Prairies to Peaks:
The Surprising Connection Between Illinois Moths and Grizzly Bears
By Emily Potts
Did you know that the agricultural practices of the Great Plains, especially in Illinois, play a crucial role in the conservation of grizzly bears hundreds of miles away? It’s a fascinating connection uncovered by assistant biology professor Dr. Anant Deshwal and his students.
As a conservation biologist, Deshwal’s research quantifies the combined effect of urbanization and climate change on the community dynamics of birds and insects. Recently, Deshwal received the Council on Undergraduate Research (CUR) Biology Mentor Award for an early career scientist. This award honors biology mentors for their sustained efforts in supervising undergraduate research students.
Last summer, Deshwal and some of his students visited the Nachusa Grasslands near Dixon, Ill., to study different habitat management techniques like prescribed burns, herbivore grazing and invasive weed removal. During their research, they stumbled upon an unexpected moth species: Fall Army Cutworm Moths.
“These moths, usually seen as pests by farmers, are vital for the survival of grizzly bears in the Rocky Mountains,” Deshwal explained. “Though common in the Midwest, they had never been documented in Illinois before. This amazing discovery shows how Illinois could play a key role in conserving grizzly bears in the Rockies.”
To document his findings, Deshwal is teaming up with Wild Excellence Films to develop a 54-minute documentary on this phenomenon called Prairies to Peaks. The film documents the relationship between grizzly bears in Montana and Wyoming and the Army Cutworm Moths from the Midwest. These unassuming moths with a 1 ½-inch
wingspan provide nearly half of the yearly nourishment needed by grizzly bears who consume them within 30 days in the Rocky Mountain West.
The Moths’ Epic Journey
The moths travel 300 miles to feast on the alpine wildflower in Yellowstone and Glacier National Parks and become the richest bear food in the Greater Yellowstone Ecosystem. Some biologists call the moths “bear butter,” due to their high fat content. A grizzly bear may eat more than 40,000 moths in a single day.
Few people realize that these insects migrate from the Great Plains and southern Canada. They consume native prairie plants in places like the Nachusa Grassland and on crops like small grains, alfalfa and canola in agricultural fields, and farmers have been using pesticides to control them, which worries Deshwal.
“The pesticides aren’t 100% effective, so the surviving moths carry these chemicals with them to the Rockies. I’m concerned about how this affects the bears consuming such large quantities daily,” he said. “This could lead to reduced reproduction, poor immune systems or increased mortality.”
Deshwal uses UV powder to track the moths and determine the levels of pesticide and fertilizer accumulation in grizzly bears. His future research will also look into the habitat preferences of these moths, aiming to increase their populations in Illinois while reducing their impact on farming.
“There are many unanswered questions about these moths, but their role in sustaining the western ecosystems is crucial, and I think that’s incredibly cool!”