Christmas Island shrew

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Christmas Island shrew
Status iucn3.1 CR.svg
Critically endangered, possibly extinct  (IUCN 3.1) [1]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Eulipotyphla
Family: Soricidae
Genus: Crocidura
Species:
C. trichura
Binomial name
Crocidura trichura
Dobson, 1889
Christmas Island Shrew area.png
Christmas Island shrew range
Synonyms

Crocidura fuliginosa trichura
Crocidura attenuata trichura

Contents

The Christmas Island shrew (Crocidura trichura), also known as the Christmas Island musk-shrew is an extremely rare or possibly extinct shrew from Christmas Island. It was variously placed as subspecies of the Asian gray shrew (Crocidura attenuata) or the Southeast Asian shrew (Crocidura fuliginosa), [2] but morphological differences and the large distance between the species indicate that it is an entirely distinct species. [3]

Description

The Christmas Island shrew, like other members of the genus Crocidura, is a small short-legged mammal with a distinct pointed muzzle. It has a dark grey to reddish brown colouring. Like all other shrews, the Christmas Island shrew resembles a mouse and weighs in a range between 4.5–6 g (0.16–0.21 oz). [4] The Christmas Island shrew varies from other forms of the species in that it is beset with long fine hairs, and its tail is much greater in length. [5] The typical lifespan for its genus is approximately one year, but Crocidurine shrews have been reported to live for up to two years in the wild. [6]

Habitat

The Christmas Island shrew is a terrestrial animal that occupies tall plateau rainforests with deep soil, as well as the shallow soil of terrace rainforests. It remains unknown if the species can live in secondary growth. This shrew feeds primarily on small beetles and uses holes in rocks and tree roots for shelter. [1]

Status

The most recent specimens of C. trichura were found in 1985, and a survey conducted fifteen years later failed to find any individuals. The current population trend is unknown. [1]

According to Version 3.1 of the IUCN's criteria for critically endangered, endangered, and vulnerable species, C. trichura is critically endangered and possibly extinct. [1]

Causes of endangerment

There is conclusive evidence that Crocidura trichura has declined dramatically since 1900, yet the reason is unproven. After an unconfirmed sighting in 1958, it was rediscovered in 1985 when two specimens were caught. The two individuals later died. Several unconfirmed reports occurred between 1996 and 1998 but a survey undertaken in 2000 failed to find any individuals. [7] The reasons for the population's reduction are unknown but potential threats include disease, habitat loss, habitat alteration due to invasive weeds, predation from species such as cats and black rats, small population size, and mortality from road traffic. [1] Its disappearance in recent times might be caused by the accidentally introduced yellow crazy ant (Anoplolepis gracilipes), which is a dangerous threat for many terrestrial animals on Christmas Island. [7]

Trypanosoma disease

The theory of Durham (1908) and Pickering and Norris (1996) report that the decline of two endemic rats may be attributed to the infection of the Christmas Island shrew, according to local researchers. This forest dwelling mammal was at first thought to have vanished by 1908, probably due to a trypanosoma disease carried by introduced black rats, which is also considered a likely cause of the extinctions of Maclear's rat and the bulldog rat. [7] The initial drop in C. trichura’s population size occurred around the same time as the introduction of the Rattus rattus (the black rat), which carried a murid trypanosome. Evidence of the black rat and/or the parasite causing the Christmas Island shrew's population decline is not solid. [8]

Gecarcoidea natalis

Another theory on the decline of Crocidura trichura is linked to the demise of the two endemic rats, and the competition left amongst the Christmas Island shrew and the Christmas Island red crab (Gecarcoidea natalis) for leaf litter resources. The decline of predator rat species allowed for the quickened rise of G. natalis, a usual prey of the rats. [9] This could have forced C. trichura into new habitats such as tree canopies, or sites with low crab abundances. The population of C. trichura may have been pressured by their vulnerability during weaning. [10] They left the nest immediately and tended to aimlessly wander as juveniles, making them vulnerable to predation by crabs.

