Biodiversity

Species Profile and Threats Database


For information to assist proponents in referral, environmental assessments and compliance issues, refer to the Policy Statements and Guidelines (where available), the Conservation Advice (where available) or the Listing Advice (where available).
 
In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.

EPBC Act Listing Status Listed as Endangered as Crocidura trichura
Recovery Plan Decision Recovery Plan required, this species had a recovery plan in force at the time the legislation provided for the Minister to decide whether or not to have a recovery plan (19/2/2007).
 
Adopted/Made Recovery Plans National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan] as Crocidura attenuata trichura.
 
Other EPBC Act Plans Threat Abatement Plan for Reduction in Impacts of Tramp Ants on Biodiversity in Australia and its Territories (Department of the Environment and Heritage (DEH), 2006p) [Threat Abatement Plan].
 
Threat Abatement Plan for Predation by Feral Cats (Environment Australia (EA), 1999b) [Threat Abatement Plan].
 
Policy Statements and Guidelines Survey guidelines for Australia's threatened mammals. EPBC Act survey guidelines 6.5 (Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC), 2011j) [Admin Guideline].
 
Information Sheets Final Report of the Christmas Island Expert Working Group to the Minister for the Environment Protection, Heritage and the Arts (Department of the Environment, Water, Heritage and the Arts (DEWHA), 2010a) [Information Sheet].
 
Federal Register of
    Legislative Instruments
Declaration under s178, s181, and s183 of the Environment Protection and Biodiversity Conservation Act 1999 - List of threatened species, List of threatened ecological communities and List of threatening processes (Commonwealth of Australia, 2000) [Legislative Instrument] as Crocidura attenuata trichura.
 
Amendment to the list of threatened species under section 178 of the Environment Protection and Biodiversity Conservation Act 1999 (156) (Commonwealth of Australia, 2013y) [Legislative Instrument] as Crocidura trichura.
 
Non-statutory Listing Status
IUCN: Listed as Critically Endangered (Global Status: IUCN Red List of Threatened Species: 2013.1 list)
Scientific name Crocidura trichura [86568]
Family Soricidae:Insectivora:Mammalia:Chordata:Animalia
Species author Dobson, 1889
Infraspecies author  
Reference http://www.iucnredlist.org/details/136379/0
Other names Crocidura tenuata trichura [26201]
Crocidura attenuata trichura [66638]
Distribution map Species Distribution Map

This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.

Illustrations Google Images

Originally described as a subspecies of Crocidura fuliginosa, the Christmas Island Shrew was later referred as C. attenuata (Jenkins 1976). This placement has been questioned and its relationships to Sumatran specimens and to mainland C. attenuata have also been doubted (Corbet & Hill 1992). Currently accepted as Crocidura attenuata trichura Dobson, 1888 (AFD 2010). DNA analysis of museum specimens indicate that all collections are from the same taxon and that the Christmas Island Shrew cytb is divergent at the species level (i.e. represents a separate species) (Eldridge et al. 2009). Now recognised as a distinct species, Crocidura trichura, rather than a subspecies of C. attenuata (AFD 2013).

The Christmas Island Shrew is a small mouse-like mammal with short legs (Meek 1997), with reddish-brown to dark slate grey colouring. It weighs between 4.5 and 6 g, and like other members of the Crocidura genus it has a distinctly pointed muzzle (Schulz 2004).

This subspecies is confined to Christmas Island (10°25'S, 105°40'E) in the Indian Ocean (Meek 2000).

Christmas Island is 135 km2 in size. The exact area of occupancy is unknown, however, the whole island has the potential for occupancy within areas of suitable habitat.

Crocidura attenuata is a widespread species, with numerous identified subspecies occurring in Nepal and China to peninsular Malaysia and Indonesia (Corbet & Hill 1992; Hutterer 1993).

A number of surveys on Christmas Island have failed to locate the Christmas Island Shrew. These include (Schulz 2004):

  • In 1997–1998 systematic surveys for the shrew were undertaken utilising a variety of techniques.
  • Environmental impact assessments on proposed developments (e.g. Asia Pacific Space Centre) failed to identify the species.
  • Pitfall trapping and Elliot trapping in surveys from 1985–1988 for various island study projects did not locate the species.
  • Primary rainforest surveys, mostly nocturnal, for other listed Christmas Island fauna, such as the Christmas Island Hawk-Owl (Ninox natalis), Christmas Island Pipistrelle (Pipistrellus murrayi) and reptiles also failed to locate the Christmas Island Shrew.
  • Studies of gut contents and/or faecal material of potential predators, including the Feral Cat (Felis catus), Christmas Island Hawk-Owl and the Wolf Snake (Lycodon capucinus) also did not identify the species.

