Homestead Magazine Spring 2009: The Monarch migration

In the fall of every year, anxious nature lovers across North America await the news from counterparts in isolated mountain villages in central Mexico: Las Monacas estan aqui! The Monarchs have arrived!

That announcement marks the culmination of one of the most amazing of all nature’s wonders—the annual migration of the Monarch butterflies. From the coastlines of New England to the prairies of Canada and the plains of Kansas, tens of millions of seemingly frail Monarch butterflies make a treacherous journey of up to 3,000 miles. From 250 million acres east of the Rocky Mountains, they congregate on 50 acres or less in Mexico. Then, after four to five months of inactivity, they start the return, hoping to reach the southern U.S. to lay eggs on milkweed plants and turn the journey over to new generations.

Eyes to the skies"The Monarch butterfly migration is the most spectacular in the world. Each fall they migrate to the same region in Mexico, even though they are several generations removed from those that left Mexico the previous spring. It's truly astonishing," says Elizabeth Howard, director of Journey North, a science education program that uses the Internet to track the migration.

The Monarchs' amazing feat has captivated a legion of butterfly lovers that includes thousands of scientists, backyard gardeners, and school children from across the continent. Participation is swelling in several volunteer efforts that monitor the migration and aid the Monarchs in their journey.

Conservation groups are also capitalizing on the charisma of the Monarch to raise awareness of the habitat concerns of other pollinators as well.

Three large-scale "citizen science" projects offer the opportunity to assist the Monarchs. With 27,000 registered participants, Howard's Journey North project is the largest (www.learner.org/jnorth).

"We call our volunteers 'citizen scientists' and they are proving to be very beneficial in helping understand the life cycle and habits of the Monarchs," says Howard, who is based in Norwich, Vt. "They report when the first migrating Monarchs reach their area. Through the Internet, this information is assembled into moving maps that can then be studied in conjunction with weather or environmental conditions that might hamper the progress of the migration. We also monitor the emergence of milkweeds in the spring as there is a close and very dynamic relationship between these plants and the Monarchs."

Howard says the project, which is funded by the Annenberg Foundation, provides an excellent learning opportunity. "Many of our participants are teachers, so hundreds of thousands of their students are learning about conservation and stewardship," she says.

Howard adds that last year, more than 60,000 of those students participated in a symbolic Monarch migration. Students in the U.S. and Canada sent paper butterflies to Mexican children, who cared for them in the winter and mailed them back when the real Monarchs headed back north in the spring.

"U.S. and Canadian children studied the region in Mexico where their butterflies were spending the winter. Meanwhile, Mexican children came to realize that the Monarchs were a world treasure and their winter sanctuaries needed to be preserved," she explains.

Tagging butterflies. Monarch Watch is another monitoring project where volunteers can lend a hand (www.monarchwatch.org). "Our project tags from 25,000 to 100,000 Monarch butterflies a year during the fall migration, depending on the population and the weather," says Chip Taylor, professor of ecology at the University of Kansas. "In a typical year, around 1% of these tags are recovered and these help to answer questions about how the Monarchs make their amazing journey."

Last year, tagging showed how quickly Monarchs travel when the wind and weather are right. A butterfly tagged in New Jersey on Oct. 9 was found three days later in Georgia—a distance of 558 miles away.

"We’ve been tagging Monarchs for 17 years and using the findings to educate policy makers and the public about factors impacting them," says Taylor. "And, it's also just fun to have an excuse to collect butterflies."

The Monarch Waystation project is an offshoot of Taylor's program. Participants receive a seed kit to provide habitat suitable for Monarchs within the context of a traditional garden. The kit includes six species of milkweeds to feed developing Monarch caterpillars and six nectar species to feed adults.

More than 2,800 Monarch Waystations are registered each year—some by schools and nature centers, but most by people just wanting to attract Monarch butterflies. "It’s just like in the movies, if you plant it—they will come," Taylor points out.

Plenty of them find their way to Doug and Mary Ellen Rudick's back yard in Salina, Kan. "We’ve planted two types of milkweed (butterfly and common) along with golden rod, blazing star, ironweed, and other perennials. Our yard was already certified in a song bird habitat program, and now we’re Monarch Waystation No. 1382 as well," says Doug.

Butterflies in peril. Their long migration isn’t the only thing about Monarch butterflies that citizen scientists are helping to study. At the University of Minnesota, wildlife biologist Karen Oberhauser conducts the Monarch Larva Monitoring Project (www.mlmp.org) — an effort involving volunteers from the U.S. and Canada. She also directs a related Monarchs in the Classroom program.

"Our volunteers document population changes over time to help us understand why they occur and what conditions favor the health of the Monarch population. This aids in our conservation efforts," she says.

Researchers estimate Monarch populations by measuring the surface area they occupy in their Mexican wintering sites. A dozen such sites have been identified and their combined size has been measured since 1994, when it covered 19.3 acres. Since then, the population has varied from a peak of 51.7 acres in 1996 to a low of 5.4 acres in 2004.

"This year, the Monarchs covered 12.5 acres," says Taylor. "Generally, the population is declining, primarily because of the loss of habitat in the breeding area of the U.S. and Canada and deforestation in Mexico."

Taylor says the rapid adoption of crops genetically modified to tolerate herbicides has led to the elimination of milkweeds in row crops. "It used to be that a few scattered milkweeds made row crop fields excellent breeding areas for Monarchs, but now 100 million acres of that habitat are gone. The rapid rate of development in the U.S. is also destroying 6,000 acres of habitat a day. We need to be protecting habitat on marginal land and establishing new habitat where possible," he says.

The loss of forest habitat in Mexico is a particular concern of Lincoln Brower, a biologist at Sweet Briar College who is widely regarded as the preeminent expert on the Monarch butterfly. "I first went to the overwintering area in Mexico in 1976, just after they were discovered. It was a life-changing experience for me and I’ve been captivated by the Monarch butterfly ever since," says Brower.

Brower says for future generations to share this fascination, more must be done to conserve the Monarchs. In the last 30 years, 23% of the forest in the critical area of Mexico has been removed and 44% has been degraded— a situation that likely contributed to loss of 80% of the Monarchs to a freeze in 2002.

"In 1986, a presidential decree in Mexico established a sanctuary to protect the area, but illegal logging is a problem. Three large scale illegal operations have taken place in the past five years. The impact of this deforestation, and the industrialization of agriculture in the U.S. and Canada, are major threats. Because of them, the amazing migration of the eastern Monarch species is an endangered biological phenomenon," says Brower.