5. If density (number of nests/unit area) is required, the colony area 

 can be determined either by surveying, measuring from aerial photographs (see 

 Portnoy 1977), or, as a gross approximation, by multiplying the total length 

 of the colony by the average of all belt transect lengths. 



6. To provide a measure of sampling accuracy, the individual belt tran- 

 sect densities can be calculated and used to derive confidence limits in each 

 colony (Portnoy 1977). 



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