A group of 14 dedicated citizen scientists came together to count butterflies at the Plouff Creek site on Superior National Forest this summer. These citizen scientists are members of the Arrowhead Northern Crescents, a group that monitors butterflies in the region. Members include former Forest Supervisor Jim Sanders and his wife, Pat.

Butterflies have an important role in pollination, crucial to food production, ecosystem health and biodiversity. Superior National Forest wildlife biologists and volunteers annually monitor and collect data on butterfly populations across the national forest. Arrowhead Northern Crescents has partnered with the Forest Service to survey Plouff Creek since 2015.  

The group quickly found its first butterfly, a white admiral, at the creek. They continued across paths on the site, looking for flying or stationary butterflies to count and identify. This type of work requires patience, good binoculars and clear communication to avoid double counting.

One butterfly subspecies that was a particular focus of the count was Nabokov’s blue, which lives only in the western Great Lakes region, is endangered in Wisconsin, threatened in Michigan and a species of concern in Minnesota. On the Hiawatha, Ottawa, Chequamegon-Nicolet and Superior national forests it is listed as a sensitive species.

Nabokov’s blue butterflies are at risk because the larvae only feed on the leaves of dwarf bilberry (Vaccinium caespitosum), which require certain habitat conditions to grow well. Laurie Gawin, Superior National Forest botanist, explained, “While dwarf bilberry plants are not completely shade intolerant, they are “dwarf,” and it does not take much competition to reduce their ability to spread and thrive. Also, like blueberries, they do not normally flower when shaded, thus, reducing their ability to reproduce sexually through seed (fruit) dispersals.”

To enhance habitat for pollinators that don’t live in heavily forested areas, the forest actively uses vegetation management activities like brush clearing and prescribed burning to reduce encroaching shrubs and trees.

“The 10-plus years of working together on the Plouff Creek Nabokov’s blue butterfly survey demonstrates the power gained from partnerships. Together, through population monitoring, we can document the positive results from the habitat treatments the district has completed, demonstrating positive outcomes for the Nabokov’s blue butterfly,” said Jim Sanders.

The group counted 496 butterflies of 12 species in total. Out of five sites surveyed this year, this is one of the higher counts. This data will be sent to the North American Butterfly Association to be archived and used to monitor butterfly populations across North America. A recent study published by the journal Science indicates more than 20% of butterflies have declined between 2000 and 2022. Habitat loss is one reason for this decline.  

As shown in Figure 1, yearly numbers of Nabokov blue have varied significantly, increasing from 124 in 2015 to over 1,550 in 2021. However, an upward pattern of counted Nabokov’s blue is present when looking at the overall trend for this species. Reasons for the apparent trend are hard to determine, but there is hope that with continued management of the site, the numbers of this butterfly will fly higher.

More on threatened, endangered, and sensitive species: https://www.fs.usda.gov/managing-land/natural-resources/threatened-endangered-species.

More on Superior National Forest’s wildlife management program and projects: https://www.fs.usda.gov/r09/superior/animals-plants.

More on the Superior National Forest: https://www.fs.usda.gov/r09/superior.