Impacts on Changing Monarch Populations

Shown is a dataset of monarch sightings between the years of 2017 and 2021 at Indian Creek Nature Center. Since 2021 there have been fewer monarch sightings.

Indian Creek Nature Center sits on over 210 acres of land that consists of forests, wetlands and prairies in Linn County, Iowa. It contains restored prairies that are full of milkweed and other flowering plants. Researchers at Iowa State University have found that monarchs need large stretches of land containing milkweed, which makes Indian Creek Nature Center an ideal place for this keystone species. In addition, Iowa State University’s Iowa Monarch Conservation Consortium has noted an increase in milkweed populations in Linn County due to conservation efforts. Due to the changes in milkweed populations in Linn County there was a rise of monarch populations spotted at Indian Creek Nature Center up through 2021.

On August 10, 2020 a derecho devastated Indian Creek Nature Center causing a loss of 60% of the trees on the property. Cleaning up from the derecho took nearly three years (between 2020 and 2023). Indian Creek has replanted around 100 trees in the wetland areas and continues to restore the forest habitats in the area. In 2023, construction started on the relocation of a local historic bridge called Blue Bridge, to the Indian Creek property. The bridge was installed in the area of Indian Creek where the survey is taken each year. The nature center saw a decrease in butterflies in the seasons following these events with lowest numbers observed in 2024.

Over the years, the nature center’s butterfly survey has lined up with the Monarch Festival, during which Indian Creek Nature Center partners with the Monarch Research Project to release monarch butterflies. It occurs in mid-July each year, which corresponds to a spike in monarchs spotted in the following weeks.

Indian Creek Nature Center land management efforts also include regularly scheduled prairie burns to clear out invasive species. In 2024, the majority of the butterflies observed were in the sections of prairie that were burned within the past year. Occasional spot planting of specific species includes host plants for butterflies, such as milkweed for monarchs.

• What has been causing the changes in the monarch population at Indian Creek since 2017?

• How has the monarch population changed at Indian Creek Nature Center?
• Why did monarch populations rise and then suddenly fall in 2022 at Indian Creek Nature Center?
• What is happening to the monarch population across the United States?
• How does this compare to Indian Creek Nature Center’s monarch population?
• What resources do monarchs need to survive?
• How have land management practices changed over time?
• How do land management practices affect monarch populations?
• What is the most effective strategy to increase monarch populations?
• Why are monarchs and other pollinators important to Iowa?

Students could:

• Research how changes to the land impact the population of monarch butterflies. Students could explore how changes at Indian Creek Nature Center have affected monarch populations.
• Have students compare these events at Indian Creek Nature Center with the changes in the monarch populations. Key events include the 2020 derecho and the construction for the moving of a historic bridge to the Indian Creek Nature Center property.
• Research how humans are changing monarch habitats and how that affects the monarch population. Research the effect of commercial agriculture on monarch populations including the impact of pesticides and herbicides on milkweed. Use data such as the World Wildlife Fund Data to explore deforestation in Mexico at the monarch’s wintering grounds.
• Research the impact of restoration efforts on monarch populations in Iowa. Looking at the Iowa State University milkweed data reveals that there has been an increase in milkweed across the state since 2015. In addition to this, research how milkweed should be planted.
• Research different methods for helping restore pollinator populations across the state, compare the different methods and identify which they think is the most effective method. Using this information students could put together an infographic, poster or presentation to educate the public about why it is important to help pollinators and what actions they can take. Other actions that could be taken is to have students create a land management plan for their school presenting ways to use school grounds to increase monarch and other pollinator populations.

• Indian Creek Nature Center | The Sunny Side of the Derecho: Ecological Advantages: This article describes the ecological advantages of the 2020 derecho at Indian Creek Nature Center.
• Indian Creek Nature Center | Survey Data: This teacher-created resource shows the Indian Creek Nature Center butterfly data for monarch and other butterfly species.
• Iowa Monarch Conservation Consortium | Yearly Trends in Monarch Habitat Acres and Milkweed Stems: This site shows the changes in milkweed populations across Iowa.
• Iowa Monarch Conservation Consortium | Tracking Monarch Butterflies: This explains how Iowa State University researchers have tracked the movement of monarch butterflies.
• Iowa Monarch Conservation Consortium | Tracking Monarch Butterfly Movements: Tracking monarch butterfly movements
• Iowa Public Radio | River to River: Unraveling Data From the 2020 Derecho, an Update on the Waning Monarch Butterfly Population: An episode of Iowa Public Radio’s River to River program discussing the 2020 derecho with a geological and atmospheric scientist from ISU (00:00-14:00 minutes) and an entomologist describing milkweed populations and their effects on Butterflies. (14:00-23:00 minutes)