|Scientific Name:||Pipistrellus murrayi Andrews, 1900|
Pipistrellus tenuis ssp. murrayi Andrews, 1900
|Taxonomic Notes:||This taxon has in the past sometimes been included as a subspecies of Pipistrellus tenuis (Koopman 1973, 1993), but its status has been confirmed by genetic and morphological assessment, which revealed it was a full species endemic to Christmas Island (Helgen et al. 2009).|
|Red List Category & Criteria:||Extinct ver 3.1|
|Assessor(s):||Lumsden, L., Racey, P.A. & Hutson, A.M.|
This species is listed as Extinct. There has been extensive survey work for, and monitoring of, this species over recent decades which has documented a dramatic population decline from previously being common and widespread across Christmas Island. It was listed as Critically Endangered in 2006 after a decline in excess of 90% in three generations (12–15 years) based on an index of relative abundance from bat detectors, and subsequently by direct observation of the remaining individuals at a single roost. In January 2009, the total known adult population was four individuals and the estimated population was considered to be fewer than 20 individuals. By August 2009, only one remaining individual was found during an extensive survey, which was recorded consistently each day in its foraging and roosting areas. This individual disappeared on 27 August 2009 and no individuals have been located since, despite extensive searching using proven techniques.
|Previously published Red List assessments:|
|Range Description:||This species was endemic to Christmas Island (approximately 135 km² in area), Australia, which is in the eastern Indian Ocean. Although this bat was once widespread on the island, the last known individuals were recorded in the far western section of the island with no records from the rest of the island for a number of years.|
Regionally extinct:Christmas Island
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Because Pipistrellus murrayi was the only echolocating bat on Christmas Island, ultrasonic bat detectors were an effective technique for documenting its status, as it was readily recorded and could not be confused with, or obscured by, other species. Intensive detector sampling over many years (intermittent between the mid-1990s and 2004, and then almost continuous until and after its extinction) has provided an unusually detailed documentation of its decline, resulting in it being one of the most intensely monitored bat species on the planet.|
Although there were no reliable population estimates, P. murrayi was reported to be abundant and widespread across Christmas Island at the time of its first settlement (1890s) (Andrews 1900), and was still abundant and widespread at the time of the first substantial study of it in 1984 (Tidemann 1985). By 1994 its range had contracted away from the north-east section of the island (which is where the only town is located), its distribution had become patchy, and it had started to decline in 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 continuing westward contraction of range of about 25 to 50% (James 2005). This decline continued and the species was then (ca 2007) 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 indicated this species underwent a 90% decline in abundance between 1994 and 2006 (James and Retallick 2007, Lumsden et al. 2007). This decline continued at a severe and consistent rate with the species disappearing from many of the few remaining sites where it was present in 2006 (Parks Australia North Christmas Island unpub. data).
In December 2008, the remaining P. murrayi population was thought to be restricted to a single foraging area and a single roost area (Lumsden and Schulz 2009). Although the remaining single known 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 fewer 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 was an extremely high risk that the species would become extinct in the near future. While it could not be precisely predicted when this would occur if there was no intervention, it was predicted that this could occur within the following six months.
Unfortunately, this predicted extinction of the species was realised. After the January findings, approval was urgently sought 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 of bat experts and captive breeding specialists attempted to take the remaining individuals into captivity. During the four weeks of intensive sampling, which employed 30 bat detectors each night to document the location of the remaining individuals, only one individual could be found, and despite extensive trapping efforts using standard and innovative techniques, it evaded all attempts to catch it (Lumsden 2009). On 27 August 2009 this individual also disappeared, and all survey and trapping attempts since that night have failed to detect the species. This is one of the few times that an extinction of a species in the wild can be marked to the day. The failure of the responsible agencies and managers to act quickly in response to the evidence of the rapid population decline is considered to have contributed to the extinction of this species (Lunney et al. 2011, Martin et al. 2012).
|Habitat and Ecology:|
Pipistrellus murrayi roosted 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), many of which were heavily decayed and collapsed soon after (Lumsden et al. 2007). Females formed colonies of up to approximately 50 individuals, while males often roosted solitarily (Lumsden et al. 1999, 2007). Generation length of this species was likely to be 4-5 years. This species roosted 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 foraged 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 fed on a range of small flying invertebrates, predominantly moths, beetles, and flying ants (Lumsden and Schulz 2009).
The reasons for the decline and ultimate extinction of P. murrayi remain unclear. While habitat loss may have caused some declines in the past, 75% of Christmas Island is covered by primary or secondary rainforest, with little change in the amount of available habitat during the period of decline. Furthermore, most of the species’ range was within a National Park. The major threats to the species may have included predation or disturbance to bats within their roosts from introduced species, e.g. Common Wolf Snake (Lycodon capucinus), Feral Cat (Felis catus), Black Rat (Rattus rattus) and Giant Centipede (Scolopendra subspinipes) (Lumsden et al. 2007). Although not considered the primary cause of decline, as the spatio-temporal pattern did not closely match the pipistrelle’s decline, a series of recent population explosions of Yellow Crazy Ants (Anoplolepis gracilipes) is likely to have led to some habitat change, likely decline in invertebrate prey resources, and may also have disturbed individuals at roost sites. It is also possible that some disease may have contributed to the decline, however, individuals captured over the period of decline appeared to be in good health, with the exception of low white blood cell counts, although the significance of these findings was unclear (Lumsden et al. 2007). Even the last known individual appeared to behave normally before it vanished.
Pipistrellus murrayi is now extinct, as exhaustive surveys, using techniques that previously reliably detected the species, have been undertaken without success throughout its previously known range at appropriate times, habitat and locations, and over an appropriate time frame. A Recovery Plan for this species was prepared in 2004 (Schulz and Lumsden 2004). The plan’s implementation was reviewed by James and Retallick (2007), who considered that most actions had been implemented, although not sufficiently to determine the cause of the decline.
|Citation:||Lumsden, L., Racey, P.A. & Hutson, A.M. 2017. Pipistrellus murrayi. The IUCN Red List of Threatened Species 2017: e.T136769A518894.Downloaded on 17 August 2018.|
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