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Pipistrellus murrayi

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA MAMMALIA CHIROPTERA VESPERTILIONIDAE

Scientific Name: Pipistrellus murrayi
Species Authority: Andrews, 1900
Common Name(s):
English Christmas Island Pipistrelle
Synonym(s):
Pipistrellus tenuis Andrews, 1900 subspecies murrayi
Taxonomic Notes: Although there are differing opinions regarding the taxonomic status of the Christmas Island population, Koopman (1973, 1993) suggested P. murrayi was conspecific with P. tenuis without presentation of any data. Kitchener et al. (1986) considered P. murrayi distinct, though with little information given, but more information was given in a letter to Chris Tidemann. Hill and Harrison (1987) listed P. murrayi as a separate species in a revision of all Vespertilioninae based on baculum. We follow the IUCN SSC Chiroptera Specialist Group (P. Racey pers. comm. 2008) and Tidemann and Lumsden (2008) in recognizing P. murrayi as distinct from P. tenuis pending additional studies into the systematic status of these taxa.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered A2abce; B1ab(iv,v)+2ab(iv,v); C1+2a(i,ii); D ver 3.1
Year Published: 2010
Date Assessed: 2009-10-04
Assessor(s): Lumsden, L., Racey, P.A. & Hutson, A.M.
Reviewer(s): Cox, N. (Global Mammal Assessment Team), Racey, P.A. & Hutson, A.M. (Chiroptera Red List Authority)
Justification:

This species is listed as Critically Endangered and tagged as possibly extinct. There has been extensive survey work for, and monitoring of, this species in recent years documenting a dramatic population decline in excess of 90% in three generations based on an index of relative abundance from bat detectors (and subsequently by direct observation of the remaining individuals at a single roost). As recently as January 2009, there were thought to be as few as 20 remaining individuals. By August 2009, there appears to have been only one remaining individual, which was consistently recorded in its foraging and roosting areas. This individual went missing on 27 August 2009 and no individuals have since been located. There are serious concerns that Pipistrellus murrayi is now extinct; however, because the last known record for the species was recent there is still a possibility of its continued existence. Should there be any remaining individuals, these are almost certain to occupy a single location.

History:
2008 Critically Endangered (IUCN 2008)
2008 Critically Endangered

Geographic Range [top]

Range Description: This species is endemic to Christmas Island (Australia), approximately 135 km² in area, located in the eastern Indian Ocean. Although the bat was once widespread on the island, the last known individuals were recorded only in the western portion with no records from the rest of the island for a number of years.
Countries:
Possibly extinct:
Christmas Island
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population:

Because P. murrayi is (or was) the only microbat on Christmas Island, ultrasonic bat detectors are an effective technique for documenting its status, as it is obvious if the species is present or not, since it is readily recorded and can not be confused with, or obscured by, other species. Intensive detector sampling over the last decade (almost continuous since 2004) has provided unusually detailed documentation of its decline, resulting in it being one of the most intensely monitored bat species on the planet.  

This species was widespread and common until the mid 1980s (Tidemann 1985). By 1994 its range had contracted away from the north-east section (which is where the only town is located), and it had a patchy distribution and declining abundance (Lumsden and Cherry 1997). Between 1994 and 1998 there was a further westward range contraction and an apparent mean reduction of 33% in relative abundance, although this was not statistically significant (Lumsden et al. 1999; Schulz and Lumsden 2004). Between 1998 and 2004 there was a decline of between 55 and 65% in relative abundance and a continued westward contraction of range in the order of 25 to 50% (James 2005). This decline has continued and the species was considered to be confined to the far west of the island, no longer occurring across more than 90% of its former range (James and Retallick 2007; Lumsden et al. 2007). Long-term monitoring using bat detectors indicates this species underwent a 90% decline in abundance between 1994 and 2006 (James and Retallick 2007, Lumsden et al. 2007). Since 2006 this decline continued at an alarming rate with the species disappearing from many of the few remaining sites where it was present in 2006 (Parks Australia North Christmas Island unpublished data)

In December 2008, P. murrayi was thought to be restricted to a single foraging area and a single roost site (Lumsden and Schulz 2009). Although the roost site had previously contained as many as 50 individuals, by January 2009 there were only four adults present. The behaviour of these individuals suggested that they were lactating females with four dependent young in the roost. The total population was then estimated to be less than 20 individuals in order to account for the possibility of small undetected colonies (Lumsden and Schulz 2009). Lumsden and Schulz (2009) stated that the January findings indicated that

"without urgent intervention there is an extremely high risk that this species will go extinct in the near future. While it can not be precisely predicted when this would occur if there was no intervention, it is highly likely that it will be within the next 6 months, i.e. by June 2009" (pg. 7).

