O'Donnell and others 



Chapter 1 1 



Patterns of Seasonal Variation of Activity 



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Figure 8 Numbers of detections of Marbled Murrelets per survey at three sites on Naked 

 Island in Prince William Sound, Alaska, during the 1991 and 1992 breeding seasons. From 

 Kuletz and others 1994c. 



above the canopy at Lost Man Creek (fig. 14a) are representative 

 of those at the two other sites. Numbers of these behaviors 

 were greatest during the breeding season, reaching a peak in 

 July, and lowest during the non-breeding season, with a small 

 winter peak in November (fig. 14b). 



Below canopy behaviors showed a more pronounced 

 seasonality (fig. 14a) at Lost Man Creek and are representative 

 of the two other sites. Naslund (1993a) found that only a 

 small percentage of detections recorded near two nest trees 

 during the winter, non-breeding season (October through 

 March) consisted of below canopy behaviors (table 1). 

 Similarly, at Lost Man Creek, below canopy behaviors made 

 up 24.7 percent of detections from April through August, 



while from September through March, of 1,185 detections, 

 only five were of murrelets flying below the canopy. Numbers 

 of occupied behaviors were segregated by a multiple range 

 test into three periods at Lost Man Creek (fig. 14b), reflecting 

 peak levels in July, lower levels during the remainder of the 

 breeding season, and their absence in the non-breeding season. 



Vocalizations 



O'Donnell (1993) examined seasonal differences in 

 the number of calls per detection at two sites in northwestern 

 California, Lost Man Creek and James Irvine Trail. 

 Detections with greater then 9 calls were assigned a value 

 of ten for the analysis. The number of calls per detection 



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



