Tammy Mildenstein, Cornell College – Monarch Butterfly Preservation

On Cornell College Week: The restoration of monarch butterfly populations is a vital preservation topic.

Tammy Mildenstein, assistant professor of biology, says how we still need to know more about how they use their habitat.

Tammy Mildenstein is an assistant professor of biology at Cornell College in Mount Vernon, Iowa. She teaches courses in biology, including Ecology, Environmental Biology, Conservation Biology, and Organismal Biology. Tammy studies threatened flying foxes in Southeast Asia and Oceania. Most recently, she has taken students to Myanmar to study flying fox conservation. Her local research with students focuses on monarch butterfly conservation and involves prairie restoration projects. Mildenstein has a Ph.D. in Wildlife Biology from the University of Montana, Missoula.

Monarch Butterfly Preservation

Monarch butterflies are the most widely recognized butterfly in North America.

Recently, monarchs have gained attention as a species of conservation concern. With over 90% population declines over the past two decades, they are now being considered for protection under the United States’ Endangered Species Act. Multiple factors like habitat loss, disease, predation, climate change, and pesticides, contribute to their endangerment, but it is the loss of tallgrass prairies that is considered a conservation priority. From backyard butterfly gardens to multi-million dollar prairie restoration campaigns, America is racing to restore native milkweeds: the only plants used by monarchs to raise their caterpillars.

Unfortunately, we lack details about how tallgrass prairies, milkweeds, and monarchs are related that would help us better provide habitat. Each summer, my team of undergraduate students visits hundreds of milkweed plants looking carefully under each leaf to record the presence of eggs and caterpillars. These data help us understand how many monarchs a tallgrass prairie typically produces.

We have learned a lot that might support the restoration of monarch populations. Although milkweed densities in prairies number up to 1000/hectare, only a small fraction of milkweeds are ever used for egg-laying. Monarchs choose the younger plants, putting their eggs in the tops of the plants, likely because this is the easiest part of the plant to access. We have also learned that less than 15% of the eggs we have tracked hatch before being eaten and less than 5% of those hatched eggs survive to become butterflies themselves.

Knowing more specifics about how milkweeds in tallgrass prairies contribute to monarch population growth is an important step to bringing monarch populations back from the brink of extinction.