Sherburne National Wildlife Refuge (Refuge) is located in east-central Minnesota, less than an hour?s drive from the northern suburbs of the Twin Cities of Minneapolis and St. Paul (see map). It is about 65 miles from the Twin Cities International Airport via Interstate 94 and U.S. Highways 10 and 169. A network of county roads border and bisect the Refuge, giving ready access to visitors. St. Cloud, the State?s third largest city outside of the Twin Cities metropolitan area, is about 20 miles to the west. Elk River, Zimmerman, and Princeton are other smaller municipalities in close proximity. It is situated in one of the fastest growing counties in the state.
The Refuge lies on a sandy glacial outwash known as the Anoka Sand Plain. The area is also within what was the transition zone between the prairies to the west and the forested regions of the eastern part of the continent. The advance and retreat of the grasses of the prairie ?sea?, along the woodland ?shore? was largely a function of fire, both natural (lightening) and human caused. Vegetation communities present on the Refuge prior to settlement by Europeans were largely adapted to periodic fire. The uplands were dominated by oak savanna; a habitat type characterized by scattered individual and/or clumps of oak trees with a prairie understory. Historically, the oak species in this community type where the Refuge is located were pin and bur oaks. Once the dominant plant community in the Upper Midwest, now less than 0.02 percent remains. A small area of the Refuge north of the St. Francis River was the lone representative of a woodland in central Minnesota known as the ?big woods?; a maple-basswood hardwood forest type no longer intact on the Refuge.
Upland management focuses on the restoration of the historical vegetative communities. The Refuge is actively restoring their uplands to those native habitats that existed prior to European settlement. The majority of the large open fields that were formerly cropfields have been planted to native grasses and forbs, creating the understory for the eventual conversion to oak savanna. Prescribed fire is applied extensively to facilitate this process ? invigorating the native grasses and opening the canopy of overgrown hardwood stands. Restoration efforts for the big woods consists of allowing forest succession, some planting of native species and reduction of invasive species.
Wetlands comprise about half of the Refuge?s 30,700 acres. The St. Francis River, a small stream, enters the Refuge in the northwest and flows generally east and then turns south to exit the Refuge on its southeast end. This river, its floodplain and associated wetlands form the backbone of the Refuge. Two large man-made impoundments and Rice Lake are located along the main stem of the river. The latter is one of four natural lakes that exist on the Refuge. Emergent wetlands were scattered throughout the Refuge prior to European settlement. Many of these were drained through the construction of an extensive ditch system in the early 1900?s. Several have been restored to form a series of 23 interconnected wetland impoundments on the Refuge, fed by the St. Francis River. Wetland management focuses on manipulation of water levels in the impoundments to produce habitat conditions to favor a diversity of water birds and migration habitat for waterfowl. Tamarack swamp, a forested wetland habitat type that was more plentiful before European settlement of the area, is now rare on the Refuge.
In the center of the Refuge, Blue Hill rises to an elevation of 1090 feet MSL, one of the highest points in Sherburne County. This is a rise of about 100 feet above the surrounding landscape. The remainder of the Refuge is relatively level, ranging from 950? MSL to 990? MSL. This flat landscape is marked by wetland depressions and the fairly narrow channel and floodplain of the St. Francis River.
The mix of marsh, oak woodlands, open native grasslands, oak savanna, lakes and the river habitats attracts a wide variety of birds.
Visitor facilities for viewing birds are comprised of a 7.3 mile automobile tour route, the Mahnomen and Blue Hill hiking trails. The hiking trails are open year around, turning into cross-country ski trails in the winter. The tour route is closed during the winter and does not open in the spring until after the bald eagle pair that have nested along it since 1983 have hatched their young (usually around mid-April). The tour route also has three short walking paths through the Refuge?s main upland habitat types, oak savanna, woodland, and prairie. Additionally, several county roads border and bisect the Refuge, offering more viewing opportunity throughout the year.