The Christmas Island Shrew was considered widespread and abundant on Christmas Island when first recorded (Andrews 1900). By 1908, the Christmas Island Shrew was thought to be extinct along with two endemic rats of Christmas Island, Rattus nativitatis and Maclear's Rat (Rattus macleari) (Andrews 1909). In 1985 two individuals were captured, both on the western side of the island and both of which died in captivity. A further four anecdotal sightings of the species have occurred, but efforts to trap more specimens have been unsuccessful (Meek 1997, 2000; Tidemann 1989), though Crocidura shrews are noted to be extremely difficult animals to capture (P. Vogel, pers comm., cited in Meek 1997).

General Habitat

The preferred habitat of the Christmas Island Shrew is unknown. The 1985 records of the species occurred in tall plateau rainforest in deep soils (J. Tranter, pers. comm., cited in Schulz 2004) and terrace rainforest with shallow soils (P. Goh, pers. comm., cited in Schulz 2004). The majority of primary plateau and terrace rainforest, including the locations for these two sightings, is now protected within the Christmas Island National Park. It is unknown whether the shrew may occur in secondary rainforest regrowth (Schulz 2004). Four 1997 anecdotal observations of the species occurred in coastal terrace habitat (Meek 1997, 2000). No records from human settlement areas have been made on the island (Schulz 2004).

Sheltering Habitat

Andrews (1900) noted the species as likely to use holes in rocks and the roots of trees as sheltering habitat. 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, cited in Schulz 2004). Many other Crocidura shrews require a high degree of ground cover and deep leaf litter in habitat, often with slightly moister soils for easier burrow construction and to assist in foraging and with predator avoidance (Dickman 1995). It is not known whether the Christmas Island Shrew favours these microhabitats within the rainforest.

Nothing is recorded on the microhabitat, conditions or other aspects of breeding in this subspecies. Its breeding biology is likely to be similar to other Crocidura shrews from tropical climates that reach sexual maturity very early, with some maturing within a couple of months of weaning to become reproductively active in the same year that they are born (Churchfield 1990). Breeding can be continuous but is usually interrupted by the dry season (Medway 1978). Gestation in Crocidurine shrews averages 30 days. Nests are constructed by females and sometimes males, a few days before birth. Young are born naked and blind and Crocidurine shrews usually have litter sizes of less than five that are weaned at around 22–25 days (Churchfield 1990; Meek 1997, 2000).

Crocidurine shrews are insectivorous. Sight is poor in most shrews and there is a dependence on olfactory, auditory and tactile senses when foraging. There is evidence of echolocation in Sorex (Buchler 1976) and Blarina (Tomasi 1979) species, although it is not believed to be an important foraging tool. Hunting mostly involves searching using the sensitive snout to probe the litter layer and low plant substrate until prey is located. Some shrews are also known to cache prey when there is an abundance of food (Meek 1997, 2000).

Disease

Disease is considered to be the most likely cause of the decline of the Christmas Island Shrew, as the species was considered probably extinct by 1908 before major broadscale habitat destruction was undertaken. During 1901 to 1904, the endemic Maclear's Rat became extinct on Christmas Island, most likely as the result of the introduction of the pathogen trypanosome via infected Black Rats (Rattus rattus) (Pickering and Norris 1996, cited in Schulz 2004).

Yellow Crazy Ant (Anoplolepis gracilipes)

An invasive species, accidentally introduced to the island between 1915 and 1934, Yellow Crazy Ants form multi-queened supercolonies. On Christmas Island dramatic increases in supercolony formation was noted in the mid to late 1990s. Aerial baiting of the island began in September 2002, however supercolonies were estimated to have already infested over 2500 ha of rainforest. Impacts from the Yellow Crazy Ant noted include a reduction of approximately 30% in the population of the Red Crab (Gecaroidea natalis) due to ant attack; dramatically altered plant community dynamics; damage to trees resulting in dieback; and canopy thinning due to the ants' ecology of farming scale insects. The direct effects on the shrew are unknown, but it is likely that breeding, shelter and foraging sites would be severely affected. It is also likely the ants kill young animals in the nest, and possibly adults in severely affected areas (Schulz 2004).

Habitat Loss

Approximately 33% of Christmas Island's rainforest has been destroyed for phosphate mining (Schulz 2004). In total, the island's vegetation has reduced by 25% due to clearing (DEWHA 2010a). Whilst the Christmas Island Shrew was noted to be in dramatically low numbers prior to mining on the island, loss of habitat would not assist in recovery of the species. Two unconfirmed reports of the species were recorded in 1958 in habitat being cleared by bulldozers for mining. Habitat modification due to mining has detrimentally affected foraging resources, predation risk and microhabitat requirements, for example, via the loss of groundwater and moisture levels (Schulz 2004, Meek 1997, 2000).

