124 NORTH AMERICAN FAUNA 68 



Table 16. — Analysis of 422 fecal samples from Amchitka Island, February 



to April 1959 



[The samples were examined on seven habitually used hauling-out beaches] 





Number of 



Percent of 





occurrences 



fecal samples 



Food organism i 



(frequency) 2 



having item 



Arthropoda : 







Crabs (Crustacea) 



67 



16 



MoUusca: 







Chitons (Amphineura) 



26 



6 



Snails ( Gastropoda ) - 



11 



3 



Limpets Acmea 



10 



3 



Horse mussel Volsella volsella „ 



89 



21 



Mussel Mytilus edidus 



1 



<1 



Varnished horse mussel Musculus vevnicosa . 



48 



11 



Pearly monia Pododesmus macrochisma 



1 



<1 



Clam (Pelecypoda) 



5 



1 



Pecten ( Pelecypoda ) — 



1 



<1 



Octopus (Cephalopoda) 



3 



1 



Subtotal 



195 



46 



Echinodermata : ^ 







Sea urchin Strongylocentrotus drobachiensis 



401 



95 



Chordata : 







Fish 



63 



15 



Total 



726 





1 Nonfood material, clay, gravel, etc., was found in seven fecal samples. 



2 Frequency refers to the number of samples having the item, not the number of individuals 

 present. 



2 Starfish were probably broken into fine pieces and thus not detected. 



information concerning the food habits of sea otters but, because 

 hard parts of some food species are not ingested, information de- 

 rived from fecal examination contributes distorted information 

 on both the qualitative and quantitative aspects of food habits. 



Otters must defecate on land if fecal samples are to be studied 

 In many areas otters defecate on land infrequently or not at all. 

 Weather conditions, geographical features (such as sheltered i 

 beaches above the tide line), and the presence of a human popu- | 

 lation appear to influence the frequency with which sea otters haul \ 

 out on land. Like all other marine mammals, and unlike many I 

 terrestrial ones, the sea otter is not selective in choosing a de- 

 fecation site. When sleeping or resting on land, the otter usually 

 rises to its feet and expels the feces at the edge of its resting 

 place. As it changes position for comfort during several hours on 

 shore, feces may be deposited in several locations around the rest- 

 ing spot and the animal may, in changing position, lie in its own 

 feces. Defecation in the water is also a random function and may 

 occur while the animal is eating, swimming, or resting on its back 

 on the surface. Although, as noted above, defecation on land is 

 frequent, I have often noted that captive otters, after a rest period 

 beside their pool, may defecate immediately upon entering the j 

 water. I 



