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Western Great Lakes Gray Wolf
Phone: 612-713-5360 |
Common Terns
The two major threats to common terns on Hennepin Island, are competition for nesting sites with ring-billed gulls and weather.
A project to increase common tern production at Mille Lacs NWR was initiated in 1993 with the assistance of Mille Lacs Band of Ojibwe DNR biologists. The project includes installing a gull exclosure (deterrent) grid over the gravel beach potion of Hennepin Island during the nesting season.
The grid acts as a barrier to ring-billed gulls which compete for nest sites with terns, but the grid lines are spaced to allow terns access to the beach.
Since most of the common terns (>95%) on Mille Lacs NWR nest on Hennepin Island, no management efforts to enhance the common terns on Spirit Island have been conducted.
Weekly trips are made to Hennepin Island during the breeding season to monitor the breeding success of the common terns. Nests are established in mid-May.
Heavy winds and wave action destroy a few of the tern nests on the spit that are not protected, however many of the terns initiated second nests on slightly higher ground and under the grid system.
The nesting colony of common terns on Hennepin Island produced 200 fledglings in 2000, which constituted the highest number of fledglings produced since the project was initiated. In 2003, 51 common terns fledged from the island.
