Prepared by Martin Schulz for
The Department of the Environment and Heritage, 2004
ISBN 0 642 55011 5
Part B: Distribution and location
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: 10°28'S, 105°35'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.: 10°28'S, 105°33'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.: 10°33'S, 105°39'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 (10°29'S, 105°38'E) (Coates, K. pers comm. 1996 cited in Meek 1998),
- the Christmas Island Resort Pool (10°27'S, 105°42'E) (Rochford, M. pers. comm. 1997 cited in Meek 1998), and
- Martin Point (10°27'S, 105°33'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 trap nights with pitfall, Elliott and snapback traps in 1988; N. Dunlop: 1500 pitfall trap nights 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).
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 bypandanus 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.
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.
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.