The Action Plan for Australian Bats
Environment Australia, 1999
ISBN 0 642 2546 363
Recovery outlines and taxon summaries (continued)
Recovery outline: Christmas Island Pipistrelle
Family:Vespertilionidae
Scientific name: Pipistrellus murrayi Andrews, 1900
Common name: Christmas Island Pipistrelle
Conservation status: Endangered (C1)
Intraspecific taxa
Probably none; considered to be an endemic species by Kitchener et al. (1986) and Hill and Harrison (1987), but listed as conspecific with P. tenuis by Wilson and Reeder (1993). Given the small size of the species (3g), consequent low mobility and the distance to the nearest source population of P. tenuis, commonsense indicates that this should be treated as an isolated taxon.
Former distribution
Only known from Christmas Island, Indian Ocean.
Current distribution
Christmas Island, Indian Ocean.
Habitat
Occurs in the range of habitats found on the island: primary rainforest on both the plateau and terraces, secondary regrowth, old mining fields, and areas which have been rehabilitated. In 1984, animals were recorded foraging in many areas, particularly along the numerous tracks cleared through the forest and along forest edges over seral vegetation (Tidemann 1985). Nearly all of these tracks were blocked by tree-falls during a cyclone in 1988 (Tidemann 1989) and in studies in 1994 and 1998 most foraging was observed in small clearings in primary and secondary rainforest (Lumsden and Cherry 1997, Lumsden et al. 1999). While old mined areas and recently rehabilitated areas may be used for foraging, there are no roosting opportunities in these areas. A limited number of non-breeding roosts have been located: all were in primary forest, in hollows in large live trees, under exfoliating bark on dead trees, and under dead pandanus and palm fronds (Lumsden et al. 1999). There is currently no information on the location of maternity roosts.
Reasons for decline
Approximately 25% of the island has been cleared of primary rainforest for phosphate mining. Although some of these areas now provide foraging habitat there are no roosting opportunities, and hence the area providing roosts has decreased since settlement late last century.
More recently, there has been a marked decline in numbers between studies conducted in 1984 (Tidemann 1985), 1994 (Lumsden and Cherry 1997) and 1998 (Lumsden et al. 1999). The distribution of this species has contracted westwards with most records now in the western section of the island. In 1984 it was located throughout the island. Despite extensive sampling of suitable habitat, it now appears to be no longer present in the north-eastern section of the island (Lumsden et al. 1999). Comparison of results from 22 sites sampled using Anabat detectors in both 1994 and 1998, showed a decline in abundance of bat activity of 33% within the last four years (Lumsden et al. 1999). Although this difference was not significant due to the high level of variability, it does, however, suggest that the decline is continuing, possibly at a rapid rate.
The reasons for the decline are currently unknown. Clearing of primary rainforest ceased in 1988, and hence roosting habitat is unlikely to have changed. Foraging habitat has, however, changed markedly with the regrowth of the extensive network of bulldozed drill lines that were constructed in the 1960s. There are a number of potential predators of P. murrayi, including the Wolf Snake (Lycodon aulicus capucinus) which was accidentally introduced to the island in 1987 (Smith 1988, Fritts 1993), and is currently expanding out from the settlement area into the centre of the island. The distribution of this species largely mirrors that of P. murrayi occurring through the north-east section where P. murrayi has recently disappeared. In the centre of the island where the two species overlap P. murrayi is currently in decline. Another potentially serious threat to the species is the introduced ant Anoplolepis gracilipes (Lumsden et al. 1999). There has been a dramatic increase in population densities of this species in recent years, with the formation of supercolonies containing millions of individuals. These ants are currently having a catastrophic impact on the red crab populations on the island, killing thousands of individuals. The impact of these ants on P. murrayi is not yet known, however, individuals are vulnerable to ant attack, as evidenced by the death of an individual in a harp trap covered in ants. Large numbers of ants have been observed in the typical roost sites used by this species, which may result either in death or desertion of roosts. Other potential predators of P. murrayi include Nankeen kestrels, black rats and feral cats (Lumsden et al. 1999).
Conservation reserves on which species occurs
Christmas Island National Park.
Other public land on which species occurs
Christmas Island, outside the park.
Other land on which species occurs
None.
Is knowledge about species adequate for objectives and actions to be defined accurately?
Partially. Knowledge is sufficient to set research objectives, however, lack of information on the causes of recent declines prevents the development of recovery management actions at this stage.
Recovery objectives
- Determine the causes of recent declines and formulate appropriate management actions.
