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The Common Tern is a key focal species for the Midwest Coastal Program, reflecting its vital role in the Great Lakes ecosystem. In 2024, the Coastal Program conducted productivity monitoring at two important nest sites: Ashland Tern Island in Chequamegon Bay, near Ashland, WI, and Interstate Island in the St. Louis River, situated between Superior, WI and Duluth, MN. This monitoring also assessed the success of vegetation planting initiatives led by the Minnesota Land Trust. Currently, only two nesting areas for common terns remain in the Lake Superior watershed, both in Western Lake Superior. The decline in breeding pairs and their distribution across the Great Lakes has raised the Common Tern's status to a "Bird of Conservation Concern."
Interstate Island was established in 1934 by the United States Army Corps of Engineers as a dredge material disposal site, however, high water levels since 2015 have reduced the island鈥檚 size from five acres to just 2.5 acres, threatening its nesting habitat. Between 2020-2023, the Coastal Program supported a project to expand the size of the island to 8.7 acres. In contrast, Ashland Tern Island, which can support 200 nesting pairs, has been a successful tern nesting habitat since 1974 making it the oldest Common Tern colony on Lake Superior. The Wisconsin Department of Natural Resources recognizes Ashland Tern Island as the most important tern colony in the Great Lakes due to its historical significance and ongoing success in supporting healthy tern populations. The Coastal Program鈥檚 contributions to habitat restoration are increasing the nesting success of the tern colonies at both islands.
A Coastal Program biologist participated in productivity monitoring during the breeding season, from mid-May to early August. Each island is visited every five days to evaluate nesting success and document any predation events. This careful monitoring is essential for quickly identifying and responding to potential threats to the populations. During the 2024 nesting season, Ashland Tern Island recorded a peak nest count of 140, with 307 chicks banded and 185 successfully fledging. This translates to a productivity ratio of 1.32 chicks per nest. Predation, particularly by Peregrine Falcons, was the leading cause of chick loss at Ashland Tern Island.
Interstate Island achieved even better results, reporting a peak of 118 nests with 275 chicks banded and a record 240 chicks fledged. This remarkable productivity rate of 2.03 chicks per nest is the highest ever recorded at this site. The success of Interstate Island can be attributed to the use of fencing and other structures to exclude predators from tern nests, including peregrine falcons and ring-billed gulls. Controlling predator populations has also been an effective strategy to increase nesting success.
Monitors are also using game cameras to document predation incidents, providing valuable data for ongoing evaluations. This comprehensive approach to wildlife management exemplifies the collaborative efforts of various stakeholders committed to conserving the common tern throughout the Great Lakes region.
