This species is listed as Extinct because it has not been recorded since 1904, and extensive searches in the intervening years have failed to locate it.

Maclear's Rat (Rattus macleari) 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.

Maclear's Rat became extinct probably between 1900 and 1904 (Green 2014). It was abundant on Christmas Island at the close of the 19^th century. Lister visited the island in 1887 and said of Maclear's Rat, it "abounds all over the island" (Lister 1888). Andrews (1900) who was on the island for ten months, 1897-1898, noted that it was "by far the commonest of the mammals found in the island; in every part I visited, it occurred in swarms. During the day nothing is to be seen of it, but soon after sunset numbers may be seen running about in all directions".

Maclear’s Rat was nocturnal, and had little fear of people. It was present all over Christmas Island, which was at the time mostly covered by tropical rainforest. Lister (1888) noted that "they generally keep to the ground, but are able to climb trees". Andrews (1900), who apparently was more impressed by their climbing ability, said they "ascend trees to a great height" in pursuit of fruits and young shoots, and "I have often seen them run up the trailing stems of the lianas, and, in fact, they can climb as well as a squirrel". Little is known of their diet, except that they were fond of fruits and young shoots. Andrews (1900) also noted that "In the daytime these rats live in holes among the roots of trees, in decaying logs, and shallow burrows. They seem to breed all the year round."

Maclear's Rat was abundant in 1897-1898 while Andrews was on Christmas Island (Andrews 1900). By the time he returned to the island in 1908, he was confident that it and the other native rat species, the Bulldog Rat Rattus nativitatis, were extinct (Andrews 1909). Andrews (1909) speculated that introduced Black Rats Rattus rattus had brought an epidemic disease to the island that wiped out both native rats. Nearly 100 years later, the mystery was finally solved by Wyatt et al. (2008), who used ancient DNA methods on samples from museum specimens of these rodents collected during the extinction window (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).

To Andrews, the disappearance of such an abundant animal in such a short time had to be due to disease because R. rattus was not present over the entire island. It was unreasonable therefore to assume that the native species had been out-competed by R. rattus all over the island (Andrews 1909). Two predators had been introduced to the island by 1908, cat and dog, but these were far too few to rid the island of the rats (Andrews 1900, 1909). Although Christmas Island had an increasing human settlement at Flying Fish Cove, roads now crossed the island, and there was active phosphate mining, most of the original forest remained and even collectively these human disturbances were unlikely to have caused significant declines in the populations of Maclear's Rat (Andrews 1909). Andrews (1909) also 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.

Pickering and Norris (1996) report on documents concerning Maclear's Rat that were uncovered at Oxford University, and specimens from the Zoological Collections, University Museum, Oxford University and the University Museum of Zoology, Cambridge. The documents include notes for a lecture by K. R. Hanitsch who visited Christmas Island for five weeks in 1904 and was unable to locate either species of native rat. Dr. Durham, a pathologist, visited the island from November 1901 to March 1902, during which Durham collected 19 rat specimens. Pickering and Norris (1996) note that some of these specimens were of R. macleari, R. rattus, and some of varying degrees of hybrid between R. macleari and R. rattus. Hybridisation between the two species, with the implication that R. macleari was genetically swamped by R. rattus, was put forward as a contributing factor in the demise of R. macleari (Pickering and Norris 1996). However, hybridisation between the two species is implausible given the phylogenetic distance between them, and re-examination of specimens confirms that each belongs to one or the other species (Musser and Carleton 2005; Aplin and Rowe 2023). This is further supported by the molecular studies of Wyatt et al. (2008).

Because Durham collected specimens, some of which were R. macleari, in late 1901 and 1902, R. macleari must have become extinct after 1901.

McDougal was the last person to recall seeing native rats alive, albeit in the act of dying (Andrews 1909). These rats were probably R. macleari because R. nativitatis was the rarer of the two, as evidenced by the fact that Durham was unable to collect any specimens of R. nativitatis in 1901-1902. Andrews (1909) writes that McDougal's recollections are from 5-6 years before, but it is unclear whether he meant 5-6 years prior to his 1909 publication (putting the date at 1903-1904), or if it was 5-6 years prior to 1908 when Andrews was on Christmas Island (putting the date as 1902-1903 as Pickering and Norris (1996) interpret the anecdote). Green (2014) further defined the date of introduction of Black Rats (and hence trypanosomes) (September 1900) and the extinction of R. macleari (between April 1904 and October 1904).

There are no conservation measures pertaining to this species.