Hamady, M., J. Adams, T. Engel, and S. Backe. 2003. Spatially explicit Goshawk surveys on the Kabetogama and Washington/Sturgeon River State Forest. Nongame Wildlife Program, Minnesota Department of Natural Resources Report. 23 pp.
The northern goshawk was surveyed in the Kabetogama State Forest located in Northern St. Louis County and in the George Washington State Forest located in northern Itasca County. The surveys were an effort to expand information on the distribution of goshawk in MN. No goshawk territories were known from the Kabetogama State Forest or the George Washington State Forest. Prior to this survey the location of 50 goshawk nest sites were known as a result of surveys and reporting of accidental discoveries associated largely with past studies. As no overall stratification design had guided the location of surveys, the pattern of goshawk distribution from past surveys cannot reflect the actual distribution of goshawk in Northern Minnesota. These surveys were undertaken mostly to serve the immediate needs of specific studies or local management and had not intended to describe as a whole the distribution of goshawk in MN. Twenty-three territories, for example, are known from the Chippewa Plains subsection as compared to the one known for the Border Lakes subsection. A clustering of territories within and around the Chippewa National Forest is likely a reflection of the location of past study activities. Surveys were also undertaken in parts of the Superior National Forest on the Laurentian Ranger District (four nests in the Toimi Uplands subsection and one in the Laurentian Uplands subsection) and along the North Shore in Lake and Cook Counties (two in the Superior Highlands subsection and one on the borderline between Superior subsection and Border Lakes). Although some effort at surveying goshawk had been undertaken in Voyageur National Park, no goshawk nesting activity was reported. Only one territory was known from extreme North-Central Minnesota (International Falls in the Border Lakes subsection). Surveys in mostly boreal forest landscapes in extreme Northern Minnesota are needed because these landscapes differ the most, along many aspects (management, ecosystems, disturbance regimes, geology), from landscapes where goshawk had been more intensively sampled.
Insight on how forest disturbance regimes, land ownership and logging intensity affect the distribution of goshawk would allow better integration of goshawk conservation into forest management. Surveys are an important tool to management because density differences of goshawk among different management units are a first step to identifying and quantifying factors limiting the species. Because of the large space a single breeding pair of goshawk requires (in the range of 7,000 to 12,000 acres), the spatial scale of different land units that must be compared to assess a difference in goshawk encounter rate would be in the range of tens of thousands of acres. No standardized sampling technique has yet been developed that allows the comparison of goshawk encounter rate among landscapes. Surveys at a spatial scale appropriate to sample goshawk present a challenge because of the large amount of habitat heterogeneity (uplands, lowlands, large number of forest cover types and forest maturity levels) comprised within large land units. In the absence of a standard specifying spatial and temporal survey intensities adequate to determine goshawk occurrence, this survey served as a pilot effort to test the feasibility of quantifying available habitat and rate of survey coverage within a defined survey area. Information on habitat selection by goshawk in Minnesota from recently completed studies was used to identify suitable habitat within the boundaries of survey areas. Details of the sampling methodology used and current limitations to its applicability are discussed.
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Please note that all nest location information has been removed from this document to protect goshawk populations.