Ralph and Long 



Chapter 35 



Productivity in California-Observations At Sea 



forms a vermiculation pattern, in contrast to the larger blotches 

 of the adult. As the season progresses, the markings on the 

 edges of the feathers are lost, apparently by wear or molt. 

 Another character for identifying young is the egg tooth, 

 which sometimes can be seen into the fall. While this is rarely 

 seen in the field (Carter and Stein, this volume), it has been 

 seen from shore (Strachan, pers. comm.). Finally, fledglings 

 can often be separated from adults by size. When first on the 

 water, young are about 70 percent the size of an adult. 



Methods 



Survey Method 



We conducted productivity surveys in various areas of 

 California during 1993, near Crescent City, Trinidad, Eureka, 

 and Santa Cruz, both at sea and from shore. Surveys began 

 21 June and continued until 1 October. This was the period 

 when young were leaving the nest, continuing until large 

 numbers of adult birds were molting into winter plumage. 



Surveys at sea followed the general survey methods 

 contained in Ralph and others (1990) for offshore surveys. 

 We conducted both intensive and extensive surveys (Ralph 

 and others 1992; Ralph and Miller, this volume), with 

 additional surveys conducted at 200-m intervals from the 

 coastline out to 2000 m. The boat moved as close as possible 

 to each bird seen, giving the observer an opportunity to 

 record data on the plumage and behavior. The time for each 

 observation varied, depending on the ability of the observer 

 to get an adequate view of the bird to assess the plumage, or 

 until the bird left the area. Consideration was also given to 

 minimizing the disturbance to the birds. For example, if a 

 bird was observed to continually dive, apparently to avoid 

 the boat, the observation was terminated. We often found 

 that many of the birds were easily flushed by the boats, 

 making it difficult to get close enough to see identifying 

 criteria such as fine plumage markings and egg tooth of the 

 juveniles. The driver aided in observations when possible. 



Several surveys were conducted from shore using a 40- 

 power spotting scope in a few areas where murrelets occur 

 close to shore, mostly in the Santa Cruz area. Observers scan- 

 ned the ocean from sites located within 50 m of the water's 

 edge and recorded the plumage of each murrelet seen. Data 

 were recorded on all birds seen within 400 m of the observers. 



Data Taken 



The location of the bird was recorded, including the 

 depth of the water and the distance to shore. 



The information recorded for each bird enabled 

 determination of age by both an assessment of the quality of 

 the observation and then by close examination of the plumage 

 information. The quality of the observation was a subjective 

 evaluation of the ability of the observer to see the plumage 

 of the bird, based on the light level and direction, closest 

 distance to the bird, and what feather tracts were seen. We 

 also recorded the length of time over which what we termed 

 the "best view" of the bird was obtained. For example, a bird 



might be in view for several minutes, but the best view 

 might only be the 20 seconds when the observer could see 

 the breast area of the bird while it was facing into the light. 

 The quality of the observation could well be marginal, despite 

 a long view. Specific information used to determine the 

 observation quality was: 



(1) Total time of best viewing. Time for the best view 

 as determined by the information below. 



(2) Light on the bird. Determination if light from the 

 sky was on the front, back, or side of the bird, from the 

 observer's view. 



(3) Light level on the bird. We estimated three 

 categories of light, relatively high, medium, or low levels. 

 A high level would be a sunny day, while a medium 

 level would be high overcast or bright fog. Low levels 

 would include a dense, low overcast, very dense fog, or 

 just at dawn or dusk. 



(4) View of bird, as to either the front, side, and/or back. 



(5) Distance to bird at the best view. 



A description of the bird and its plumage was recorded 

 for the entire observation, and was not limited to information 

 gained from the time of best view. The description of the 

 bird included: 



(1) Bill details. Bill color, and presence or absence of 

 an egg tooth. 



(2) Size of bird. As compared to others in the group. 



(3) Type of plumage. The feather tracts of principal 

 concern were the breast, belly, and sides. We recorded 

 the percent area of dark color, seen as dark blotches or 

 fine markings, versus the area that was white. The total 

 for a feather tract would always be 100 percent. If birds 

 stretched their wings, we noted any missing flight feathers. 



Behavior was also recorded to evaluate the possibility 

 of juvenile behavior, with an indication of numbers of birds 

 involved in a group. Behaviors recorded were position of 

 birds in a group, begging, feeding of another bird, and 

 vocalizations. Other information, such as condition of 

 primaries, was included as notes. 



Evaluation of Productivity Data 



We separated observations into five categories to designate 

 the age of the birds as: definite adult, probable adult, unknown, 

 probable juvenile, and definite juvenile. In determining the 

 category, we subjectively considered the quality of the 

 observation from data given by the observer during the best 

 view of the bird, as described above, to determine if the bird 

 should be rated as a definite, probable, or unknown plumage. 

 For example, the bird was assigned to the category of 'probable' 

 if the observation was of poor quality due to low light levels, 

 distance, or view. The combination of length of best view 

 and light levels was a critical factor. We felt that at least 15 

 seconds were required for a good quality observation under 

 good light conditions, longer if the lighting was poor (e.g., 

 low levels or back-lighting). Distance to the bird was also a 



372 



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



