Surveying for Spotted Owls on the east slope of North Cascades National Park Service Complex, 2007-2008

Siegel, Rodney; Jablonski, Kevin; Scholer, Micah; Kuntz, Robert; Wilkerson, Robert

During the 2007 and 2008 breeding seasons, we surveyed transects throughout the Stehekin River watershed and along Lake Chelan, using survey procedures that were virtually identical to those used during the 1990s survey. Over the two field seasons we completed a total of 161 visits (113 visits in 2007 and 48 visits in 2008) to 41 survey transects, and 76 follow-up visits (22 follow-up visits in 2007 and 54 follow-up visits in 2008) to sites with historical detections or new detections gathered during the transect surveys. We found four confirmed Spotted Owl pairs. We also recorded a single detection at one additional site. Of the confirmed pairs, one pair nested and fledged young in both years. A second pair was present but apparently non-breeding in 2007, and then nested and fledged two juveniles in 2008. And, a pair was not detected in 2007, but was found nesting just outside the park boundary in 2008; two juveniles fledged from that nest. Finally, another pair was present but non-breeding in 2007, and then absent in 2008. A pair of Barred Owls nested in 2008 very close to the site of a 2007 Spotted Owl nest. We conclude that the east slope of North Cascades National Park appears to have lost two of its historical Spotted Owl activity sites since the previous extensive Spotted Owl survey in 1993-1996. Both sites were known to be occupied in all four years of the 1990s survey, but repeated, intensive search efforts during the 2007-2008 survey turned up no Spotted Owls, and indeed, found area to be occupied by Barred Owls. Similarly, an activity site, although not known to have been occupied in the early 1990s, was occupied by non-breeding Spotted Owls in 2007, but in 2008 Barred Owls moved into the area and the Spotted Owls could not be found. These results are consistent with other research across the Pacific Northwest indicating that Barred Owls are displacing Spotted Owls across much of their range.

Surveying for Spotted Owls on the east slope of North Cascades National Park Service Complex, 2007-2008

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