New proposals to clear primary rainforest on vacant crown land may apply additional pressure on any remaining shrew populations. These proposals include phosphate mining at sites in the eastern section of the island, and activities associated with developments such as the siting of a mobile phone tower on Limestone Hill, South Point; the Christmas Island airport upgrade; road re-alignment and new port facilities north of the former Christmas Island Resort area (Schulz 2004).

Habitat Alteration

The loss of other endemic species from Christmas Island such as Rattus nativitatis and Maclear's Rat, and impacts on the populations of species, such as the Red Crab, may alter the structure of rainforest habitat also through adverse changes in microhabitats. This may affect rainforest critical to the maintenance of shrew populations (Schulz 2004, Meek 1997, 2000).

Predation

No instances of predation have been recorded. However, it is likely that introduced predators (e.g. Feral Cat, Black Rat and Wolf Snake), the naturalised Nankeen Kestrel (Falco Cenchroides), and endemic predators, such as the Christmas Island Goshawk (Accipiter hiogaster natalis) and Christmas Island Hawk-Owl may opportunistically predate on the Christmas Island Shrew (Meek 1997, 2000).

Small Population Size

Once recorded as abundant, the shrew is now considered rare, and likely only in low densities. Small population size increases the risk of extinction through inbreeding depression and stochastic events (Caughley & Sinclair, cited in Schulz 2004). The network of wide mining haulage roads may have further isolated populations due to a possible reluctance of individuals to cross wide open spaces due to elevated predation risk (Schulz 2004, Meek 1997, 2000).

Other Potential Threats

Roadkills, fire, and domestic cats and dogs on the island may also pose additional risks to the species (Schulz 2004).

A Recovery Plan for the Christmas Island Shrew (Schulz 2004) has been adopted and identifies the following recovery objectives:

  • clarify the taxonomic status of the Christmas Island Shrew
  • clarify the current status and distribution
  • maximise the opportunity for the viability of this species in the wild.

Habitat protection from, and control or eradication of, the Yellow Crazy Ant is also identified as important to recover the species. The Department of the Environment, Water, Heritage and the Arts has adopted a threat abatement plan for the control of tramp ants, invasive ant species from around the world, to assist land managers and recovery programs where these species are identified as a threat (DEH 2006p). Parks Australia North (PAN) has, as a priority conservation management objective for the island, the control of the crazy ant supercolonies, under which the 2002 aerial baiting was undertaken. This was considered successful in controlling the invasive species in 2500 ha of rainforest. Crazy ants are still present in low densities and PAN staff will continue to monitor any new supercolony formation and treat by hand baiting. The impact of this on the shrew, both through contact with baits and flow on impacts on prey species, is unknown (Schulz 2004).

Management documents for the Christmas Island Shrew include:

  • Christmas Island Shrew Recovery Plan (Crocidura attenuata trichura) 1997-2002 (Meek 1997).
  • National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz 2004).
  • Threat Abatement Plan for Reduction in Impacts of Tramp Ants on Biodiversity in Australia and its Territories (DEH 2006p).
  • Threat Abatement Plan for Predation by Feral Cats (EA 1999b).

The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.

Threat Class Threatening Species References
Ecosystem/Community Stresses:Ecosystem Conversion:Alteration of habitat characteristics National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Ecosystem/Community Stresses:Indirect Ecosystem Effects:Loss and/or fragmentation of habitat and/or subpopulations National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Energy Production and Mining:Mining and Quarrying:Habitat destruction, disturbance and/or modification due to mining activities National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Human Intrusions and Disturbance:Human Intrusions and Disturbance:Human induced disturbance due to unspecified activities National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Human Intrusions and Disturbance:Human Intrusions and Disturbance:Mechanical disturbance during construction, maintanance or recreational activities National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation Felis catus (Cat, House Cat, Domestic Cat) Christmas Island Shrew Recovery Plan (Crocidura attenuata trichura) 1997-2002 (Meek, P.D., 1997) [Recovery Plan].
National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation Rattus rattus (Black Rat, Ship Rat) Christmas Island Shrew Recovery Plan (Crocidura attenuata trichura) 1997-2002 (Meek, P.D., 1997) [Recovery Plan].
New evidence concerning the extinction of the endemic murid Rattusmacleari Thomas 1887, from Christmas Island, Indian Ocean. Australian Mammalogy. 19:19-25. (Pickering, J & Norris, C.A., 1996) [Journal].
National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation Anoplolepis gracilipes (Yellow Crazy Ant, Gramang Ant, Long-legged Ant, Maldive Ant) National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation Canis lupus familiaris (Domestic Dog) Christmas Island Shrew Recovery Plan (Crocidura attenuata trichura) 1997-2002 (Meek, P.D., 1997) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or predation by birds National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition, predation and/or habitat degradation Lycodon aulicus (Wolf Snake, Common Wolf Snake, Asian Wolf Snake) National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Introduction of pathogens and resultant disease National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Problematic Native Species:Competition and/or predation Gecarcoidea natalis (Christmas Island Red Crab) Christmas Island Shrew Recovery Plan (Crocidura attenuata trichura) 1997-2002 (Meek, P.D., 1997) [Recovery Plan].
Invasive and Other Problematic Species and Genes:Problematic Native Species:Competition and/or predation by birds National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Natural System Modifications:Fire and Fire Suppression:Inappropriate and/or changed fire regimes (frequency, timing, intensity) National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Residential and Commercial Development:Housing and Urban Areas:Habitat loss, modification and fragmentation due to urban development National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Species Stresses:Indirect Species Effects:Low numbers of individuals National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].
Transportation and Service Corridors:Roads and Railroads:Vehicle related mortality National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura) (Schulz, M., 2004) [Recovery Plan].

