282 NORTH AMERICAN FAUNA 61, FISH AND WILDLIFE SERVICE 

 Reproduction 



Sea otter breeding was observed once in Aleutian waters. It 

 took place in the water, as the pair rolled over and over, some- 

 times being at the surface, sometimes underneath, the male grasp- 

 ing the female at the head with his teeth. This was on July 23, 

 1936, at a time when the female had a small dependent pup. The 

 pup had been left at the outer edge of the kelp patch, where it 

 swam about calling for its mother. This circumstance indicates 

 that the female may breed in successive years. Scammon (1874) 

 remarks that the gestation period is supposed to be 8 or 9 months. 

 Probably it is fully that long. 



Many observers agree that breeding may take place at almost 

 any time of the year, because young of different ages can be 

 seen at any season. Fisher (1940) appears to have definitely 

 noted this during her research on the California sea otter. It is 

 known that the young are born on the kelp beds, but in Alaskan 

 waters, /where kelp beds disappear during the winter, the pro- 

 cedure is uncertain. Herendeen (1892) claims that the young 

 are born at sea — he did not mention kelp beds. 



Food Habits 



It is well established that the northern sea otter feeds largely 

 on sea urchins, and that this diet is supplemented by considerable 

 quantities of mollusks, including mussels, chitons, limpets, snails, 

 and others; and with lesser quantities of crabs, octopuses, and 

 other items — fish play a minor role in the diet. More detailed 

 analyses of the diet of the northern sea otter are given by 

 Williams (1938), Barabash-Nikiforov (1935), and Murie (1940). 



Although the sea otter has, to a large extent, forsaken fish as 

 an important item in the diet, apparently it still enjoys such food 

 on occasion. Chase Littlejohn (1916) reports an interesting inci- 

 dent: A sea otter was seen approaching his ship, but it dived. 

 Presently, a fisherman pulled in a codfish and, as the fish came 

 to the surface, the sea otter was seen clasping it in its paws. 



One feature of the feeding habits deserves special mention, 

 because it involves the use of tools. It was first seen in detail 

 in California (Fisher 1939, and Murie 1940). Briefly stated, the 

 sea otter dove for food and when it came to the surface the 

 observer saw a rock lying on its chest or abdomen. The animal 

 held a small mussel (or whatever the food morsel might be in 

 such instances) in both paws and pounded it on the rock to 

 break it. When feeding, the sea otter has a habit of rolling over 

 occasionally in a complete turn, then continuing with its repast. 

 Sometimes, it performs this roll with a rock and mollusk both 