Unfortunately, this predicted decline of the species appears to have been prescient. After the January findings, Dr. Lumsden urgently sought approval to capture the remaining individuals for a captive breeding program, the details of which had been outlined in a feasibility report (Lumsden and Schulz 2009). Rather than acting immediately the Australian government established an Expert Working Group, and waited for its report in July 2009 (Beeton et al. 2009) before approving this intervention. In August 2009 a team led by Lumsden of eight bat experts and captive breeding specialists from Zoos Victoria attempted to take the remaining individuals into captivity. During the four weeks of intensive sampling, which used 30 bat detectors, only one individual could be found, and it evaded all attempts to catch it. On 27 August this individual also disappeared, and all survey work since that night has failed to detect the species. While it is possible that this individual moved to a new area, shifting both its roosting and foraging areas on the same night, this is considered unlikely as both areas had been continually used for at least the last ten years by members of this colony (L. Lumsden pers. comm.). It is quite possible that this is one of the few times that an extinction of species in the wild can be marked to the day.

Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species roosts under bark, in dead foliage, and in tree hollows. Maternity roosts were discovered in late 2005 under shedding bark of dead forest trees (Tristiropsis acutangula and Inocarpus fagifer) and in a hole in a palm (Arenga listeri), many of which were heavily decayed and collapsed soon after (Lumsden et al. 2007). Females form colonies of up to approximately 50 individuals, while males often roost solitarily (Lumsden et al. 1999, 2007). Generation length of this species is likely to be 4-5 years (L. Lumsden, D.J. James pers. comm.). This species roosts in mature, tropical, evergreen, closed canopy rainforests and mature, tropical, semi-deciduous rainforests (Lumsden et al. 1999; James and Retallick 2007; Lumsden et al. 2007). It feeds in and over these forests and also along tracks, and in and over secondary forests and thickets of woody weeds (Lumsden et al. 1999, James and Retallick 2007, Lumsden et al. 2007). It feeds on a range of small flying invertebrates, predominantly moths, beetles, and flying ants (Lumsden and Schulz 2009).
Systems: Terrestrial

Threats [top]

Major Threat(s): The reasons for the decline of this species remain unclear. While habitat loss may have caused some declines in the past, 75% of the island is covered by primary or secondary rainforest, with little change to the habitat over the last 20 years. The major threats to the species may include predation or disturbance to bats within their roosts from introduced species, e.g. Common Wolf Snake Lycodon aulicus capucinus, Feral Cat Felis catus, Black Rat Rattus rattus and Giant Centipede Scolapendra morsitans (Lumsden et al. 2007). Although not considered the primary cause of decline, the recent explosion of Yellow Crazy Ants Anoplolepis gracilipes is likely to have exacerbated the situation. It is also possible that some form of disease may be contributing to the decline, however, individuals appear in good health, with the exception of low white blood cell counts although the significance of these findings is unclear (Lumsden et al. 2007). Even the last known individual appeared to behave normally and looked healthy before it vanished (L. Lumsden pers. comm.).

Conservation Actions [top]

Conservation Actions:

There are serious concerns that P. murrayi is now extinct. Despite the extensive coverage of detector surveys in recent years, there is still a slight possibility that a small colony remains undetected. Should a small population be discovered, these individuals should be captured immediately in order to start a captive breeding program. Such a program has been shown to be the best approach for the recovery of the species once it reached critically low levels and with the cause of the decline unknown (Lumsden and Schulz 2009)

This species is listed as Critically Endangered under Australia's Environmental Protection and Biodiversity Conservation Act. The last known population of the species roosted within a protected area, Christmas IslandNational Park and foraged just outside the park in leasehold land. A range of management actions from the Recovery Plan (Schulz and Lumsden 2004) had been implemented, including installing protective barriers around the base of the few known remaining roost trees, and establishing bat boxes in an attempt to provide additional roost sites. Christmas IslandNational Park staff are continuing the detector surveys in the hope of finding any remaining individuals. It has been recommended that this work continue for six months after the last record of the species (Beeton et al. 2009)


Citation: Lumsden, L., Racey, P.A. & Hutson, A.M. 2010. Pipistrellus murrayi. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 01 October 2014.
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