Crater Lake National Park Biological Sound Station Research: 2014 Annual Report

Ross, Corinne; Mohren, Sean

This report describes the 2014 effort to monitoring spotted and barred owls using acoustic monitoring equipment. Beginning in 1992 the wildlife team at Crater Lake National Park began implementing the USFWS northern spotted owl (Strix occidentalis caurina) monitoring protocol to determine distribution, abundance, and reproductive success of spotted owls in Crater Lake National Park. As the years have progressed, reductions in budgets and increased awareness of safety has reduced our ability to implement this monitoring protocol in its entirety at the Park. In general, the wildlife staff is currently capable of implementing 1-3 noncompliance surveys at each known owl activity center in any given year versus the 6 surveys recommended in the USFWS monitoring protocol. In an effort to help improve our ability to determine the occupancy of an area by spotted or barred owls the wildlife team began exploring the use of acoustic station to help supplement our spotted owl monitoring efforts. In the summer of 2014, fourteen sound stations were deployed at six known spotted owl activity centers and one unsurveyed area that contained spotted owl nesting habitat. The following activity centers were monitored: Bear Bluffs, Bybee Creek, Castle Creek, Grayback Ridge, Sand Ridge, and Sun Creek. All of these activity centers overlapped areas where traditional spotted owl field surveys had been completed in previous years. In addition, one area, North Fork of Copeland Creek, was not a known spotted owl activity center but did contain spotted owl nesting habitat. We deployed two sound stations at each site for a period of 4-16 days. A northern spotted owl was recorded at one site, Grayback Ridge, which was also documented using traditional protocol survey methods. Barred owls were documented at 87% of the sites surveyed and were recorded on 53% of the sound stations deployed. Based on the results of the 2014 effort, we have concluded that acoustic stations can be a valuable tool to help determine spotted owl and barred owl occupancy at known owl activity centers and in new unsurveyed areas of the Park. We plan on continuing this effort in 2015, with the goal of monitoring more known spotted owl activity centers and increasing the number of surveys conducted in unsurveyed areas of the Park to help us better understand the distribution of spotted and barred owls at Crater Lake National Park.

Crater Lake National Park Biological Sound Station Research: 2014 Annual Report

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