Connecticut Warbler and other songbird populations on the decline in Superior National Forest
For nearly 30 years, researchers at the Natural Resources Research Institute (NRRI) have conducted annual surveys of songbirds in the Superior National Forest and Chippewa National Forest in northeastern Minnesota.
“The Superior National Forest, in particular, has some of the highest breeding bird diversity in North America,” Steve Kolbe, an avian ecologist with NRRI at the University of Minnesota-Duluth, said.
The Superior National Forest provides habitat for 163 species of breeding birds, according to the Audubon Society.
Researchers take to the woods every summer to collect data for the Minnesota National Forest Breeding Bird Monitoring Program, which started in 1995. The data collected provides insight into the impacts of management policies and conservation initiatives.
“The information is extremely valuable,” Kolbe said. “It helps guide us to species or groups of species that might need further investigation or might be sort of warning us of things that are happening in the environment.”
Kolbe said there was a lot of foresight in the mid-1990s to start the program. “The way it was set up was we have 1000 GPS point counts that we go to every year,” he said. “You walk out to the point, and you stand there for ten minutes and write down every bird you see. But mostly, you write down every bird that you hear.”
Throughout the 30-year program, researchers have discovered the decline of particular species, such as the Connecticut Warbler and the Canada Jay, also known as Whiskey Jacks, in both National Forests.
Kolbe said in the mid-1990s, researchers frequently documented 30 to 40 Connecticut Warblers each year. However, he said, “In the last few years, we’ve had zero.”
“So they’re sort of becoming extirpated in the Superior National Forest and almost in the Chippewa as well,” he added. “So that’s alarming.”
The Connecticut Warbler thrives in black spruce and tamarack bogs. Kolbe said a handful of reasons contribute to this particular habitat’s loss. A few reasons include the harvesting of black spruce through logging and forest management practices and the expansion of the Eastern larch beetle, a native forest pest destroying tamarack across the state.
“Also, Connecticut Warblers are long-distance migrants that may experience a number of dangers along their migratory route in the spring and fall,” Kolbe said.
Other species on the decline within the Superior National Forest are aerial insectivores, birds that rely exclusively on flying insects for their diet. Species such as the Nighthawk, Swifthawk, and Swallows.
“So there’s been a lot of talk in recent years about long-term and potentially alarming declines in insect abundance globally,” Kolbe said.
In addition, Kolbe said the decline of the Connecticut Warbler and other species in the National Forests is an indication of climate change. Northeastern Minnesota consists of boreal forests containing conifers, such as spruce, fir, and pine. The conifer forests are ideal habitats for many bird species. However, Kolbe said that conifer forests are migrating further north due to climate change, and deciduous forests are taking their place.
While Kolbe anticipates that species that prefer conifer forests will continue to decline, he said the encroachment of deciduous forests would bring an increase in new bird species. “So that’s a sign of the future here now,” he said.
“So birds like Wood Thrushes, or Black and White Warblers, or even Black-Throated Blue Warblers are increasing significantly in the Superior National Forest,” Kolbe said. “And it’s because we’re seeing more and more deciduous trees popping up in the understory and the overstory.”
Outdoor News Podcast host Kalli Hawkins speaks with Steve Kolbe, an avian ecologist with the Natural Resources Research Institute at the University of Minnesota – Duluth, about the songbird population trends in the 2022 bird monitoring program annual report. Audio from the interview is below.