Paton 



Chapter 10 



Defining Detections and Behavior at Inland Sites 



1991; Nelson 1989, 1990a). In most instances, these areas of 

 apparently unsuitable nesting habitat were near or adjacent 

 to potential nesting habitat. Circling is currently believed to 

 be fairly strong evidence that a stand is occupied (Ralph and 

 others 1994). 



(6) Birds seen perching, landing, or attempting to land 

 on tree branches There are a total of six flight behaviors 

 recorded near known active nests (Naslund 1993a; Nelson 

 and Hamer, this volume a; Singer and others 1991). Birds 

 landing in trees could indicate nest sites, although I know of 

 no evidence to suggest that murrelets commonly perch in 

 trees near active nests. Therefore, perching is currently not 

 definitive evidence there is a murrelet nest in the area. 

 During observations of two nests in Big Basin State Park, 

 California, Naslund (1993a) found that, during incubation 

 exchanges, the adults always flew directly to the nest branch 

 without vocalizing (with one exception), landed directly on 

 the nest branch, and then walked to the nest (see also Nelson 

 and Hamer, this volume a). 



(7) Birds calling from a stationary location within the 

 stand. This category only applies to detections with >3 

 calls heard and a bird <100 m away. Adult and juvenile 

 murrelets are generally quiet while on the nest limb (Nelson 

 and Hamer, this volume a). Naslund (1993a) never heard 

 adults give loud vocalizations from the nest while incubating 

 or brooding. Because adults and juveniles tend to be relatively 

 quiet on the nest, this category is probably weak evidence 

 for an active nest in the area, at least for the murrelet giving 

 the vocalizations. Further research is needed to quantify the 

 types of behaviors given at active nests. 



Presence 



When murrelets are detected, but no occupied behaviors 

 are observed, then observation is categorized simply 

 as "presence". 



Discussion 



Most biologists conducting murrelet surveys use 

 detections, defined as the sightings or hearing of individuals 

 or flocks behaving similarly, as the independent sampling 

 unit. The primary variable when comparing studies is the 

 amount of time observers remain at survey stations, which 

 can range from 10 minutes to 3 hours. Most inland surveys 

 conducted to date have concentrated on the breeding season 

 (April through August). However, a recent paper by Naslund 

 (1993b) suggests that surveys during the winter months may 

 be more useful for monitoring long-term population trends. 

 This was because variability in detection rates is relatively 

 low in the winter months compared to breeding season surveys. 

 Currently, we have no basis to convert detection rates into 

 density estimates, and it is unclear when ornithologists will 

 be able to determine an accurate conversion factor. However, 

 Ralph (pers. comm.) and Miller (pers. comm.) recently have 

 been working on determining a conversion factor, using a 

 combination of offshore survey data and intensive inland 

 surveys. Data that have been gathered to date will provide 

 baseline data for future researchers, and can be used for 

 comparative purposes across studies to provide relative indices 

 to murrelet activity patterns. 



Acknowledgments 



I thank Peter Connors, Steve Courtney, Dave Fortna, 

 Anne Harfenist, Gary Kaiser, Brian O'Donnell, C.J. Ralph, 

 Lynn Roberts, Michael Rodway, and Fred Sharpe for useful 

 comments on earlier drafts of this paper. 



116 



USDA Forest Service Gen. Tech. Rep. PS W- 152. 1995. 



