THE SEA OTTER IN THE EASTERN PACIFIC OCEAN 103 



by sea otters but our fishing operations indicated that fish popu- 

 lations at Amchitka are large. Also, sea otters tend to feed on 

 sedentary fish that were not found in seal stomachs. 



Steller sea lions seldom chose places that were favored by sea 

 otters for resting on land. When sea lions passed near sea otters 

 that were diving for food, the otters usually raised themselves 

 high in the water to stare at the sea lions. Otherwise the two 

 species ignored each other. 



Parasitic worms (Terranova decipiens, for example) which com- 

 monly infest the harbor seal and sea lion, enter the encysted stage 

 in fishes. Sea otters that eat fish also become infested. Halarachne 

 miroungae, a nasal mite commonly found in harbor seals, were 

 rarely found in wild sea otters. These may have been picked up by 

 the sea otters at a location commonly used by the two species. 

 In the wild these pinniped parasites seemed not to seriously affect 

 sea otters. 



Glaucous-winged Gulls frequently obtained scraps from otters 

 while they fed on fish. I did not see gulls attempt to take fish 

 away from a feeding otter but they swam close to feeding otters 

 or hovered above them ready to take scraps (fig. 58). When we 

 were searching for sea otters during census studies, we found 

 that gulls were a useful indicator of the location of feeding otters. 

 A group of gulls sitting together on the water usually marked 

 the location where an otter would emerge from a food-gathering 

 dive. 



Unlike many other mammals, sea otters at Amchitka did not 

 appear to recognize the calls of birds as possible indicators of 

 approaching danger. On a number of occasions. Black Oyster- 

 catchers (Haematopus bachmani) and Emperor Geese (Philacte 

 canagica) were alarmed by our approach when we were stalking 

 sea otters that were hauled out on the beach. Although the calling 

 birds sometimes flew directly over the otters, they appeared to 

 pay little or no attention to them. 



Rats (Rattus norvegicus) introduced to Amchitka during World 

 War II often entered the sea otter enclosure to search for food 

 scraps. On one occasion a rat approached a sea otter that was 

 grooming its fur while resting on its back beside the pool. After 

 sniffing at the sea otter's side, the rat suddenly jumped onto the 

 otter's chest. Quickly the otter struck the rat with its forepaw, 

 knocking it a distance of nearly a meter. 



In general, it did not appear that the sea otter was in serious 

 competition with other mammal and bird species within its environ- 



