SHIP- AND WIND-BORNE COLONISTS 305 



to the south of Puhi Tikus, but on Pulu Tikus itself they never 

 gained a footing, and the " original " rats of that island remain 

 quite distinct from the new-comers. The bad habits of the 

 invaders rapidly became notorious, and, unlike the " original " 

 rat, which did very little damage, they soon became the source 

 of the most real economical loss to the islands. 



The rats of Pulu Tikus have always been in the habit of 

 climbing the coconut palms, and in some cases their offspring 

 are reared in the crown of a palm some seventy feet from the 

 ground ; and they have learned to open the ripe nuts which 

 have dropped from the palms — for coconut constitutes practi- 

 cally the whole of their dietary. 



But the Robert Portner rats were not content with this, 

 and when they had become accustomed to climbing the palms, 

 they learned to attack the nuts whilst they were still green. 

 To-day, thousands of nuts must be ruined daily by being 

 nibbled, just where the stalk joins the husk, and a nut that is 

 attacked in this way falls from the palm, and is quite useless 

 for any purpose. It seems a strange thing that these new rats 

 should so quickly have learned this mischievous practice, when 

 the members of the older colony still remain contented with 

 the nuts that fall naturally. 



On one of the islands of the atoll ring the whole colony of 

 rats consists of black rats, and stragglers of this species are 

 found in some of the other islands ; but the Robert Portmr 

 rat is the common brown rat, and the Pulu Tikus colony is 

 probably composed of a variety of the same species. 



Mice have become fairly abundant in some islands, and 

 they do a considerable amount of damage to the stores, but, 

 although they have no great struggle against enemies, they 

 do not appear to increase much, and their importance, when 

 compared with that of the rats, is practically nil. 



The next most conspicuous additions to the fauna made 

 accidentally by ships and merchandise, are the centipedes and 

 scorpions. 



The great centipedes have become exceedingly numerous, 

 and they have spread to all the islands ; and the scorpions exist 