- Undertake management actions to prevent further decline and to re-establish population numbers to former levels.
- Establish a long-term monitoring program to monitor the recovery.
Management and research actions completed or underway
- Gazettal of the Christmas Island National Park and preparation of management plan.
- A study of the status, habitat requirements and management was conducted in 1984 (Tidemann 1985).
- A brief follow-up study was conducted in 1994 (Lumsden and Cherry 1997).
- A study investigating the conservation status, distribution and abundance and habitat requirements for foraging and roosting was funded by Environment Australia in 1998 (Lumsden et al. 1999).
Management and research actions required
Research actions required:
- Determine roosting requirements, in particular maternity roosts, and locate and describe roosts in areas of low bat activity, especially at the current edge of the distribution. Investigate potential threatening processes affecting maternity roosts and dependent young which could account for the decline in the species.
- Determine whether the distribution and abundance are uniform throughout the year, or if different patterns emerge during the breeding season.
- Investigate the impact of the Wolf Snake on P. murrayi, in particular in relation to predation of roosting bats.
- Investigate the impact of the introduced ant Anoplolepis gracilipes on P. murrayi, particularly in relation to roosting bats.
- Investigate the impact of the other potential predators: the black rat, feral cat and Nankeen kestrel.
- Establish a long-term monitoring program. This should comprise two components: standardised driving detection technique to investigate changes in distribution (to be undertaken at 3-monthly intervals by Parks Australia North staff on Christmas Island), and a more extensive re-sampling of sites surveyed in the 1998 study, at 2 to 5 year intervals, to monitor changes in both distribution and abundance.
- Studies of this species should be linked to a re-assessment of the Christmas Island Flying-fox, Pteropus melanotus natalis, of which no appraisal has been made since 1984.
Management actions required:
- Actions will largely depend on the results of research aimed at determining the cause of the decline.
- Key areas have been identified in the western section of the island for this species (Lumsden et al. 1999), and management actions should focus on these areas.
Organisation(s) responsible for conservation of species
Environment Australia.
Other organisation(s)/individuals involved
Christmas Island Council, Territories Office, Christmas Island Phosphate.
Can recovery be carried out with existing resources?
No.
Research Actions:
- Ecological studies and identification of threats: $160,000
- Monitoring program: $30,000
- $190,000
Management Actions:
- Currently unknown.
(Ecological studies based on: 2 people for 9 months 82K, 1 person extra 3 months for write-up, expenses 27K, vehicle 10K, airfares and freight 16K, equipment 10K; monitoring program: regular PAN monitoring 2K/year x 5 years, re-sampling sites 20K).
Bibliography
Andrews C.W. 1900. A Monograph of Christmas Island (Indian Ocean). British Museum of Natural History, London.
Fritts T.H. 1993. The common wolf snake, Lycodon aulicus capucinus, a recent colonist of Christmas Island in the Indian Ocean. Wildlife Research 20, 261–6.
Hill J.E. and D. L. Harrison 1987. The baculum in the Vespertilioninae (Chiroptera: Vespertilionidae) with a systematic review, a synopsis of Pipistrellus and Eptesicus, and the descriptions of a new genus and subgenus. Bulletin of the British Museum (Natural History) Zoology 52, 225–305.
Kitchener D. J., Caputi N. and Jones B. 1986. Revision of Australo-Papuan Pipistrellus and Falsistrellus (Microchiroptera: Vespertilionidae). Records of the West Australian Museum 12, 435–495.
Lumsden L. and 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. and Schulz, M. 1999. Population dynamics and ecology of the Christmas Island Pipistrelle, Pipistrellus murrayi, on Christmas Island. Final Report. Consultancy for Parks Australia North – Christmas Island. Arthur Rylah Institute for Environmental Research, Heidelberg, Victoria.
Smith L.A. 1988. Lycodon aulicus capucinus, a colubrid snake introduced to Christmas Island, Indian Ocean. Records of the Western Australian Museum 14, 251–2.
Tidemann C. 1985. A study of the status, habitat requirements and management of the two species of bat on Christmas Island (Indian Ocean). Report to the Australian National Parks and Wildlife Service, Canberra.
Tidemann C.R. 1989. Survey of the terrestrial mammals on Christmas Island (Indian Ocean). Report to the Australian National Parks and Wildlife Service, Canberra.
Wilson D.E. and Reeder, D.M. eds. 1993. Mammal Species of the World: a Taxonomic and Geographic Reference. Second Edition. Smithsonian Institution Press, Washington.
Authors for the species
Lindy Lumsden
Chris Tidemann