Surveying for spotted owls in the Upper Skagit watershed of North Cascades National Park Complex, 2009-2010.

Siegel, Rodney; Kuntz II, Robert; Wilkerson, Robert; Kuhlman, Kara; Toshack, Michelle

Northern Spotted Owl populations have declined over the last century, and the subspecies has been federally listed as “threatened” since 1990. Northern Spotted Owl status has not been well documented in the North Cascades of Washington and southwestern British Columbia. In 1993, National Park Service resource management staff initiated the first comprehensive inventory of Spotted Owls in suitable habitat within North Cascades National Park Complex (NOCA), a 4-year survey that identified 11 active Spotted Owl territories. During the 10 years following completion of NOCA’s 4-year baseline owl inventory in 1996, only sporadic compliance-related owl surveys occurred. Comprehensive, up-to-date information on the park’s Spotted Owl population was needed to aid updating NOCA’s Fire Management Plan, General Management Plans for Lake Chelan and Ross Lake National Recreation Areas, and developing the Stehekin River Corridor Implementation Plan. Thus, NPS partnered with The Institute for Bird Populations to initiate a multi-year study of the status of NOCA’s Spotted Owl population. The project has three main objectives: 1. Revise NOCA’s model of suitable habitat for Spotted Owl and develop a GIS map layer showing suitable Spotted Owl habitat throughout the park. 2. Resurvey transects that were established and surveyed from 1993-1996; locate active Spotted Owl territories, estimate relative abundance, and determine productivity at all activity sites found. 3. Develop individual Spotted Owl activity site management plans with recommendations for protection measures for both currently active and historic sites. During the project's first year, we revised NOCA’s model of suitable Spotted Owl habitat, in completion of Objective 1. During 2007 and 2008 we conducted fieldwork throughout the Stehekin River watershed and along Lake Chelan within LACH, in completion of Objective 2 for the part of NOCA east of the Cascades crest. We also began drafting Spotted Owl management plans for currently active and historic Spotted Owl activity sites throughout the part of NOCA that we surveyed in 2007-2008. In 2009 we began a 2-year effort to complete Objective 2 for the northeastern portion of NOCA, including the Newhalem Creek, Panther Creek, Ross Lake, Big Beaver Creek, Little Beaver Creek, Ruby Creek, and Thunder Creek drainages – referred to collectively here as the Upper Skagit Watershed. This report details the final results from our 2009 and 2010 field seasons. We surveyed transects throughout the five drainages using survey procedures that were identical to those used during the 1990s survey as well as during our 2007-2008 surveys. During 2009-2010 we completed 141 surveys (75 in 2009 and 66 in 2010) of 74 transects (38 in 2009 and 36 in 2010), comprising 2,363 2-min or 10-min station surveys plus 41 follow-up visits to historic Spotted Owls activity sites (13 visits in 2009 and 28 visits in 2010). None of our transect surveys during the 2009 or 2010 field season yielded Spotted Owl detections, but our follow-up visits to sites with historical detections confirmed at least one resident Spotted Owl occupying the historical territory at Newhalem Creek. Additionally, an incidental detection of one Spotted Owl was recorded near Pyramid Lake by an NPS Ranger during the 2010 field season. Our survey efforts suggest that historically occupied territories at Deer Lick, Little Devil/Stout Creek, and Big Beaver Boundary are no longer occupied. We also documented all other owl species detections. We observed and documented individuals of 5 additional owl species: Great Horned Owl, Barred Owl, Western Screech-Owl, Northern Pygmy-Owl, and Northern Saw-whet Owl. The large number of Barred Owls detected indicates a substantial population increase since the early 1990s; population growth in this species may be displacing Spotted Owls.

Surveying for spotted owls in the Upper Skagit watershed of North Cascades National Park Complex, 2009-2010.

Series

Collections