reptiles of Christmas Island, Indian Ocean. Report to Australian National Parks and Wildlife Service, Canberra. Australian Museum, Sydney.
Cogger, H. & Sadlier, R. 2001. The terrestrial reptiles of Christmas Island – a reappraisal of their status. Report to Parks Australia North – Christmas Island. Australian Museum, Sydney.
Commonwealth of Australia. 2002. Christmas Island National Park Management Plan. Parks Australia North, Christmas Island.
Corbet, G.B. & Hill, J.E. 1992. The mammals of the Indomalayan region: a systematic review. Oxford University Press, London.
Dickman, C. 1988. Body size, prey size, and community structure in insectivorous mammals. Ecology 69, 569-580.
Dickman, C. 1995. Diets and habitat preferences of three species of Crocidurine shrews in arid southern Africa. Journal of Zoology, London 237, 499-513.
Duncan, A., Baker, G.B. & Montgomery, N. (1999). The Action Plan for Australian Bats. Environment Australia, Canberra.
Eisenberg, J.E. 1981. The mammal radiation: an analysis of trends in evolution, adaptation and behaviour. The Athlone Press, London.
Garnett, S.T. & Crowley, G.M. 2000. The Action Plan for Australian Birds. Environment Australia, Canberra.
Goodman, S.M. & Jenkins, P.D. 1998. The insectivores of the Réserve Spéciale d’Anjanaharibe-Sud., Madagascar. Fieldiana Zoology 90, 139-161.
Haim, A., Rozenfeld, A. & Izhaki, I. 1997. Post-fire response of shrews (Crocidura suaveolens) on Mount Carmel, Israel. Mammalia 61, 527-536.
Hart, R. 1998. Environmental weeds of Christmas Island – a management plan. Report to Parks Australia North, Christmas Island.
Hill, F.A.R. & Lill, A. 1998a. Density and total population estimates for the threatened Christmas Island Hawk-Owl Ninox natalis. Emu 98, 209-220.
Hill, F.A.R. & Lill, A. 1998b. Diet and roost site characteristics of the Christmas Island Hawk-Owl Ninox natalis. Emu 98, 227-233.
Jenkins, P.D. 1976. Variation in Eurasian shrews of the genus Crocidura (Insectivora: Soricidae). Bulletin of the British Museum of Natural History (Zoology) 30, 271-309.
Jenkins, P.D. 1982. A discussion of Malayan and Indonesian shrews of the genus Crocidura (Insectivora: Soricidae). Zoologische Mededelingen 56, 267-279.
Jiang, X-L. & Hoffmann, R.S. 2001. A revision of the white-toothed shrews (Crocidura) of southern China. Journal of Mammalogy 82, 1059-1079.
Lister, J.J. (1888). On the natural history of Christmas Island in the Indian Ocean. Proceedings of the Zoological Society 1888, 512-513.
Lumsden, L. & Cherry, K. 1997. Report on a preliminary investigation of the Christmas Island Pipistrelle Pipistrellus murrayi, in June – July 1994. Arthur Rylah Institute for Environmental Research, Heidelberg, Victoria.
Lumsden, L., Silins, J. & Schulz, M. 1999. Population dynamics and ecology of the Christmas Island Pipistrelle Pipistrellus murrayi on Christmas Island. Report for Parks Australia North – Christmas Island. Arthur Rylah Institute for Environmental Research, Heidelberg, Victoria.
Meek, P.D. 2000. The decline and current status of the Christmas Island Shrew Crocidura attenuata trichura on Christmas Island, Indian Ocean. Australian Mammalogy 22, 43-49.
Motokawa, M., Harada, M., Lin, L.K., Koyasu, K. & Hattori, S. 1997. Karyological study of the gray shrew Crocidura attenuata (Mammalia: Insectivora) from Taiwan. Zoological Studies 36, 70-73.
Motokawa, M., Suzuki, H., Harada, M., Lin, L.K., Koyasu, K. & Oda, S. 2000. Phylogenetic relationships among East Asian species of Crocidura (Mammalia: Insectivora) inferred from mitochondrial cytochrome b gene sequences. Zoological Science 17, 497-504.
Nowak, R.M. 1999. Walker’s Mammals of the World. Volume 1. Sixth edition. The John Hopkins University Press, Baltimore, USA.
Pickering, J. & Norris, C.A. 1996. New evidence concerning the extinction of the endemic murid Rattus macleari Thomas 1887, from Christmas Island, Indian Ocean. Australian Mammalogy 19, 19-25.
Querouil, S., Hutterer, R., Barriere, P., Colyn, M., Kerbis Peterhans, J. C. & Verheyen, E. 2001. Phylogeny and evolution of African shrews (Mammalia: Soricidae) inferred from 16s rRNA sequences. Molecular Phylogenetic Evolution 20, 185-195.
Ruedi, M. & Vogel, P. 1995. Chromosomal evolution and zoogeographic origin of southeast Asian shrews (genus Crocidura). Experientia 51, 174-178.
