O'Donnel) and others 



Chapter 11 



Patterns of Seasonal Variation of Activity 



Cfi LANOMG OR STATIONARY CALUNG 

 CIRCLE BELOW CANOPY 

 H.Y THROUGH CANOPY 

 CIRCLE ABOVE CANOPY 

 FLY ABOVE CANOPY 



(b) 



o 



3 



ABOVE 



BELOW 



17 1S -: 16 17 10 *S 



8 : 8 



A A A 



B *9& * B 



Figure 1 4 (a) Percent of detections of Marbled Murretets in each month for five behaviors at Lost Man Creek, California, 1989- 

 1 991 . The number of total detections in each month is shown above the bars, and the percent of "unknown" behaviors is not 

 shown; (b) Results of Ryan-Einot-Gabriel-Welsh multiple range tests comparing numbers of above and below canopy behaviors 

 by marbled murrelets between months. Months with the same letter indicate that the mean number of detections were not 

 significantly different from each other. The term "n" indicates the number of surveys in the respective month and " x numbers" 

 is the mean number of detections per survey . Means presented are untransformed values. Surveys from all years were combined 

 for the analysis, and months with less than three surveys were not included in the analysis. From O'Donnell 1993. 



volume a). Several studies (Naslund 1993a, Nelson and 

 Hamer, this volume a; Nelson and Peck, in press; O'Donnell 

 1993, Rodway and others 1993b, Singer and others 1991) 

 have also noted the tendency of birds below the canopy to 

 fly silently without vocalizing. The sharp seasonality of 

 below canopy behaviors, in conjunction with these 

 behavioral observations gathered at nest sites, strongly 

 reinforces the relationship between below canopy behaviors 

 and breeding activity. It should be noted, however, that 

 murrelets have on rare occasions been observed flying 

 below the canopy in habitat not considered suitable for 

 nesting (e.g., Habitat Restoration Group 1992; Keitt 1991; 

 Singer and others 1991, 1992). These were usually in areas 

 adjacent to suitable habitat. 



Monitoring 



Current guidelines, as recommended in Ralph and others 

 (1993), restrict surveys for management purposes to the 

 breeding season. The survey season in California begins on 



15 April, in Oregon, Washington, and British Columbia on 1 

 May, and in Alaska on 15 May. The survey season ends on 5 

 August in all regions. The later start of the season at more 

 northerly latitudes reflects a later breeding season in these 

 areas (Kuletz and others 1994c; Hamer and Nelson, this 

 volume a; Sealy 1974, 1975a). The timing of the survey 

 season should of course maximize survey goals. Based on 

 data collected in northwestern California (O'Donnell 1993), 

 the recommended survey season for this state is a reasonable, 

 if not slightly conservative, window for monitoring murrelets. 

 Murrelets were detected during all surveys conducted at 9 

 sites in April (16 of which were conducted before 15 April) 

 throughout the study. Mean detection levels were slightly 

 higher, however, during the last two-thirds of the month. It 

 has been clearly established that numbers of detections, as 

 well as above and below canopy behaviors, usually reach 

 peak levels during July throughout the range of the species. 

 To minimize the likelihood of failing to detect murrelets 

 when they are actually present, Ralph and others (1993) 



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



127 



