92 USGS/BRD/ITR-2000-0012 



large discrepancies. At six sites compared, Ecological 

 Consulting Incorporated reported much greater numbers 

 at three sites (range, 280-7630%), much lower numbers 

 at one site (750%), and hundreds of murres at two sites 

 (not colonies) where USFWS surveys found none. 

 Differences between surveys were so large that other 

 factors also may have been involved (e.g., colony 

 misidentifications, extensive variation in numbers of 

 murres attending colonies, or possible colony 

 disturbances). 



British Columbia 



The only large murre colony in British Columbia 

 is at Triangle Island. In 1989, an extensive study was 

 undertaken to provide the only reliable and complete 

 estimate to date (Rodway 1990). This study used ground 

 photographs, telescope counts, and boat counts to 



provide complete coverage of the colony and used 

 breeding phenology, attendance patterns, and k 

 correction factors from several plots in the colony to 

 estimate the 1989 colony size (P) using the formula 

 P = k (Tr + C) where k - ratio of breeding sites to total 

 birds present on study areas (i.e., equivalent to a k 

 correction factor), T = total mean count from 

 photographs of the colony, r = ratio of telescope to 

 photographic counts on the study plot; and C = count 

 from the top of Puffin Rock of birds that were obscured 

 from the water. In 1989, Rodway (1990) calculated a 

 mean k value of 0.41 (range, 0.39-0.53) using the 

 formula presented in Birkhead and Nettleship (1980). 

 This value is comparable to a k f correction factor value 

 of 0.82, using the equation presented under California 

 methods. Rodway (1990) noted that his k value was 

 much lower than that reported for other Pacific and 

 Atlantic colonies. 



