ORDER RODENTIA: RODENTS 209 



This rat apparently was less generally distributed over the island 

 than R. macleari, inhabiting hilly areas in the interior. Andrews 's 

 account supplies practically all that is known of it. He wrote: 



Though very numerous in places, especially on the hills, e. g. Phosphate 

 Hill, [it] is very much less common than M. macleari. I never saw one in 

 Flying Fish Cove [the settlement], though they certainly have been killed 

 there. 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. [It is a] much more sluggish animal than M. macleari, and unlike it, 

 never climbs trees; and it is difficult to avoid the belief that the former 

 species is being supplanted by the latter in spite of the abundance of food. 

 Both animals are strictly nocturnal, and M. nativitatis, when exposed to 

 bright daylight, seems to be in a half-dazed condition. The Ross family in 

 Christmas Island have given this species the name "Bull-dog Rat," and this 

 has been adopted by the Malays. 



This was in 1897. When, in 1908, Andrews revisited the island 

 to see what changes had followed the planting of a settlement there, 

 he found both species apparently quite gone. "In spite of continual 

 search, not a single specimen of either species could be found in any 

 part of the island." This disappearance, as detailed under Rattus 

 macleari, was conjectured to have taken place about five or six years 

 earlier, when the medical officer stationed there had frequently seen 

 individuals of the native rats "crawling about the paths in the day- 

 time, apparently in a dying condition." Andrews suggests that the 

 introduced Roof Rat, by then already present in considerable num- 

 bers, had brought in some epizootic disease to which the native 

 species had been susceptible, and in consequence they had been 

 entirely wiped out in the brief space of a few years. (Andrews, 1909, 

 pp. 101-102.) 



At the time of Andrews's first visit he wrote (1900) : "The con- 

 ditions of life are apparently extremely favourable, food being 

 always abundant, and the hawk and owl, which are the only possible 

 enemies [of these rats], feeding mainly on birds and insects. The 

 consequence of this is that all the species of mammals are extremely 

 common, and the individuals are always exceedingly fat. Perhaps 

 Mus [= Rattus] nativitatis, the bull-dog rat as the Cocos Islanders 

 have named it, is the least numerous, probably because of some 

 competition with the much more active and versatile M. macleari, 

 but most specimens of M. nativitatis have a layer of fat from half 

 to three-quarters of an inch thick over most of the dorsal surface 

 of the body." Possibly this very abundance of individuals and their 

 fat condition made them the more susceptible to any disease brought 

 in from outside. 



While conjecture as to the origin of the endemic fauna is more or 

 less futile, Andrews nevertheless points out that on the whole its 

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