Ralph and Long 



Chapter 35 



Productivity in California-Observations At Sea 



used a grid placed over the skin to derive an average ratio of 

 dark:light overall coloration. In adults, for example, this 

 resulted in an overall ratio of 90: 10 dark:light. We feel that it 

 is more informative to break the data down by areas of the 

 body, since different feather tracts molt at different rates 

 (Carter and Stein, this volume). 



Characterization of plumage is a very valuable tool for 

 the murrelet biologist, and, given the limitations we discuss, 

 a fairly accurate measure of productivity. Since it is also the 

 only measure we have at present of productivity, we would 

 suggest that investigators take ample data to enable them to 

 evaluate, as we did, the quality of their observations. 



Also, we would suggest that some additional data be 

 taken, such as percentage of molt on the back of the neck 

 (the only area of early molt possible to see if the bird is 



swimming away), the wing shape as pointed versus rounded 

 or "stubby" (see Carter and Stein, this volume), and black 

 versus rusty color on the back. 



Acknowledgments 



We thank Brian Cannon, David Forty, Greg Heidinger, 

 Kimberly Hollinger, Brian O'Donnell, and Jennifer Weeks 

 for their efforts in surveying murrelets. David Forty and 

 John Shaw were instrumental in keeping the two boats running. 

 Brian Cannon helped us evaluate the observations and Robin 

 Wachs helped with analysis. We also thank Jim Baldwin, 

 Ann Buell, George Divoky, Dave Fortna, Deborah Kristan, 

 John Piatt, Dan Roby, Michael Rodway, Steve Speich, and 

 Jennifer Weeks for helpful comments on this manuscript. 



USDA Forest Service Gen. Tech. Rep. PSW-152. 1995. 



377 



