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Rattus nativitatis 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Rodentia Muridae

Scientific Name: Rattus nativitatis (Thomas, 1889)
Common Name(s):
English Bulldog Rat, Christmas Island Burrowing Rat

Assessment Information [top]

Red List Category & Criteria: Extinct ver 3.1
Year Published: 2016
Date Assessed: 2015-05-28
Assessor(s): Lamoreux, J., Burbidge, A.A. & Woinarski, J.
Reviewer(s): Amori, G.
Contributor(s): Dickman, C.
Justification:
Listed as Extinct because it has not been recorded with certainty since 1897-1898, and extensive searches in the intervening years have failed to locate this species.
Previously published Red List assessments:

Geographic Range [top]

Range Description:The Bulldog Rat was endemic to Christmas Island, Australia. Christmas Island is approximately 135 km² and lies 345 km south of Java, the nearest landmass, in the Indian Ocean.
Countries occurrence:
Regionally extinct:
Christmas Island
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The Bulldog Rat became extinct probably between 1900 and 1904. This species was never as abundant as the other native rat to Christmas Island, Rattus macleari, which went extinct in 1904 (Green 2014). Two specimens were collected by Lister in 1887 (Thomas 1888), and a further nine specimens were collected by Andrews in 1897-1898 (Andrews 1900).
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:Little is known the habitat and ecology of the Bulldog Rat. Its short tail and robust hands and feet demonstrate that it was equipped for life as a fossorial species (Thomas 1888, Forsyth Major 1900). It is interesting, however, that its skull was described as "particularly small, slender, and delicate" (Thomas 1888).

In any case, the species was often seen in and around burrows, and, unlike R. macleari, it did not climb trees. Andrews (1900) summed up what he knew of the animal: "They seem to live in small colonies in burrows, often among the roots of a tree, and occasionally several may be found living in the long, hollow trunk of a fallen and half-decayed sago-palm (Arenga listeri). The food consists of wild fruits, young shoots, and, I believe, the bark of some trees."
Systems:Terrestrial

Threats [top]

Major Threat(s): This species was last recorded by Andrews from his 10 month stay on Christmas Island 1897-1898 (Andrews 1900). At that time, it already appeared to be in decline. Although the species was known from the settlement at Flying Fish Cove, Andrews never encountered them there and believed they were mainly confined to higher ground (Andrews 1900, 1909). In the hills, he described them as "very numerous in places", but less common than R. macleari (Andrews 1900). Andrews (1900) states that "it is difficult to avoid the belief that the former species [R. nativitatis] is being supplanted by the latter [R. macleari] in spite of the abundance of food."

By the time Andrews revisited the island in 1908, he was confident in pronouncing the species to be extinct (Andrews 1909). In 1904, Hanitsch visited the island hoping to collect specimens of the native rats, but was unable to locate either species (Pickering and Norris 1996; see account for R. macleari for further details). Durham visited the island in November of 1901 to March 1902 and collected R. macleari and R. rattus, but was unable to obtain R. nativitatis, despite offering a reward to the local inhabitants (Pickering and Norris 1996; see account for R. macleari for further details). Pickering and Norris (1996) note that Durham did not go far from Flying Fish Cove during his stay, thus he could well have missed R. nativitatis. However, Hanitsch's failure to obtain R. nativitatis in 1904 likely means that the species was extinct by this time. Andrews (1909) relates anecdotal information that a medical officer on the island, Dr. McDougal, recalled frequently seeing "individuals of the native species of rats crawling about the paths in the daytime, apparently in a dying condition" in 1902-1904, and these may have included R. nativitatis, but were likely to be R. macleari (see account for R. macleari for further details).

The demise of the Bulldog Rat was certainly rapid, going from locally common to extinct in less than eight years. It is thought to have been the result of an epidemic disease brought to the island by introduced Black Rats R. rattus (Andrews 1909; Aplin 2008). Black Rats are thought to have been introduced to the island by the S.S. Hindustan in 1899 (Pickering and Norris 1996) - subsequently determined to be September 1900 by Green (2014). This hypothesis is supported by the study of  Wyatt et al. (2008), who used ancient DNA methods on samples from museum specimens of these rodents collected during the extinction window (AD 1888–1908), and showed that endemic rats collected prior to the introduction of Black Rats were devoid of evidence of a pathogenic trypanosome (carried by fleas hosted on recently-introduced Black Rats).

Conservation Actions [top]

Conservation Actions: There are no conservation measures pertaining to this species.

Citation: Lamoreux, J., Burbidge, A.A. & Woinarski, J. 2016. Rattus nativitatis. The IUCN Red List of Threatened Species 2016: e.T19351A22443478. . Downloaded on 24 October 2017.
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