INTRODUCTION 



Much can be learned about the natural history of marine birds and 

 mammals through the systematic study of beach-cast specimens. The first 

 step in such investigations is the correct identification of the carcasses 

 and to that end this manual was prepared. Identifying a dead animal pre- 

 sents problems different from those confronted when identifying a live 

 one. For the latter, many field guides exist but they depend to a great 

 extent on knowledge of behavior and on characteristics observable from a 

 distance. When confronted with a dead animal, close at hand such clues 

 are no longer useful. This manual contains the necessary clues to iden- 

 tify dead marine birds and mammals occurring along the North American 

 west coast. 



The beach-cast specimen can provide insight into a species' anatomy, 

 physiology, diet, diseases, natural/unatural causes of mortality, and 

 other aspects of its natural history. In cases of rare, endangered or 

 infrequently encountered species, a beach-cast specimen becomes an in- 

 valuable source of information that would otherwise be impossible to 

 collect. In the cases of more abundant species, still more can be learn- 

 ed by accumulating over the long term, carefully tabulated records of 

 beach-case carcasses (see BEACHED BIRD AND MAMMAL SURVEYS). As a start, 

 the seasonal patterns of occurrence are revealed. Taken with environ- 

 mental information, large yearly differences in occurrence patterns help 

 to indicate the factors that affect the distribution of marine species. 

 Similar information can be gathered by direct at-sea observations. This, 

 however, is an extremely expensive and time consuming operation, so much 

 so that only one or two years of direct censuses are usually possible. 

 At-sea observations are also much more difficult to repeat and standardize. 

 The two activities though are complementary because the direct censuses 

 serve to calibrate the beach surveys, both of which after all provide 

 largely an index to a species occurrence and abundance. 



BEACHED BIRD AND MAMMAL SURVEYS 



Systematic censuses of carcasses on a beach or beaches can yield sur- 

 prisingly interesting and useful information. To be systematic, censuses 

 need to be made of the same stretch of beach at regular, periodic inter- 

 vals over an extended period. So useful is the information that major 

 projects have been organized in Great Britain, New Zealand and Australia 

 for a number of years, and more recently in the United States and else- 

 where. In some cases, the projects are conducted by government wildlife 

 department personnel and in others by private institutions using volunteer 

 workers. The information gathered is extremely useful in the conservation 

 of marine animals and in just increasing our knowledge about them. Unfor- 

 tunately, the information has also become useful in assessing the mortality 

 of animals due to man's activities, for instance, in the case of oil spills. 



