INTERRELATIONS BETWEEN SEABIRDS AND INTRODUCED ANIMALS 225 



arctic foxes were introduced on almost every 

 island from the Aleutians to Prince William 

 Sound, and on some of the islands in south- 

 eastern Alaska. The Aleutian Islands Na- 

 tional Wildlife Refuge maintained records 

 from which the above figures are quoted, but 

 though records of other islands' use for fur 

 farms exist in the archives of the Alaska 

 Game Commission, no record of the fur values 

 was kept. 



Murie (1959) assessed the influence of the 

 foxes by examining 2,501 fox droppings col- 

 lected in 1936 and 1937 from 22 of the Aleu- 

 tian Islands. He reported 57.8% of the food 

 items in these droppings was avian 48.9% 

 seabirds. The result of his investigations was 

 the adoption of new policies governing is- 

 suance of permits for fox farming in the 

 Refuge. The essential feature of these policies 

 was the revocation of certain existing per- 

 mits, with a view to reserving the islands con- 

 cerned for wildlife use. The decision proved 

 academic, for fur prices declined until no mar- 

 ket for Aleutian arctic fox pelts could be 

 found. But the foxes remained. 



The most obvious damage has been the 

 nearly complete extermination of the Aleu- 

 tian Canada goose (Branta canadensis leuco- 

 pareia). It has vanished from its former nest- 

 ing range in the Aleutian and Kuril Islands, 

 except for Buldir Island in the western Aleu- 

 tians (Jones 1963). Clark (1910) described this 

 goose as extremely abundant on Agattu Is- 

 land in 1909; however, foxes from Attu were 

 introduced there in 1923, 1925, and 1929. 

 Murie (1959) found "probably less than six 

 pairs" in 4 days of traveling over the island in 

 1937. 



In our main area of interest, cats appear to 

 have been widely introduced, but we found no 

 record of extensive predation on marine birds. 

 Jehl (1972) attributed the extinction of the 

 Guadalupe petrel to predation by cats, in com- 

 bination with the destruction of vegetation by 

 goats. Imber (1974) reported that "serious 

 predation by cats upon a colony of gray-faced 

 petrels on Little Barrier Island, New Zealand 

 was observed in 1950. Since that time, the 

 colony has become extinct." 



Though feral dogs are reported present on 

 islands in our area of interest, they do not ap- 

 pear to have significant influence on seabirds. 

 On Attu Island, the pet dogs of personnel of 



the Coast Guard LORAN station are reported 

 to take common eiders (Somateria 

 mollissima). 



Conclusions 



Ecological consequences of animal introduc- 

 tions to islands are rarely well documented. 

 Usually no thought is devoted to such conse- 

 quences until redress becomes difficult or 

 quite impossible. Many of the introductions 

 stem from a period before ecological under- 

 standing, and the introduced animal has ac- 

 quired the status of a native. The arctic fox in 

 the Aleutians fits all of these conditions. Until 

 we conducted a thorough search of the litera- 

 ture, some of it difficult to secure and written 

 in several languages, the original status of 

 this animal was not known. Its elimination, 

 now under way on selected islands, is difficult 

 and expensive. Rapid recovery of some avian 

 species, including certain passerines, has been 

 observed. However, ecological homeostasis is 

 the product of evolution, and restoration in 

 the Aleutians must follow that course. It is 

 not likely to proceed rapidly to a point 

 thought desirable by man. The accidental in- 

 troductions of animals such as rats and black 

 flies in the Aleutians constitute particularly 

 irksome events because they cannot be re- 

 versed. The new ecology of Amchitka, from 

 which the foxes have been removed, must 

 evolve in the presence of these species. Its 

 face will look very different than if they were 

 not there. We would like to suggest a means 

 by which such introductions may be pre- 

 vented, but it seems likely that more, not less, 

 can be expected. 



Preventing the introduction of ungulates 

 seems more likely to be successful, especially 

 if the islands lie within a National Wildlife 

 Refuge. Even this, however, becomes less cer- 

 tain with an expanding human population 

 and, with it, demands for more land on which 

 to produce food. 



Legal restrictions have been suggested as a 

 means to control or prevent introductions, 

 but in the northern islands, little enforcement 

 is likely. There is a phrase bearing on this, 

 said to have governed human behavior in the 

 early years of Caucasoid occupation of the 

 Aleutian Islands, "Heaven is too high and the 

 Czar too far away." 



