PART A: Species information AND general requirements
5
Species
5
Conservation status
5
Taxonomy
5
Objects of the Act
5
International Obligations
5
Affected Interests
5
Role and interests of indigenous people
6
Benefits to other species/ecological communities
6
Social and economic impacts
6
PART B: DISTRIBUTION AND LOCATION
8
Distribution
8
Habitat
9
Habitat critical to the survival of the species
9
Important populations
9
PART C: KNOWN AND POTENTIAL THREATS
11
Identification of threats
11
Areas under threat
12
Populations under threat
12
PART D: OBJECTIVES, CRITERIA AND ACTIONS
13
Recovery objectives and timelines
13
Performance criteria
13
Evaluation of performance
13
Actions
14
Management Practices
16
PART E: DURATION OF RECOVERY PLAN AND ESTIMATED COSTS
17
Stage 1 - Costs of actions prior to location of extant populations
17
Stage 2 - Alternative costs if extant populations found in Year 1
17
Resource Allocation
17
ACKNOWLEDGEMENTS
18
REFERENCES
19
APPENDIX 1: TARGETED SURVEY
21
Summary
Current Status
The Christmas Island Shrew Crocidura attenuata trichura is the only member of the shrew family (Soricidae) recorded in an Australian territory. Currently this species is listed as Endangered under the Environment Protection Biodiversity Conservation Act 1999 (EPBC Act). Due to current taxonomic uncertainty the phylogenetic relationship of the Christmas Island Shrew with closely related southeast Asian taxa requires resolution.
Distribution and Location
The species was widespread and abundant on Christmas Island at the time of settlement, occurring in rainforest on both the plateau and adjacent to the shoreline. It appeared to decline rapidly, with no subsequent records after 1908. The Christmas Island Shrew was thought to be extinct until an accidental finding of two single individuals in 1985. The species has not been recorded since these sightings, despite various subsequent targeted surveys, and therefore must be considered as extremely rare and possibly extinct. Habitat requirements critical to this species survival, including the provision of foraging, shelter and breeding resources are unknown.
Known and Potential Threats
Since the Christmas Island Shrew is so poorly known in terms of its conservation ecology, no known threats have been documented. However, the dramatic decline which occurred within 20 years of human settlement, suggests direct or indirect human threat. Current potential threatening processes include direct and indirect effects of the Yellow Crazy Ant Anoplolepis gracilipes, crazy ant control measures, habitat loss, disease, habitat alteration, predation and small population size.
Recovery Plan Objectives
The Recovery Plan is to follow two stages:
Stage 1: Prior to location of extant populations.
To clarify the taxonomic status from existing museum specimens.
To assess the current status and distribution through further targeted surveys.
To develop a wildlife management program for habitat outside Christmas Island National Park
To control the abundance and spread of the crazy ant.
To implement a community awareness program that may assist in the location of previously unknown populations.
Stage 2: Subsequent to the location of extant populations.
To establish captive breeding populations from any wild populations located, pending mitigation of the threat from the crazy ant and other potential predators and competitors.
To effectively protect and manage wild populations.
To identify habitat critical to survival, including shelter, breeding and foraging habitat.
To determine and mitigate threatening processes affecting populations.
Biodiversity Benefits
Protection and maintenance of plateau and terrace rainforests will benefit other endemic rainforest-dependent species.
# = 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.
INtroduction
The Christmas Island Shrew Crocidura attenuata trichura is the only member of the shrew family (Soricidae) recorded in Australia. The genus of white-toothed shrews Crocidura, with 158 recognised species, is the most speciose of all mammalian genera (Wolsan & Hutterer 1998, Nowak 1999). The taxonomy and distribution of many members of the genera is confusing and inconclusive (Nowak 1999, Jiang & Hoffmann 2001). All members of the genus are small, with a head and body length of 40–180mm and tail length of 40–110mm and a distinctly pointed muzzle.
The Christmas Island Shrew varies from light or reddish-brown to dark slate grey in colouration, with a weight range between 4.5 and 6.0g (Meek 2000; J. Tranter, Dept Environment and Heritage, pers. comm.). It is similar in appearance and occupies a corresponding niche to small Australian carnivorous marsupials (Dasyuridae), such as planigales Planigale sp. and dunnarts Sminthopsis sp. (Eisenberg 1981).
