Chapter 12 



Daily Patterns of Marbled Murrelet Activity at Inland Sites 



Nancy L. NasluncT Brian P. O'Donnell 2 



Abstract: Patterns in the daily activity of Marbled Murrelets 

 (Brachyramphus marmoraius) at inland sites has been studied through- 

 out their range from California to Alaska. Murrelets are most active 

 at inland sites around dawn, and to a lesser degree, at dusk. Throughout 

 their range, peak levels of activity (detections) occur in the hour 

 around dawn, but detections begin progressively earlier as one 

 moves from south to north, corresponding to changing daylight 

 regimes (e.g., California: 45 minutes before to 75 minutes after 

 sunrise: Alaska: 90 minutes before to 40 minutes after sunrise). 

 Timing of dawn detections also varies seasonally in relation to 

 changing sunrise times. The duration of morning activity periods 

 varies seasonally, being longest (2 hours) during summer and short- 

 est 1 hour) in winter. In all areas, weather conditions affect the 

 timing, duration, and level of murrelet activity. In general, activity 

 tends to begin later, last longer, and reach peak levels on cloudy or 

 foggy mornings. The frequency of different behaviors varies through- 

 out the morning period of activity. Murrelets tend to fly below the 

 canopy more before sunrise than after, and group sizes become 

 larger after sunrise. Early detections tend to include more silent 

 birds, solitary calls, and wing sounds than later detections. 



The relatively predictable changes in diurnal activity of 

 birds have been well documented. Patterns of daily activity 

 and behavior can vary widely between species. Knowledge 

 of these activity patterns helps us understand avian ecology, 

 develop appropriate survey techniques, and ultimately to 

 manage threatened or endangered species. Relevant research 

 questions include: How do activity levels and behaviors change 

 between different times of the day? What are reasonable 

 interpretations of temporal variation in behaviors? How should 

 factors influencing variation in daily activity be used to 

 interpret survey results? In this chapter, we examine the daily 

 patterns of Marbled Murrelet (Brachyramphus marmoratus) 

 activity at inland sites and how they are influenced by season, 

 geographic location, and environmental conditions. Where 

 applicable, patterns of subcanopy behaviors (i.e., murrelets 

 occurring below canopy level), thought to be indicative of 

 nesting, are also examined (see Ralph and others 1994). 



Methods and Results 



Data were collected primarily using general and intensive 

 survey techniques (see Paton and others 1990. Ralph and 

 others 1994). During these surveys, each time one or more 

 murrelets were seen or heard, the event was recorded as a 



1 Wildlife Biologist. U.S. Fish and Wildlife Service, U.S. Department 

 of Interior. 101 1 E. Tudor Road, Anchorage. AK 99503 



2 Wildlife Biologist, Pacific Southwest Research Station, USDA Forest 

 Service. Redwood Sciences Laboratory, 1700 Bayview Drive, Arcata. 

 CA 95521 



"detection" (see Paton and others 1990). Additional results 

 from other research activities in murrelet nesting habitat 

 (e.g., nest searches, observations at nests) are presented. For 

 example, data from Alaska are from intensive surveys and 

 from "stake-outs." During the latter, only those murrelet 

 detections that occurred within 100 m of the observer were 

 recorded (see Kuletz and others 1994c, Naslund and Hamer 

 1994). Only visual observations of murrelets were used in 

 analyses of behavior (i.e., flying above or below canopy) and 

 murrelet group size. All detections were used in other analyses. 



General Patterns of Daily Activity 



Murrelets are primarily active at inland sites around 

 dawn and dusk. However, activity levels in the evening are 

 lower and more sporadic than those during the morning. 

 Nelson ( 1 989) recorded that 1 2 percent of detections occurred 

 at dusk and that murrelets were present on only 36 percent of 

 dusk surveys in Oregon during the breeding season. In northern 

 California, dawn activity was about five to six times greater 

 than at dusk (Paton and Ralph 1988). Similar trends have 

 been observed during the breeding season in British Columbia, 

 Alaska, and at known nest sites in central California 

 (Eisenhawer and Reimchen 1990, Kuletz 1991, Manley and 

 others 1992, Naslund 1993a, Rodway and others 1993b). 

 Anecdotal evidence for California and Alaska indicates that 

 dusk activity also occurs during winter but may be less 

 frequent than during the breeding season (Naslund, unpubl. 

 data; Piatt, pers. comm.; Westphal, pers. comm.). 



In central California, two murrelet nests were monitored 

 using video equipment and night viewing devices. Murrelets 

 were not observed visiting nests during the night (i.e., 1 hour 

 after sunset through 1 hour before sunrise; Naslund 1993a). 

 Radar studies on Vancouver Island found no detectable flight 

 activity by murrelets through the middle of the night (Burger 

 1994, Burger and Dechesne 1994). 



Timing and Duration of Morning Activity 



In California and Oregon, murrelets were generally active 

 between 45 minutes before and 75 minutes after official 

 sunrise although most activity occurred during the hour 

 around sunrise (Nelson 1989, Paton and Ralph 1988, Sander 

 1987). Murrelets occasionally were detected prior to 45 

 minutes before sunrise, but rarely more than an hour before 

 (fig. 7; Naslund 1993a, Nelson 1989, Paton and Ralph 1988). 

 Activity in Washington probably began earlier and lasted 

 later than activity further south, and the peak activity period 

 also occurred slightly earlier (Hamer and Cummins 1990, 

 Hamer and others 1991). Murrelets in British Columbia 

 typically became active up to about 75 minutes before sunrise 

 (fig. 1; Manley and others 1992, Rodway and others 1993b). 

 In southeast Alaska, most murrelets were detected between 



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



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