Andrews, C.W. (1900). A monograph of Christmas Island (Indian Ocean). London: British Museum (Natural History).

Andrews, C.W. (1909). On the fauna of Christmas Island. Proceedings of the Zoological Society of London. 1909:101-103.

Australian Faunal Directory (2010). Subspecies Crocidura attentuata trichura Dobson, 1888. [Online]. Department of the Environment, Water, Heritage and the Arts, Canberra. Available from: http://www.environment.gov.au/biodiversity/abrs/online-resources/fauna/afd/taxa/Crocidura_attenuata_trichura. [Accessed: 28-May-2010].

Buchler, E.R. (1976). The use of echolocation by the wandering shrew Sorex vagrans. Animal Behaviour. 24:858-873.

Churchfield, S. (1990). The Natural History of Shrews. New York: Comstock Publishing Associates.

Corbet, G.B. & J.E, Hill (1992). The Mammals of the Indomalayan Region: A Systematic Review. Oxford: Oxford University Press.

Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC) (2011j). Survey guidelines for Australia's threatened mammals. EPBC Act survey guidelines 6.5. [Online]. EPBC Act policy statement: Canberra, ACT: DSEWPAC. Available from: http://www.environment.gov.au/epbc/publications/threatened-mammals.html.

Department of the Environment and Heritage (DEH) (2006p). Threat Abatement Plan for Reduction in Impacts of Tramp Ants on Biodiversity in Australia and its Territories. [Online]. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/tap/trampants.html.

Department of the Environment, Water, Heritage and the Arts (DEWHA) (2010a). Final Report of the Christmas Island Expert Working Group to the Minister for the Environment Protection, Heritage and the Arts. [Online]. Canberra: DEWHA. Available from: http://www.environment.gov.au/parks/publications/christmas/final-report.html.

Dickman, C. (1995). Diets and habitat preferences of three species of Crocidurine shrews in arid southern Africa. Journal of Zoology, London. 237:499-513.

Eldridge, M.D.B., R.N. Johnson & P.D. Meek (2009). Molecular Systematics of the Extinct? Christmas Island Shrew Crocidura attenuata trichura. In: Semi-Centenary and 55th Meeting in Perth July 5-9, 2009 Scientific Program.

Environment Australia (EA) (1999b). Threat Abatement Plan for Predation by Feral Cats. [Online]. Biodiversity Group, Environment Australia. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/tap/cats08.html.

Hutterer, R. (1993). Order Insectivora. In: Wilson, D.E. & D.M, Reeder, eds. Mammals of the World: A taxonomicand geographic reference. 2nd edition. Page(s) 69-130. Washington: Smithsonian Institution.

International Union for Conservation of Nature (IUCN) (2010). IUCN Red List of Threatened Species. Version 2010.4. [Online]. Available from: http://www.iucnredlist.org.

Medway, Lord (1978). The Wild Mammals of Malaya (Peninsula Malaysia) and Singapore. Kuala Lumpur: Oxford University Press.

Meek, P.D. (1997). Christmas Island Shrew Recovery Plan (Crocidura attenuata trichura) 1997-2002. Environment Australia.

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.

Schulz, M. (2004). National Recovery Plan for the Christmas Island Shrew (Crocidura attenuata trichura). [Online]. Department of the Environment and Heritage. Canberra: Commonwealth of Australia. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/recovery/c-attenuata-trichura/index.html.

Tidemann, C.R. (1989). Survey of the Christmas Island Shrew and other terrestrial mammals. Report to ANPWS, Australian National University.

Tomasi, T.E. 60 (1979). Echolocation by the short-tailed shrew Blarina brevicauda. Journal Mammalogy. 60:751-759.

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This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.

Citation: Department of the Environment (2014). Crocidura trichura in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Mon, 14 Jul 2014 14:21:58 +1000.