This little animal was once extremely common all over the island and its distinctive shrill squeaks could be heard all around as one stood quietly in the rainforest (Lister 1888, Andrews 1900). By 1908 it was considered to be probably extinct with no specimen either seen or heard during a visit by Andrews (1909). It was rediscovered in 1985, with two specimens located accidentally over a period of less than one month in rainforest on the western side of the island (Meek 2000; J. Tranter, DEH, pers. comm.). Following inquiries by Meek (1998), it was reported that two specimens were encountered in 1958 during rainforest clearing operations for phosphate mining near South Point. However, since 1985, no further individuals have been recorded despite various targeted surveys across the island using a variety of techniques (e.g. Meek 2000), fauna surveys as a component of environmental assessment reports for development proposals, and during the course of field studies on other rainforest fauna. Given there are only two confirmed records over the past century, the Christmas Island shrew has to be considered as extremely rare or possibly extinct.
The most important short-term objective of the Recovery Plan is to initiate targeted field surveys to determine the current distribution and status of the Christmas Island Shrew.
Part A: Species information and general requirements
Species
Christmas Island Shrew Crocidura attenuata trichura
Conservation Status
Currently listed Endangered under the Environment Protection Biodiversity Conservation Act 1999 (EPBC Act).
Taxonomy
The taxonomic status of the Christmas Island Shrew is unclear.
It was originally regarded as “a local variety” of the southeast Asian White-toothed Shrew Crocidura fuliginosa (Dobson 1888 cited in Thomas 1888), which is widespread in southeast Asia, including Indonesia (Jenkins 1982, Corbet & Hill 1992). This was because the type specimen collected by Dobson (1888) (cited in Andrews 1900) had a tail of 80mm, 10mm longer than the head and body length of 70mm, and thickly covered with fine hairs. However, in the ten specimens collected by Andrews (1900) the tail (range: 63–75mm) was typically shorter (in one individual by 10mm) than the head and body length (range: 65–82 mm) and in only two specimens was it slightly longer. Based on the morphological characteristics, Jenkins (1976) described it as a subspecies of the Gray or Long-tailed Shrew C. attenuata. The Gray Shrew occurs from the Himalayas southwards and eastwards through Thailand, Burma and China to Malaysia and Indonesia (Jenkins 1982, Corbet & Hill 1992). Corbet & Hill (1992) have since questioned the validity of the Christmas Island Shrew being considered conspecific with C. attenuata based on morphological characteristics.
Objects of the Act
Objects of the EPBC Act have been considered in developing this recovery plan, particularly:
a) to provide for the protection of the environment, especially those aspects of the environment that are matters of national environmental significance;
b) to promote ecologically sustainable development through the conservation and ecologically sustainable use of natural resources;
c) to promote the conservation of biodiversity; and
d) to promote a co-operative approach to the protection and management of the environment involving governments, the community, land-holders and indigenous peoples.
Objects e) to g) are not applicable due to absence of indigenous people and the species not being listed under international fauna agreements.
International Obligations
The Christmas Island Shrew is not listed under international fauna agreements.
Affected Interests
Public authorities, private companies and other organisations with affected interests:
Commonwealth Government, including:
- Dept of the Environment and Heritage DEH (including Parks Australia North, Natural Heritage Division, CI Rainforest Rehabilitation Program, Approvals and Legislation Division),
- Dept of Immigration, Multicultural and Indigenous Affairs (DIMIA)
- Dept of Transport and Regional Services (DOTARS),
Christmas Island National Park Advisory Committee,
Shire of Christmas Island,
CI Phosphates Pty Ltd (Phosphate Resources Ltd) (CIP),
Union of Christmas Island Workers,
Christmas Island Tourist Association,
Department of Environmental Protection,
Asia Pacific Space Centre,
Telstra Corporation Ltd,
Monash University, and
Australian zoos.
Role and interests of indigenous people
Not applicable. Christmas Island was first settled in 1888; prior to this time there were no indigenous peoples inhabiting the island (Commonwealth of Australia 2002).
Benefits to other species/ecological communities
Threats identified and management actions proposed for the Christmas Island Shrew are similar to those for other threatened endemic species that are restricted to rainforest vegetation communities on the island. Actions affording protection to plateau and terrace rainforest will also provide protection for other rainforest-dependent species (Table 1).