Recovery

The Australian Government has adopted a recovery plan for the Christmas Island shrew consisting of two stages of objectives. [4]

Stage 1: [7]

Stage 2: [7]

The Australian Government also believes that habitat protection from or eradication of the Yellow Crazy Ant is vital in order for the species to fully recover. The Yellow Ant is known to be extremely destructive to the ecosystem on Christmas Island, often killing land crabs, endemic reptiles, and a wide range of native invertebrate. The Yellow Crazy Ants are believed to be a danger to all mammals, birds, and reptiles on the island because the ants either act as predators to the species or deplete its resources and destroy the habitat in which the species lives, causing loss of life in both scenarios. [11]

Related Research Articles

<span class="mw-page-title-main">Black rat</span> Species of rodent

The black rat, also known as the roof rat, ship rat, or house rat, is a common long-tailed rodent of the stereotypical rat genus Rattus, in the subfamily Murinae. It likely originated in the Indian subcontinent, but is now found worldwide.

<span class="mw-page-title-main">Christmas Island red crab</span> Species of crustacean (Gecarcoidea natalis)

The Christmas Island red crab is a species of land crab that is endemic to Christmas Island and Cocos (Keeling) Islands in the Indian Ocean. Although restricted to a relatively small area, an estimated 43.7 million adult red crabs once lived on Christmas Island alone, but the accidental introduction of the yellow crazy ant is believed to have killed about 10–15 million of these in recent years. Christmas Island red crabs make an annual mass migration to the sea to lay their eggs in the ocean. Although its population is under great assault by the ants, as of 2020 the red crab had not been assessed by the International Union for Conservation of Nature (IUCN) and it was not listed on their Red List. The crab's annual mass migration to the sea for spawning is described as an "epic" event. Millions emerge at the same time, halting road traffic and covering the ground in a thick carpet of crabs.

<span class="mw-page-title-main">Maclear's rat</span> Extinct species of rodent

Maclear's rat is an extinct large rat endemic to Christmas Island in the Indian Ocean. It was one of two species of rat native to Christmas Island, alongside the bulldog rat. Abundant, unfamiliar with and seemingly unafraid of humans, large numbers of the creatures emerged and foraged in all directions at night. Making querulous squeaks, the rats entered the Challenger expedition's tents and shelters in 1886, ran over sleepers, and upset everything in the search and fight for food. Maclear's rat might have been responsible for keeping the population of the Christmas Island red crab in check, as recent numbers of the crab are greater than in the past. It is thought that black rats inadvertently introduced by the expedition infected the Maclear's rats with a disease, which in turn could have contributed to the species' decline. The last recorded sighting was in 1903, although it is possible that Maclear's rats hybridized with black rats. A hard tick, described as an ectoparasite of Maclear's rat, is also thought to be extinct.

<span class="mw-page-title-main">Threatened fauna of Australia</span> Animals at risk of becoming extinct

Threatened fauna of Australia are those species and subspecies of birds, fish, frogs, insects, mammals, molluscs, crustaceans, and reptiles to be found in Australia that are in danger of becoming extinct. This article lists species classified as threatened species under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999.

<span class="mw-page-title-main">Christmas imperial pigeon</span> Species of bird

The Christmas imperial pigeon or Christmas Island imperial pigeon, also known as Black imperial pigeon, Dusky imperial pigeon, Wharton's imperial pigeon, or burong pergam, is a large imperial pigeon endemic to Christmas Island in the northeastern Indian Ocean. It has an overall grey-blue colouration, and juveniles are duller than adults. It makes a soft purring coo sound and a deeper whoo sound comparable to a cow mooing. It lays one glossy white egg per brood, and is possibly somewhat colonial.

<span class="mw-page-title-main">Pale field rat</span> Species of rodent

The pale field rat is a small rat endemic to Australia. It is a nocturnal and herbivorous rodent that resides throughout the day in shallow burrows made in loose sand. Once widespread, its range has become greatly reduced and it is restricted to the grasslands, sedges, and cane-fields at the north and east of the continent. Its fur is an attractive yellow-brown colour, with grey or cream at the underside. This medium-sized rat has a tail shorter than its body.

<span class="mw-page-title-main">Christmas boobook</span> Species of owl

The Christmas boobook, also known more specifically as the Christmas Island hawk-owl, is a species of owl in the family Strigidae.

<span class="mw-page-title-main">Christmas white-eye</span> Species of bird

The Christmas white-eye is a species of bird in the family Zosteropidae. It is endemic to Christmas Island. Its natural habitats are tropical and subtropical moist broadleaf forests and subtropical or tropical moist shrubland. It is threatened by habitat destruction.

