OIL VULNERABILITY INDEX FOR MARINE ORIENTED BIRDS 



235 



Table 2. Criteria and points used in calculating Oil Vulnerability Index. 



be needed, and where periodic project shut- 

 down could be called for. 



With these points in mind it is immediately 

 obvious that Southeast Alaska (Table 4), 

 which has only 9 high-score birds, offers far 

 less potential for bird problems than does the 

 Aleutian area (Table 5), which has 24 high- 

 score species. The planning agency could 

 make some immediate decisions on site priori- 

 ties and research funding based on such in- 

 formation. 



Discussion 



We are convinced that the OVI principle ex- 

 pressed here will become a useful manage- 

 ment tool with all sorts of possible applica- 

 tions. We recognize some difficulties with the 

 present version, but believe it is timely to pre- 

 sent the system so that a broader range of 

 thought, improvements, and application can 

 be applied to it. 



Of prime importance is the system's sim- 

 plicity. The use of four levels of value for each 

 factor, instead of five or more, is an attempt 

 to simplify. Ian McHarg (1969) has shown 

 that extremely complex land-use values can 

 be graphically compared and displayed by 

 using three levels in a way that is useful to 

 decision makers. The difficulty of using more 

 levels of value was indicated by Sparrowe and 

 Wight (1975) who used up to 10 levels, enor- 

 mously complicating the problem of dealing 

 with low-quality information, which is often 

 all that is available. The use of scores of 0, 1, 

 3, 5 instead of 0, 1, 2, 3 for 20 factors enabled 

 us to use the convenient 100 points instead of 

 60 points as the maximum potential total 

 score for any species. 



The 20 factors that were evaluated are ad- 

 mittedly arbitrary; with refinement and more 

 detailed data they could be adjusted to show 

 better separation between affected species. 

 The decision to use 20 factors instead of more 