The targeted survey for the Christmas Island Shrew may provide additional information on the current distribution, status and habitat of the poorly known Christmas Island Gecko Lepidodactylus listeri and Christmas Island Blind Snake Ramphotyphlops exocoeti. During the course of targeted field surveys for the shrew, incidental records of these poorly known reptiles should be entered into an ‘Incidental Flora and Fauna Database’ to be established by Parks Australia North (PAN) on Christmas Island. The database should also include records of exotic species because of their potential threats as predators and competitors to native fauna.
Christmas Island Flying-fox Pteropus melanotus natalis*
DD3,*
Abbott’s Booby Papasula abbotti (listed Sula abbotti on EPBC Act)
E1, CE2
White-tailed Tropicbird (Christmas Island subspecies) Phaethon lepturus fulvus
CE2
Christmas Island Frigatebird Fregata andrewsi
V1
Christmas Island Goshawk Accipiter fasciatus natalis
E1, CE2
Christmas Island Imperial-Pigeon Ducula whartoni
CE2
Emerald Dove (Christmas Island subspecies) Chalcophaps indica natalis
CE2
Christmas Island Hawk-Owl Ninox natalis
V1, CE2
Glossy Swiftlet (Christmas Island subspecies) Collocalia esculenta natalis
CE2
Island Thrush (Christmas Island subspecies) Turdus poliocephalus erythropleurus
CE2
Christmas Island White-eye Zosterops natalis
CE2
Christmas Island Blind Snake Ramphotyphlops exocoeti
V1
Christmas Island Gecko Lepidodactylus listeri
V1
CE = Critically Endangered; E = Endangered; V = Vulnerable; DD = Data deficient; 1 = Listed under EPBC Act; 2 = ‘Action Plan for Australian Birds’ (Garnett & Crowley 2000); 3 = ‘Action Plan for Australian Bats’ (Duncan et al. 1999); and * = Recent evidence suggests the species has undergone significant declines in total population numbers and its status is in urgent need of review (CIP pers. comm.).
Social and economic impacts
Until it is determined whether the Christmas Island Shrew is extant, it is difficult to comment on the social and economic impacts resulting from management actions. The last confirmed records are from plateau and terrace rainforest, suggesting any development proposals and threatening processes affecting these habitats must include consideration of this species until further information is available. Similar to other endemic rainforest fauna that is threatened, the potential presence of the species could impact on economic activity or development. This arises from the listing under the EPBC Act, which invokes a range of protective provisions and offences where a population is to be affected. The magnitude of this potential impact is unknown, as it will vary with the location, size and extent of an affected population (once discovered), and the nature and extent of the activity, proposed or current.
Most fauna species on Christmas Island are endemic and some have the potential for attracting low impact ecotourism. The Christmas Island Shrew, although a cryptic component of the endemic fauna, provides an interesting ‘story’ as the only extant endemic mammal (excluding bats) on the island and the only Australian shrew. Such a ‘story’ may provide added appeal to tourists with a strong natural history background contemplating visiting the island. Rainforest rehabilitation, which provides employment for some islanders, may create potential habitat for the species in years to come.
Part B: Distribution and Location
Distribution
Current Known (or Likely) National Distribution: Endemic to Christmas Island (closely related species occur in Java and other parts of southeast Asia)
Historical Distribution: Widespread on Christmas Island at settlement, occurring in forest on both the plateau and adjacent to the shoreline and being described as ‘very abundant’ or ‘extremely common’ (Lister 1888, Andrews 1900).
Extent and Geographic Location(s) of Populations: Currently unknown, but, on the basis of available information (Figure 1), is considered extremely rare or possibly extinct on Christmas Island.
The Christmas Island Shrew was thought to be extinct until the accidental separate finding of two individuals in 1985:
One was found running from a bird’s nest fern that had recently fallen on to a track approximately 200m southwest of the shrine, in an area locally known as LB4 on the central plateau (approximate location: 10028’S, 105035’E) (J. Tranter, DEH, pers. comm.). This animal was kept in captivity for some twelve months.
The second was found on a walking track 30 to 40m north of the stream at No. 1 Dale (approx.: 10028’S, 105033’E) on the west coast in the late afternoon during fine weather (P. Goh, Dept of Foreign Affairs and Trade, pers. comm.). This individual died shortly afterwards while being held in captivity (J. Tranter, DEH, pers. comm.).