Ruedi, M., Auberson, M. & Savolainen, V. 1998. Biogeography of Sulawesian shrews: testing for their origin with a parametric bootstrap on molecular data. Molecular Phylogenetic Evolution 9, 567-571.
Ruedi, M., Maddalena, T., Yong, H.S. & Vogel, P. 1990. The Crocidura fuliginosa species complex (Mammalia: Insectivora) in Peninsular Malaysia: biological, karyological and genetical evidence. Biochemical Systematic Ecology 18, 573-581.
Rumpff, H. 1992. Distribution, population structure and ecological behaviour of the introduced Southeast Asian Wolf Snake Lycodon aulicus capucinus on Christmas Island, Indian Ocean. Report to Australian National Parks and Wildlife Service, Canberra.
Suckling, G.C. 1978. A hair sampling tube for the detection of small mammals in trees. Australian Wildlife Research 5, 249-252.
Thomas, O. 1888. On the mammals of Christmas Island. Proceedings of Zoological Society, London 1888, 532-534.
Tidemann, C.R. 1988. Survey of the terrestrial mammals on Christmas Island (Indian Ocean). Report to Australian National Parks and Wildlife Service, Canberra.
Tidemann, C.R., Yorkston, H.D. & Russack, A.J. 1994. The diet of cats, Felis catus, on Christmas Island, Indian Ocean. Wildlife Research 21, 279-286.
Wolsan, M. & Hutterer, R. 1998. A list of the living species of shrews. Pp. 425-448. In: Wojcik, J. M. & Wolsan, M. (eds.) Evolution of Shrews. Mammal Research Institute, Polish Academy of Sciences, Poland.
APPENDIX 1: TARGETED SURVEY
Objective: To locate extant populations of the Christmas Island Shrew.
Personnel:
The survey must be undertaken by a consultant with either previous field survey experience of Crocidurine shrews or extensive expertise using a wide range of survey techniques in targeted surveys for small mammal species within Australia. The consultant must have good lateral thought with the ability to use adaptive targeted survey strategies.
Duration:
To be conducted for one month sample periods in both the dry and wet seasons of each year for the five-year timeframe of the Recovery Plan or until extant populations have been located and the distribution fully assessed.
Approach:
Following from the survey of Meek (2000), a stratified survey across all primary plateau and terrace rainforest communities and in ecotones between these and other vegetation communities should be undertaken using a variety of additional or modified techniques.
Site Selection:
Sites should be selected in primary plateau and terrace rainforest at 2km2 intervals across the island. All sites need to be outside of crazy ant infestations or sites treated by aerial baiting in September 2002. Initially it is recommended survey effort be concentrated on the western section of the island (west of Margaret Beaches on the north coast and South Point on the south coast), with the following areas to be investigated as high priority:
- 1985 shrew localities: plateau rainforest adjacent to the Shrine in LB4 and terrace rainforest at No 1 Dale.
- plateau rainforest linking the two 1985 localities, including Ferguson, Murray, Bean and Camp Hill areas.
- terrace rainforest between North West Point and Egeria Point.
- terrace and plateau rainforest from Jones Point east to The Blowholes.
- terrace and plateau rainforest along north coast from North West Point east to the eastern end of Margaret Beaches.
Logistically it is not feasible to obtain coverage of the entire island on each visit, both in terms of distances involved and the requirement to check traps frequently. Instead, it is recommended that a number of contiguous 2km2 areas be surveyed simultaneously.
For each 2km2 sector, the following land features be selected on different survey visits:
a. Coastal 2km2 areas:
- Ecotone of terrace rainforest and coastal vegetation or shoreline.
- Terrace rainforest on ecotone with inland cliffs and scree slopes.
- Primary rainforest on ecotone with inland cliffs and scree slopes.
b. Inland 2km2 areas:
- Primary rainforest with rock outcropping.
- Primary rainforest without rock outcropping.
The location of each site must be permanently marked and accurate coordinates recorded using a GPS to enable revisits.
Survey Timing and Duration:
Where possible, survey visits to be timed to coincide with reduced land crab activity (e.g. Robber Crab moulting period in March/April). Each site to be sampled for seven consecutive days, which is longer than normally necessary to reach asymptotes in species accumulation curves for small insectivores, such as shrews (after Goodman & Jenkins 1998).
Survey Techniques:
Survey techniques typically used to detect and capture shrews are pitfall trapping and live trapping using a variety of trap designs, such as Sherman, Longworth and Elliott traps. Standard techniques are difficult to use on the island due to the problem of crab interference. All survey methods must take crab interference into consideration.
Survey techniques listed below are to be used at all standard sites selected. Additionally, the consultant must have the option to use an adaptive survey strategy trialling new techniques or modifications to the following listed techniques. Additional strategies could include the use of waterproofed infra-red video camera systems at permanent feeding stations, both on the ground and in the canopy (e.g. following the field-tested design of Ross Meggs; Faunatech, P.O. Box 1655, Bairnsdale, Victoria, 3875; goodgear@faunatech.com.au); automated playback that would enable sampling a number of localities simultaneously; and use of shrew pheromone from SE Asian shrews as an attractant. Where time permits, opportunistic sampling using the standard survey techniques listed below at additional locations is to be encouraged.
