Butterfly garden fuels migrating monarchs and student research

Linda Fink teaching at butterfly garden.
Dorys McConnell Duberg Professor of Ecology Linda Fink’s fall biology lab involves butterfly feeding, which gives students the opportunity to handle live insects.

Just past the train station on Sweet Briar’s campus, in the midst of an expansive green field, is a living compass. Special visitors migrate to this flower-filled compass from late summer to early fall every year on their long journey south. After drinking their fill, the winged guests continue their path to Mexico. Commonly known as the monarch butterfly, these visitors give the Sweet Briar community the gift of not only beauty, but also educational opportunity.

Sweet Briar College Dorys McConnell Duberg Professor of Ecology Linda Fink devised the compass in the late 1990s with her husband, Lincoln Brower, a world-renowned expert on monarch butterflies. With environmental funds and approval from then-President Betsy Muhlenfeld, they planted white, pink and lavender Buddleia davidii bushes, commonly known as “butterfly bushes” or “buddleias,” to create the distinctive garden seen today. The intent was to create a place where they could monitor the monarch butterfly population and observe and collect data to discuss with other scientists across the country.

The Sweet Briar butterfly garden also is a safe place for monarchs to nourish themselves for their journey south, a trip totaling almost 3,000 miles from start to finish. Fink makes sure to get that point across.

“What monarchs need for their migration is an abundance of sugar fuel to get them on their way to Mexico,” she says. “We wanted flowers that would be blooming through migration season and would be predictable and abundant.”

Monarch butterfly feeding at Sweet Briar's butterfly garden.
Fewer monarchs visit Sweet Briar’s campus due to declining numbers.

Regarding the shape of the garden, Fink says, “It was designed as a compass with the four arms pointing North, South, East and West to encourage visitors to pay attention to the directionality of the monarch’s migration to Mexico. On good days, you can see the butterflies flying in from the north and flying out towards the south.”

When she takes her students out to the garden, Fink encourages them to use the compass to orient themselves. She asks students to figure out which way their home is, and tells them that any time they feel homesick, all they have to do is come out to the garden to find their direction.

While adding to the beauty and life of Sweet Briar’s campus, the garden’s role in Fink and Brower’s research remains important — especially as the butterfly’s numbers decline. Brower is one of several scientists petitioning for protection of the monarch as a threatened species under the U.S. Endangered Species Act.

Since 1990, North America has lost 82 percent of its monarch population, according to the Center for Biological Diversity. There are an estimated 56.5 million monarchs today compared to more than 1 billion in the 1990s. Multiple factors affect this rate. Milkweed (the monarch caterpillar’s only food source) is being depleted by herbicide use that kills the plants. Logging in the monarch’s Mexican wintering grounds is also destroying their safe winter habitat. In addition, climate change may be playing a role.

Harsher winters and summers might negatively impact the butterflies, and the butterfly bush bloom cycle may be shifting so that they are flowering earlier. This presents a challenge for Fink and Brower: Will the bushes at Sweet Briar still be flowering when the monarchs come through? Volunteers play a major role to ensure that they do. Through late summer, including during Sweet Work Weeks, local naturalists and alumnae volunteers help “deadhead” the bushes — removing flowers that have already withered — so that the plants will stay in bloom when the monarchs need them.

Fink and Brower have monitored the monarchs from August to October for more than 20 years by conducting a daily census. One of the pair, or a student, will walk around the garden once, counting the number of monarchs they see flitting among the flowers. What they have recorded has astounded them. While monarch butterflies appear predictably at the garden each autumn, their numbers are declining.

A swallowtail feeds at Sweet Briar's butterfly garden.
A swallowtail feeds at Sweet Briar’s butterfly garden.

“We know that throughout the whole eastern United States, for the monarch butterflies, the trend is downward,” Fink says. “It is very serious — and unfortunately, we do not see their populations rebounding quickly.”

The loss of monarchs also has implications for student research. The monarch is the only butterfly that undertakes a long-distance, two-directional migration. Individual butterflies only make the round trip once in their lifetimes, with their great-great grandchildren following the same path the following fall.

This migrating generation of monarchs can live as adults up to six months — far longer than the lifespan of two weeks or less for most adult butterflies.

These characteristics provide an interesting educational background for researchers and students to work with. When the monarch population was higher, some biology students at Sweet Briar completed senior research projects on them. Now, there’s no guarantee a student will be able to capture enough monarchs for some research, depending on its requirements.

One of Fink’s first introductory biology labs each fall semester involves butterfly feeding, when students can handle live butterflies. This hands-on experience gives students a chance to interact with the insect world in a unique way. By carefully taking hold of the wings, the students measure, weigh and record information about the insect. Then, they take a pin and gently uncurl the butterfly’s tongue until it touches a tube of sugar water. The students watch as the water level goes down, and record how much the butterfly drank. Then, at the end of the class, the students let the butterflies go. In years past, Fink planned some of her fall insect biology and introductory biology labs around the migration.

“Five or more years ago, [the feeding lab] was specifically about monarch feeding behavior in relation to their energy requirements during migration,” Fink says. “I had three weeks of labs where students would ask questions about monarch feeding, design their own experiments, and conduct those experiments. Now I can’t guarantee that I can catch enough monarchs for two lab sections of students.

“So I now do the butterfly feeding lab using several species of butterflies, especially the abundant tiger swallowtails. Thank goodness we have this garden and I can use it with my students to collect butterflies that we can study. It is always fun for me to see students who are leery of insects or leery of handling these living things get really excited about the question they are asking. They become much more comfortable, and they care a lot.”

Alumnae volunteers deadhead butterfly bushes.
Alumnae volunteers “deadhead” spent blooms from Sweet Briar’s butterfly bushes.

Fink’s fall feeding lab developed from an honors thesis by a former student, Serena Basten Kachinsky ’02. The professor adapted Kachinsky’s methods to make them appropriate for her upper- and lower-level courses, and praises the biology department for its strong tradition of mentored research.

Fink and Brower have deep appreciation for the immense landscape there is to explore at Sweet Briar.

“We use the land for education, conservation, teaching, and making people excited about the natural world,” Fink explains. “With 3,200 acres, we can offer students practical experience. There are economic questions, there are conservation questions, and there are scientific questions.”

As the length of each day and the temperature change, monarch butterflies receive the signal that winter is on its way. On campus, we may no longer see the hundreds of monarchs that used to visit the buddleias, but there are still afternoons in September when several dozen might be visiting at once. They flit around the fragrant blossoms and alight gracefully upon a flower for a few seconds, drinking their fill of nectar. Other insects fly amidst the blossoms. Every now and again, a visitor just might spot the distinctive orange-and-black pattern of a monarch. Generations of them continue to find their way to Sweet Briar College each year, knowing it is a safe place to feed and rest.

Want to help monarch butterflies, or watch their migration? Visit Monarch Watch.

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