Sherburne County boasts 301 species 94 of which are considered breeders (see MOU County Checklist attached). The Refuge Species List (attached) as well as the MOU?s Sherburne County List document the wide diversity of birds that utilize Sherburne NWR as both a migratory and breeding area. Over 230 bird species have been recorded on the Refuge. Of these, 124 have been confirmed as breeding. Data from a non-random Breeding Bird Survey Route performed since 1990 documents more than 130 different species records over the past 16 years (1990-2005), with an annual average of 78 and the most recent five year annual average of 81 (see attached summary). A Christmas Bird Count, centered on the Refuge, has been conducted from 1970 to present, with the exception of 1985. This survey has recorded up to 40 bird species, with an overall average of 27, and a 5-year average of 37 from 2000-2005 (see attached CBC summary). Rare species also frequent the refuge. For example, just within the past two years MOU members and Refuge staff have documented Least Tern, Yellow-breasted Chat, Summer Tanager, Little Blue Heron, Hooded Warbler, Short-eared Owl, and Acadian Flycatcher. Sherburne NWR regularly supports breeding populations of the following state and/or federally listed species of concern: Bald Eagle (State Special Concern) and Trumpeter Swan (State Threatened). Since 1985, when the first breeding eagles were confirmed, the number of active eagle nests on the Refuge has grown to eight (see attached table). Over the 12 years from 1985 through 2006, 124 birds have been fledged.
Trumpeter Swans have been regularly using the Refuge since the 1980?s. The first pair to successfully nest and raise young included a marked female. They raised 5 young to fledging in 1997. This pair did not return to the Refuge to nest again due to the death of the female during the winter of 1997/98. In 2004, two unmarked pairs nested on the Refuge for the first time since the 1997 pair. Each pair hatched five young. One pair fledged all five cygnets, the other fledged none. In 2005 three pair nested on the Refuge and fledged 5, 5, and 2.
The Refuge also regularly supports minor numbers (i.e., less than 10) of breeding Henslow?s Sparrows (State Endangered), Hooded Warblers (State Special Concern), and Red-shouldered Hawks (State Special Concern). A single singing male Yellow Rail (State Special Concern) was recorded for the first time on the Refuge during a marshbird survey in 2005. However, it was not observed again in 2006.
Non-breeding American White Pelicans (State Special Concern) utilize Refuge wetlands as a stopover during spring migration and as a feeding area during the late summer months (mid-July to September), with peak daily highs of 300-400 birds across the Refuge. Peregrine Falcons (State Threatened) nesting at the Excel Energy power plants in Monticello and Becker, both within 15 miles of the Refuge, commonly use the Refuge to feed. Forster?s Terns (State Special Concern) regularly use the Refuge in migration, and Loggerhead Shrike (State Threatened) are occasionally observed in the winter on the Refuge. Long-term bird monitoring surveys performed on the Refuge include: Waterfowl and Waterbird (weekly during spring and fall migration since 1981, records dating back to 1970), Secretive Marshbird (three times a year following National Protocol since 1999), Breeding Bird Survey non-random route (annually since 1990), Greater Sandhill Crane Unison Call Count (annually since 1981), Bald Eagle Breeding and Productivity Surveys (since 1985), Landbird Point Counts (2 consecutive years repeated every five years since 1994), Christmas Bird Count (annually since 1970), North American Migration Count (annually since 2004).
In addition to these long-term bird monitoring surveys, Sherburne NWR regularly serves as study area for bird-related research. The following is a sampling of work performed on the Refuge in the past ten years:
Independent Undergraduate Projects
Various students from Bethel University, St. Cloud State University, and the University of Minnesota on a variety of bird-related topics including Greater Sandhill Crane nesting, Black Tern nest site selection and productivity, field trial for standardization of marshbird protocol, Bald Eagle nesting and disturbance, and the response of wetland birds to drawdowns.
Reduction of Land Management:
Due to the urbanization surrounding the Refuge, some land management activities are becoming increasingly complex and more difficult to apply. This essentially reduces the area the Refuge is able to effectively manage for wildlife. A prime example is prescribed burning which is critical to the restoration and maintenance the Refuge?s major upland habitat target of oak savanna. As the proximity and density of dwellings adjacent to the Refuge boundaries continues to increase, the liability of such management actions also increases, as does the concern over smoke management. These factors increase the complexity; and therefore, the staffing and contingency resources required to apply the management action.
The Refuge continues to work to educate surrounding communities and neighbors, as well as Refuge visitors, about the wildlife conservation mission of the Refuge, management actions needed to implement this mission, the process and effects of management actions, and the value of the Refuge and wildlife conservation to the human communities and residents of the area.