Information indicating the unconfirmed capture of two other shrews in 1958 when South Point (approx.: 10033’S, 105039’E) was being cleared for mining was provided by D. Powell (pers. comm. 1997 cited in Meek 1998).
Recently reported, unconfirmed sightings, following publicity regarding the species, were at:
the junction of the Pink House and Murray Roads (10029’S, 105038’E) (Coates, K. pers comm. 1996 cited in Meek 1998),
the Christmas Island Resort Pool (10027’S, 105042’E) (Rochford, M. pers. comm. 1997 cited in Meek 1998), and
Martin Point (10027’S, 105033’E) (Blackford, P. pers comm. 1997 cited in Meek 1998).
These sightings were investigated immediately by trained staff but are unlikely to have been Christmas Island shrew (P. Meek pers. comm.)
No confirmed sightings have been made since 1985, despite:
- Systematic surveys for the shrew during 1997-98 using a variety of techniques (Meek 2000).
- Recent surveys using a variety of techniques during environmental impact assessments on proposed developments (e.g. Asia Pacific Space Centre) (G. Richards, Greg Richards and Associates, pers. comm.).
- Earlier surveys (e.g. Tidemann 1988: 2036 trapnights with pitfall, Elliott and snapback traps in 1988; N. Dunlop: 1500 pitfall trapnights in 1985/1986; and H. Yorkston: 120 pitfall trap nights in 1987).
- Extensive nocturnal studies of the Christmas Island Hawk-Owl Ninox natalis (Hill & Lill 1998a, b), Christmas Island Pipistrelle Pipistrellus murrayi (Lumsden & Cherry 1997, Lumsden et al. 1999) and reptiles (Cogger & Sadlier 1981, 2001) throughout primary rainforest.
- Studies of gut contents and/or faecal material of potential predators, including the Feral Cat Felis catus (Tidemann et al. 1994, data in the CIP-commissioned 2002 fauna survey), Christmas Island Hawk-Owl (Hill & Lill 1998b) and the Wolf Snake Lycodon capucinus (Rumpff 1992, Cogger & Sadlier 2001).
Habitat
At the time of settlement, the Christmas Island Shrew was widespread in rainforest extending from the shoreline to the plateau (Lister 1888, Andrews 1900). It was not recorded whether the shrew occurred within other forest communities, for example scrubby forest in exposed situations on shallow soils, coastal fringe vegetation dominated by pandanus Pandanus christmatensis and the Cabbage Tree Scaevola taccada, and in perennially wet areas. The importance to the species of karst terrain (including caves, overhangs, rock crevices, sinkholes, and inland cliffs rising out of the terrace rainforest) is unknown.
The most recent records were of single individuals from tall plateau rainforest in deep soils (J. Tranter, DEH, pers. comm.) and terrace rainforest with shallow soils (P. Goh, DFAT, pers. comm.). The majority of primary plateau and terrace rainforest, including the locations for the two 1985 sightings, is now protected within the Christmas Island National Park. It is unknown whether the shrew may occur in secondary regrowth. There appear to have been no records from around human habitation on the island.
The Christmas Island Shrew was recorded to shelter in holes in rocks and roots of trees, and foraged predominantly on small beetles (Andrews 1900). Other Crocidura species either dig their own burrows in loose soil or leaf mould frequently under fallen trees and rocks or use those of other animals (Nowak 1999). An important component of habitat occupied by some Crocidura shrews is the presence of a high degree of ground cover with associated deep leaf litter and slightly moister soil (Dickman 1995). These preferences are linked to increased prey availability and predator avoidance, but may also facilitate burrow construction (Dickman 1988, 1995). It is not known whether the Christmas Island Shrew favours these microhabitats within the rainforest.
Habitat critical to the survival of the species
Until further information is obtained, by applying the precautionary principle to the EPBC Act criteria, all areas of primary plateau and terrace rainforest on the island should be considered as potential habitat critical to survival (Figure 1). If the shrew is found to be extant, identifying habitat requirements critical to survival is recommended.
Important populations
None known, as the species has not been recorded since 1985. Should any individuals be located, they would be regarded as constituting a component of an important population.