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Osprey (Pandion haleaetus)
Ospreys (Pandion haleaetus) were observed on the nest platform on Sylvan Reservoir in
April 2009. However, these ospreys did not stay to raise young.
Owl Surveys
Owl surveys at Camp Ripley began in 1994, and continued annually until 1999. These
surveys were placed on a four-year rotation in 2000, but with the threat of West Nile Virus occurring
in owl populations, the survey is now conducted every year. Data from these surveys is also used to
monitor state and regional owl population trends.
In the past, owls were surveyed at 26 points along one designated route (Route #1) in the
spring to determine presence and abundance of owl species (Figure 29). The survey was conducted
four times during specified survey periods (March 12-March 24, March 25-April 6, April 7-April 19,
April 20-May 2). A three minute passive listening period was used at each point. An additional
survey route (Route #2) was added in 2004, which covers the interior portion of Camp Ripley. This
route was surveyed with similar survey protocol as Route #1.
In 2009, Camp Ripley‟s survey protocol was changed to reflect protocol designed by the
Western Great Lakes region owl monitoring survey (Grosshuesch 2008). This project is a
collaborative effort between Hawk Ridge Bird Observatory, Natural Resources Research Institute,
Minnesota Department of Natural Resources, and Wisconsin Department of Natural Resources. This
survey was developed as a large scale, long-term owl survey to monitor owl populations in the
Western Great Lakes region. It was designed to increase understanding of the distribution and
abundance of owl species in the region since few species of owls are adequately monitored using
traditional avian survey methods such as breeding bird surveys, songbird point counts, or Christmas
Bird Counts. Survey protocol uses existing survey routes to conduct roadside surveys in Minnesota
and Wisconsin. In 2008, the number of survey periods was reduced from three to one period (April 1
to April 15) with a five minute passive listening period. The Western Great Lakes Region survey
analysis of seasonal calling activity data suggested one survey period in April is adequate to detect all
species of interest for monitoring purposes.
In 2009, portions of owl surveys for route #1 were conducted on April 7 (points #6-26), April
8 (point #5), and April 9 (points #1-4). The route #2 survey was conducted on April 8 (points #7-14)
and April 9 (points #1-6). Fewer barred owls (Strix varia) were heard on route #1 this year than from
Page 47
2009 Conservation Program Report