Pitfall Trapping
Pitfall trapping is a common technique for locating Crocidurine shrews in the Northern Hemisphere and Asia. Lister (1888) recorded the capture of three individuals in pitfall traps on the island, but did not specify the nature of the traps used. Meek (2000) used pitfall traplines (12 pits along a 25 m line; diameter 250 mm and 80 mm) at three sites in the Dales - Winifred Beach area. Rolls of rigid underground powerline cable cover (300 mm X 4 mm) were used as a drift fence. Segments of PVC tubing (100 mm X 40 mm) were placed at the bottom of pits to act as refuge sites for captured animals from Robber Crab predation.
Establish ten pitfall traps of PVC tubing (maximum diameter: 80mm, minimum depth: 250mm, each trap capped by heavy duty wire mesh (e.g. steel) at a distance of 5m apart with the upper rims flush with ground level. Drift fence similar to that used by Meek (2000) or utilise mobile crab fences developed by PAN (M. Jeffrey, pers. comm.). The small diameter tubing coupled with the wire mesh capping of a spacing to exclude Robber Crabs and the majority of other crabs. This wire mesh is to be hooked into place at the top of each pit. Each pitfall trap to have non-absorbent cotton wool or coconut fibre to be placed in the base to serve as shelter. Additionally, each pitfall trap to have a securely fitting lid for when pits not in use.
Live Trapping
Lines of twenty-five Longworth/Sherman/or finely tuned Elliott traps be established at intervals of 10m on the ground (after Haim et al. 1997), with an additional 10 traps sited in trees (including canopy) or rock faces, preferably in proximity to epiphytes. Traps to be baited with a range of baits including: rolled oats, peanut butter and sunflower seeds, as well as a presumed shrew specific mixture of ikan billis (fish) soup powder, flour and water (after Meek 2000). Each trap to be surrounded by guyed or tied-down wire mesh of sufficient mesh spacing to allow shrew passage but to prevent Robber Crab interference. To provide protection against high temperatures non-absorbent cotton wool or other insulative material must be placed in each trap. Traps must be checked twice daily (early morning and late afternoon) to minimise shrew mortality.
Call Playback
Earlier naturalists commented on the short shrill squeak of the shrew commonly heard throughout the island (Lister 1888, Andrews 1900). No information is provided as to the time of day or conditions when calls were heard. At each site, conduct two call playback sessions: within two hours after dawn and within two hours following dusk. Each session to consist of a thirty minute listening period, followed by a ten-minute period of playing the call of related Crocidura shrews, followed by another thirty minute listening period.
Active Searching
The shrew was recorded living in holes in rocks and roots of trees (Andrews 1900). At each site, spend one person hour actively searching under rocks, ground debris and at the base of trees with the aid of a rake and gemmie bar.
Artificial Habitat and Nest Burrows
At each site, position ten sheets of artificial habitat (such as corrugated iron sheeting) flush with the ground adjacent to the base of trees or amongst rocks. These sheets to be regularly checked.
At each site, place ten artificial nest burrows (made of two layers of PVC tubing) at the base of canopy trees, following the same design and dimensions as used for the Earless Dragon Tympanocryptis lineata pinguicolla (designed by P. Robertson, Wildlife Profiles P/L, P.O. Box 500 Heidelberg, Victoria 3084; wildlife.profiles@bigpond.com).
Hair Funnels and Hair Tubes
Shrews readily investigate novel objects and frequently defaecate on the inside of such objects (Churchfield et al. 2000). At each site, locate five hair funnels (Faunatech) and five hair tubes (following the design of Suckling 1978) 20 m apart on the ground, and five hair funnels and five hair tubes in trees (including in the canopy) or on rock faces adjacent to epiphytes. The hair funnels/hair tubes are to be baited with the same mixture as for Longworth/Elliott traps. Each trap to be surrounded by guyed or tied-down wire mesh of sufficient mesh spacing to allow shrew passage, but to prevent Robber Crab interference. These traps to be regularly checked for hairs and scats.
Epiphyte and Loose Bark Search
There is a possibility that the shrew uses epiphytes as shelter sites (Meek 2000). At each site, where feasible, search epiphyte clumps on the trunk and in the canopy, and strips of loose bark on trunks and logs for sheltering shrews. This search to be conducted by manual light beating of the clump/bark with the aim of disturbing sheltering shrews.
Predator Gut and Scat Analysis
At each site, any predator scats and regurgitations be collected for analysis after each survey period. Additionally, encourage Parks Australia North staff to retain and be trained to identify the gut contents of all feral cats killed during control programs and randomly.
Both on site and elsewhere, locate nests of the Nankeen Kestrel Falco cenchroides, Christmas Island Goshawk Accipiter fasciatus natalis and Christmas Island Hawk-Owl Ninox natalis, for the collection and analysis of regurgitated and discarded material.