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Martell, M., J. Nibe, and J. Galli. 1990. A report on bald eagle use of the Wacouta Bay, (Mn.) area of the Mississippi River along with management recommendations. Final report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 15 pp.
Introduction:
Bald eagles (Haliaeetus leucocephalus) use the Mississippi River as a nesting, migration, and wintering area. The importance of this area to wintering eagles has been recognized for many years, and probably began with the construction of Locks and Dams along the river earlier in this century. Currently the Mississippi River and its tributaries account for more than 30% of the Bald Eagles wintering in the lower 48 states.
We began a 3 year project to document bald eagle use of those portions of the Mississippi and St. Croix Rivers bordering the State of Minnesota in the winter of 1987-88. Total counts of eagles using the rivers were made during weekly aerial flights. Feeding areas, daytime perching spots, evening roosts,and travel areas along the river were monitored from the ground. In addition, individual eagles were tracked with radio telemetry.
In November of 1989 an evening roost was discovered at Wacouta Bay, south of Red Wing, on the Minnesota side of the river. Bald eagles using the roost were counted once a week beginning 22 November and ending 6 April 1990. Observers with spotting scopes counted all eagles using the roost, and attempted to determine the birds age; either adult (mostly white head and tail) or subadult. Failing light often made this distinction difficult. Counts were taken starting at 1600 hrs. and continued until dark.
Aerial surveys were conducted weekly to bimonthly from October through March in 1987, 1988, and 1989 including January through March 1990. Counts were conducted by two observers (the pilot and a biologist) usually in a Cessna 172 at a survey height of 150-300 feet above ground level. The survey route along the Red Wing portion of the river followed the mid-line of the main river channel from Lock and Dam #3 south or east to river mile (RM) 788. The route turned north and eagles were counted along Wisconsin channel west to its confluence with the main channel at RM 793.4. The plane then returned to the main channel and counts resumed at RM 788.
The route did not pass directly over the roost. Perched eagles were counted along both sides of the main channel and the shore of Upper and Lower Lakes. Notes were also made of flying eagles. The plane usually did not disturb the perched birds.