This story appears in the Fall/Winter 2017 issue of 麻豆原创 magazine.
Sustainability is a frequent theme for student research at 麻豆原创, especially in the fields of aquatic and wildlife biology.
Over the past four years, both graduate and undergraduate students have worked with Dr. Brian Hiller, associate professor of biology, to band 1,500 purple martins to help solve the mystery of their declining migration from South America.
Climate change and the insect eaters鈥� reliance on a shrinking supply of human-provided housing are among possible explanations, Hiller said.
Bemidji State maintains two martin houses along its own Lake Bemidji shoreline. Hiller and his students also monitor two martin houses further up the shore at Cameron Park, installed in collaboration with the city of Bemidji and the Minnesota Department of Natural Resources, as well as two others on private lakeshore property and a seventh on Lake Lomond in Bagley.
The effort also includes regional Audubon societies, the Minnesota Ornithological Union and the Mille Lacs Band of Ojibwe.
Biology senior McKenzie Ingram, from Lee’s Summit, Mo., worked with Hiller to band 434 purple martins last summer. Because the martin houses have removable drawers, and the birds don鈥檛 mind being handled, they can be safely banded and returned.
Ingram also monitored the birds from afar. 鈥淚 had this huge spotting scope to read their tiny little bands around their legs,鈥� she said. 鈥淚 would record their age, sex and the band number, and then the weather, and how many birds total, because they don鈥檛 all have bands on.鈥�
Most recently, BSU used simple bands with identifying letters and numbers, but in 2015 Hiller and graduate student Cathy Henry attempted to use GPS to track the martins鈥� migration from Bemidji to the Amazon rainforest. They banded 10 juvenile birds with geolocators, but none returned.
Over two years, Henry checked colonies in Bemidji and Bagley every three days and recorded the martins鈥� band numbers and reproduction. She also used Doppler radar to identify roosts where they gather before heading south. Animated radar data indicated departing flocks.
鈥淚 would go to the area well before sunrise, launch a kayak and paddle around the lake, listening for purple martins calling,鈥� said Henry, who now works as a wildlife technician with the Idaho Department of Fish and Game while preparing to defend her BSU master鈥檚 thesis on martin populations.
Hiller said one theory for the birds鈥� population nosedive in Minnesota is their historic dependence on martin houses, once much more common than they are today.
鈥淭he largest reason is that martins are almost exclusively reliant on people putting up housing for them,鈥� Hiller said. 鈥淭hey switched over from using natural cavities to those that humans provide.鈥�
In addition, the earlier arrival of spring in the Northern Hemisphere because of climate change may put the martins鈥� migration out of sync with their insect food supply.
鈥淚f spring happens earlier, then the bug hatch might happen earlier and it might not coincide with when you have to feed your babies all that protein,鈥� Hiller said. 鈥淚t鈥檚 about that connectivity. The world is connected in ways that sometimes people don鈥檛 think about.鈥�
Written by Bethany Wesley