FAUNA OF THE ALEUTIAN ISLANDS AND ALASKA PENINSULA 325 



tions have a peculiar interest, because of possible adaptation to a 

 rodent-free environment. We do not have specific information for 

 Unalaska Island, where presumably the house mouse must have 

 been introduced in the settlemsnt. In the western, rodent-free is- 

 lands we took pains to study this question and found a single rec- 

 ord — on Kiska Island. In the summer of 1937, signs of mice were 

 found in a cabin on Kiska Island and many traps were set. A sin- 

 gle house mouse was caught, possibly the only one on the island, 

 though since the occupation of the Aleutians by military forces 

 it is to be expected that mice and rats have been brought to this 

 and other islands. 



The mouse from Kiska evidently came from Seattle in freight 

 shipments. It proved to be Mus musculus domesticus, rather than 

 a form from the Asiatic side. Schwartz and Schwartz (1943, p. 66) 

 have shown that the West European house mouse, from which 

 our American commensal mice were derived, is M. m. domesticus, 

 and not M. m. musculus as heretofore assumed. 



Rattus norvegicus: House Rat 



Russian: Krisi 



Rats were introduced in the Aleutian Islands during the 

 Russian occupation. Rat Island had received its name from the 

 Russians as early as 1790, hence the rats must have arrived at an 

 earlier date. Rats also are found at Unalaska and at Atka. 

 At Atka Village, the rats were very troublesome. The natives could 

 not raise gardens at Atka because of these pests, so they crossed 

 over to rat-free Amlia Island and planted their gardens. The 

 rats have managed to cross over to the little islands in Nazan 

 Bay, and they may soon invade Amlia Island (if they have not 

 already done so since the military occupation of that island). 

 Rats are reported from Kiska by G. A. Amman (correspondence) . 

 They were not there before World War II. It is probable that 

 rats have been introduced to Attu, Amchitka, and Adak as a 

 result of military operations. 



In addition to Atka Village, rats have become feral on both 

 Atka and Rat Islands. On Atka Island, we found their runways 

 in the heavy grass, and we saw cut plant stems, which were much 

 like those of Microius, but longer. Burrows were found in some 

 places. In the spring, we found large areas where the rats had 

 dug up the bulbs of Fritillaria camschatcensis, and Scheffer found 

 that the rats had eaten the basal parts of the stems of Anemone 



