CEDAR RAPIDS — In a dense patch of prairie at Indian Creek Nature Center one recent summer morning, Cornell College sophomore Emmaline Fievet and Xavier High School senior Madeline Murphy were carefully documenting milkweed plants, hoping to learn a little more about the monarch butterflies that depend on them.
The students were working with Tammy Middlestein, an assistant professor of biology at Cornell in Mount Vernon. She specializes in conservation and the biology of endangered species, and much of her time is devoted to a very different species than monarchs; she studies flying foxes in Southeast Asia, where she travels about four times a year.
She said, on the surface, studying monarchs is not all that different.
“They have the same challenges of habitat and population loss,” she said. “We have to figure out how to track that.”
It’s an urgent topic. Since the 1980s, the population of monarchs overwintering in California has experienced a 99.4% decline, according to the conservation organization the Xerces Society, and the population that overwinters in Mexico has declined more than 80 percent.
Monarch caterpillars only eat milkweed, so restabilishing the plant across the region is vital. The question Middlestein and her students are trying to answer is how much milkweed and prairie it will take to make a difference.
“We’re trying to understand how much prairie we need across North America to bring the population up,” Middlestein said. “It’s about understanding how many milkweed are in a typical prairie and how many monarchs does that produce ... There’s an international push to create more prairie habitat for monarchs, but nobody has a sense of how much we need to plant.”
Students key to research effort
Murphy connected with Middlestein through Kirkwood Community College’s Workplace Learning Connection, which aims to help high school students explore possible careers through internships, job shadows and more. Fievet, who is a premed student studying biochemistry and molecular biology, is working with Middlestein through the Cornell Summer Research Institute.
“It’s been cool getting to collect data that’s doing something, and feeling like you’re doing something in the real world,” Fievet said.
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At the beginning of the summer, they picked several prairie locations and did density counts for common milkweed, choosing areas with high density to follow throughout the summer. Throughout the summer, the students have returned to those spots every couple of days, painstakingly documenting what they find. They go out five days a week for eight week, rotating between different prairies.
At each prairie, they measure the height of each milkweed plant, count how many leave it has, and look for any monarch eggs and caterpillars, tracking their survival rates over time. Even if they don’t see caterpillars, they can spot evidence of them by looking for crescent shaped holes that newly hatched monarch caterpillars chew in milkweed leaves.
Survival is an uphill battle for the butterflies even with milkweed, with the eggs and caterpillars subject to predation and other factors. Middlestein said only 5 to 10% of eggs that are laid actually hatch, and of those caterpillars a small percentage make it to become butterflies. The caterpillars ingest toxins when eating milkweed, which protect them from most predators as butterflies, but monarch butterflies face challenges of their own, including climate change and pesticides sprayed on lawns and commercial farms alike, as well as finding enough nectar to sustain themselves on their migration journeys.
The research Middlestein and her student do will be shared with other organizations doing similar work across Iowa, including the DNR.
Middlestein started this research five years ago and plans to continue for the foreseeable future. In addition to the benefit for monarch restoration work, she said the project is a good, hands on way for students to get started in scientific research.
“It’s a nice way to get students out into native Iowa habitat and learning about what’s local. It’s nice place-based learning,” she said.
It also yields large amount of raw data the students can then use to study different questions. She has had students take the data and examine things like how mowing and burning impacts monarchs. Both are prairie management techniques that humans use to mimic how native prairies previously functioned. Mowing once a season replaces the grazing of bison that are no longer part of Iowa’s prairies, and burning clears out old growth and non-native species.
Middlestein said some of the research findings have surprised her. She said conventional wisdom was mowing in midsummer was detrimental for monarchs because it would kill caterpillars and eggs. However, one of her students found the milkweed that grew back up after mowing supported more monarchs than the old plants did, showing that rather than hurting them, midseason mowing had a net benefit for the species.
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Middlestein said they’re still trying to determine why that may be — it could be related to the height of the plants, the amount of sap in new plants versus old plants, or some other factor they haven’t considered. She said this kind of information can help people managing prairies make important decisions.
Murphy said it’s been eye-opening, learning about the prairie and how many elements work together to help even just one species survive.
“It’s really interesting to be able to step away from everyday life and appreciate the nature around us,” Murphy said. “Many people just pass the fields every day and don’t really think about what’s going on there.”
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