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Grosshuesch, D.A. 2006. Western Great Lakes Region owl monitoring survey, 2006 final report. Report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 24 pp.
Executive summary:
As top predators of the food chain, owls are considered good indicators of environmental health, making them important to monitor. However, there is a paucity of abundance and population status data available for most species of owls in the western Great Lakes region. Currently, few species of owls are adequately monitored using traditional avian survey methods, such as the Breeding Bird Survey (BBS) and Christmas Bird Counts (CBC). For these reasons, the Western Great Lakes Region Owl Monitoring survey was initiated in 2005. The objectives of this survey are to: 1) understand the distribution and abundance of owl species in the region, 2) determine trends in the relative abundance of owls in the region, 3) determine if trends are comparable in surrounding areas and analyze whether these trends could be scaled up or down on the landscape, and 4) determine if there are habitat associations of owl species in the region.
This was the second year of a collaborative effort between personnel from the Hawk Ridge Bird Observatory (HRBO), Natural Resources Research Institute (NRRI), MN-Dept. of Nat. Res. (MN-DNR), WI-Dept. of Nat. Res. (WI-DNR), and the Minnesota Ornithologists' Union (MOU) to monitor owl populations in the western Great Lakes region. Existing and new randomly selected survey routes were used to conduct roadside surveys in the Laurentian Forest Province of Minnesota and in Wisconsin. Volunteers were requested to conduct a survey in each period (Period 1-March 11 to March 19; Period 2-March 20 to April 9; Period 3-April 10 to April 23). All survey routes consisted of 10 survey points spaced ~1.6 km (1 mile) apart. A 2 minute "passive" listening period was done at each designated survey point along the route.
The number of routes assigned in 2006 was 138, with 79 in northern Minnesota and 59 in Wisconsin. Of the 138 assigned routes, 69 routes and 52 routes were surveyed in northern Minnesota and in Wisconsin, respectively. At least two surveys were conducted for 88 of the 121 routes completed, with 58 routes being surveyed three times. The number of participants that signed up to conduct an owl survey was 116, with 99 volunteers returning completed survey sheets.
In total, 393 owls of nine species (including 7 owls of an unknown species) were recorded on 83 routes, with no owls recorded on 38 routes (see Table 1). The top three owl species combined for northern Minnesota and Wisconsin were Northern Saw-whet Owl, Barred Owl, and Great Horned Owl, respectively. In Minnesota, a total of 253 individual owls comprising eight species were recorded during all survey periods. The mean number of owls/route was 0.70 for Period 1, 1.82 for Period 2, and 2.08 for Period 3. In Wisconsin, a total of 140 individual owls comprising 5 species were recorded during all survey periods. The mean number of owls/route was 0.96 for Period 1, 1.82 for Period 2, and 1.09 for Period 3.
Recommendations and future perspectives for the Western Great Lakes Region owl survey include: 1) expanding the survey to all of Minnesota, 2) providing on-line training to volunteers, 3) possible integration of an on-line data entry system, 4) conducting analysis of seasonal variation of calling activity, 5) conducting future analysis on abundance trends, habitat associations, and distribution, and 6) considering the importance of using and collecting small mammal data.