<span class="mw-page-title-main">Christmas Island National Park</span> Protected area in Australia

Christmas Island National Park is a national park occupying most of Christmas Island, an Australian territory in the Indian Ocean southwest of Indonesia. The park is home to many species of animal and plant life, including the eponymous red crab, whose annual migration sees around 100 million crabs move to the sea to spawn. Christmas Island is the only nesting place for the endangered Abbott's booby and critically endangered Christmas Island frigatebird, and the wide range of other endemic species makes the island of significant interest to the scientific community.

<span class="mw-page-title-main">Christmas goshawk</span> Subspecies of bird

The Christmas goshawk or Christmas Island goshawk is a bird of prey in the goshawk and sparrowhawk family Accipitridae. It is a threatened endemic of Christmas Island, an Australian territory in the eastern Indian Ocean.

<span class="mw-page-title-main">Christmas Island flying fox</span> Species of mammal (bat)

The Christmas Island flying fox or Christmas Island fruit bat, as the name suggests, is a flying fox endemic to Christmas Island. It is unclear if it should be considered a distinct species, or a subspecies of the black-eared flying fox. It may descend from a population of island flying foxes from Pulau Panjang near Java.

<span class="mw-page-title-main">Wildlife of Christmas Island</span>

The wildlife of Christmas Island is composed of the flora and fauna of this isolated island in the tropical Indian Ocean. Christmas Island is the summit plateau of an underwater volcano. It is mostly clad in tropical rainforest and has karst, cliffs, wetlands, coasts and sea. It is a small island with a land area of 135 km2 (52 sq mi), 63% of which has been declared a National park. Most of the rainforest remains intact and supports a large range of endemic species of animals and plants.

<span class="mw-page-title-main">Rattini</span>

Rattini is a very large, diverse tribe of muroid rodents in the subfamily Murinae. They are found throughout Asia and Australasia, with a few species ranging into Europe and northern Africa. The most well-known members of this group are the true rats, several species of which have been introduced worldwide.

References

  1. 1 2 3 4 5 Woinarski, J.; Burbidge, A.A.; Lumsden, L. (2016). "Crocidura trichura". IUCN Red List of Threatened Species . 2016: e.T136379A22304640. doi: 10.2305/IUCN.UK.2016-3.RLTS.T136379A22304640.en . Retrieved 12 November 2021.
  2. Francis Harper (1945). Extinct and Vanishing Mammals of the Old World. New York, American Committee for International Wild Life Protection.
  3. Rainer Hutterer (2005). "Crocidura trichura". In D. E. Wilson; D. M. Reeder (eds.). Mammal Species of the World. Johns Hopkins University Press.
  4. 1 2 "Crocidura trichura — Christmas Island Shrew". www.environment.gov.au. Commonwealth of Australia: Department of the Environment. Retrieved 2015-10-29.
  5. Andrews, C. W. 1900. A Monograph of Christmas Island (Indian Ocean). British Museum of Natural History, London, UK.
  6. Meek, Paul (2000). "The Decline and Current Status of the Christmas Island Shrew". Australian Mammalogy. 22 (1): 43-49. doi:10.1071/AM00043.
  7. 1 2 3 4 5 Michael Schulz (2004). National Recovery Plan for the Christmas Island Shrew Crocidura attenuata trichura (PDF). Canberra: Department of the Environment and Heritage. p. 23.
  8. Eldridge, Mark D. B.; Meek, Paul D.; Johnson, Rebecca N. (2014). "Taxonomic Uncertainty and the Loss of Biodiversity on Christmas Island, Indian Ocean". Conservation Biology. 28 (2): 572–579. doi: 10.1111/cobi.12177 . PMID   24283832.
  9. Meek, Paul (2000). "The Decline and Current Status of the Christmas Island Shrew" (PDF). Australian Mammalogy.
  10. "Full text of "The mammals of China and Mongolia"". archive.org. Retrieved 2015-10-29.
  11. "Invasion of the yellow crazy ant – key threatening process listing | NSW Environment & Heritage". www.environment.nsw.gov.au. Retrieved 2015-10-29.