Monarch Migration Mystery
The tiny monarch butterfly makes one of nature’s most amazing migrations.
Biology, Experiential Learning, Geography, Physical Geography
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It’s early November, and Pacific Grove is preparing for thousands of visitors.
Calling itself “Butterfly Town, USA,” the small community on California’s Monterey Peninsula has already held its annual Butterfly Parade, where local schoolchildren dress up like the insect . Currently, past a sign announcing “Caution: Butterfly Zone” and adjacent to the Butterfly Grove Inn, the Monarch Grove Sanctuary is hosting approximately 1,000 monarch butterflies that have arrived early to spend their winter in this 2.4-acre site.
A volunteer butterfly docent for the Pacific Grove Museum of Natural History, Jack Beigle helps human visitors spot the monarchs clustered on a stand of nearby eucalyptus trees. “They look like dead leaves in a U-shape,” he says, as he points a spotting scope towards the trees. “They are all butterflies.”
He’s right. Above the tree trunks is a congregation of what at first appear to be clumps of dead leaves. But then a breeze causes the monarch butterflies to flutter their wings—revealing a blast of bright orange color.
Nearby, several butterflies float up into the sky. “We have a few flying,” Beigle says. “They can’t fly if their temperature gets below 55 degrees.”
Warmer winter temperatures bring monarch butterflies to almost 200 overwintering sites on the California coast , including Pacific Grove’s Monarch Grove Sanctuary, Santa Cruz’s Natural Bridges State Park, and the state’s largest site for vacationing butterflies, the Pismo Beach Monarch Grove. The butterflies will stay along the coast from November through February.
As brightly colored monarchs float from the sky like confetti , Beigle explains the insects ’ amazing journey . The monarch butterflies have chosen this small swath of land in Pacific Grove for its mix of moderate temperature , humidity , and shelter from the wind.
Beigle says that the butterflies have traveled to Pacific Grove from 100 to 1,000 miles north and east of Pacific Grove. Most monarchs fly to the coast from the foothills of the Sierra Nevada mountains on the border between California and Nevada. In early spring, the butterflies will migrate back to their cooler homes in the Sierra Nevada.
Beigle lists a few facts about the migrating monarch that elicit gasps from the small crowd of people gathered around him. He notes that some monarchs have been clocked flying at 15 miles per hour in still air. They also have stamina : “Two hundred miles in a day is common,” he says. “It depends on the wind.”
Monarchs are also high fliers. “Pilots have even reported seeing them at 10,000 feet,” he says.
While the migration of North America’s west coast population of monarch butterflies is impressive , it’s the eastern population of the species that achieves one of nature’s greatest feats . (The two monarch populations are separated by the Rocky Mountains .)
The eastern population journeys all the way from the northeast corner of the United States and Canada to a single location in central Mexico’s Michoacán state. The migration for the insect can be up to 3,000 miles.
Migration Mystery
One aspect of the monarch butterfly ’s migration that has long puzzled scientists is how the tiny insects navigate such extended journeys . A neurobiologist at the University of Massachusetts Medical School, Dr. Steven Reppert, has been researching the monarch butterfly ’s migration for years.
Reppert believes the insects use the sun, or rays of the sun, to determine their location. Specific chemical proteins in the butterfly’s brain help it to use the sun as a compass . Monarchs can interpret the sun’s position in the sky to help them fly from the northern United States, through Texas, and into Michoacán.
University of Minnesota professor Karen Oberhauser has studied the monarch butterfly for 25 years. Oberhauser is still amazed that an animal the weight of a single paper clip can complete such a long journey .
“I think the most impressive thing is that something that size can fly that far and find a specific spot in the mountains of Mexico, leaving this large, large area and congregating in this very small area,” she says.
Oberhauser is concerned about obstacles to the migrating monarch butterfly . “Probably the worst danger they can encounter is a lack of habitat , because they need to eat while they are migrating,” she says.
Monarchs’ favorite food is milkweed , which many farmers and homeowners consider a pest . “If all [the butterflies] are going over is agriculture fields and cities and suburbs with lawns , they are not going to find anything to eat. Probably the greatest cause of mortality during the migration is starving to death.”
The eastern population of the monarch butterfly not only travels farther than the western population, more butterflies make the trip. According to Oberhauser, an estimated half a billion monarchs spend the winter in central Mexico.
“All of the butterflies in all of the overwintering sites along the coast of California are many, many fewer than the butterflies in the Mexican overwintering sites ,” Oberhauser says.
Back in Pacific Grove, Beigle impresses a small crowd with more information about the western monarch butterfly migration while being sure to mention the even larger journey occurring on the other side of the Rocky Mountains .
“We feel good when we get 40,000 to 50,000 butterflies here,” he says. “They get millions down in Mexico.”
Family Vacation
According to National Geographic, only monarchs born in late summer or early fall make the winter migration, and they make only one round trip. By the time next year’s winter migration begins, several generations will have lived and died and it will be the great-grandchildren of last year’s migrators that make the trip. Yet somehow these new generations know the way and follow the same routes their ancestors tooksometimes even returning to the same tree.
Watch Out
Monarch butterflies’ distinctive bright orange coloring is a warning to predators such as birds and reptiles. Monarchs are bad tasting and upset predators’ digestive systems.
Monarch Butterfly
The large and brilliantly-colored monarch butterfly is among the most easily recognizable of the butterfly species that call North America home. They have two sets of wings and a wingspan of three to four inches (7 to 10 centimeters). Their wings are a deep orange with black borders and veins, and white spots along the edges. The underside of the wings is pale orange. Male monarchs have two black spots in the center of their hind wings, which females lack. These spots are scent glands that help males attract female mates. Females have thicker wing veins than males. The butterfly’s body is black with white markings.
Monarch caterpillars are striped with yellow, black, and white bands, and reach lengths of two inches (five centimeters) before metamorphosis. They have a set of antennae-like tentacles at each end of their body. The monarch chrysalis, where the caterpillar undergoes metamorphosis into the winged adult butterfly, is a beautiful seafoam green with tiny yellow spots along its edge.
Monarch butterflies are found across North America wherever suitable feeding, breeding, and overwintering habitat exists. They are broken into two populations separated by the Rocky Mountains, called the eastern and the western populations.
Whether monarchs are present in a given area within their range depends on the time of year. They are one of the few migratory insects, traveling great distances between summer breeding habitat and winter habitat where they spend several months inactive. In the summer they range as far north as southern Canada. In the fall the eastern population migrates to the cool, high mountains of central Mexico and the western population migrates to coastal California, where they spend the entire winter.
The population east of the Rocky Mountains contains the majority of the North American monarch population, which completes its northward migration through successive generations. They are found in the highest concentrations along a migratory flyway corridor through the central United States. In spring the monarchs leave overwintering grounds in Mexico and migrate north into Texas and the Southern Plains, then up through the Northern Plains and the Midwest, and finally up into the Great Lakes region. By late summer, eastern monarchs have spread north into Canada and eastward from the central migratory corridor throughout the Northeast and Southeast states.
From September into early October, fall southern migration to Mexico begins, with the majority of monarchs following the reverse path south along the central migratory corridor. Monarchs from the Northeast head south along the Atlantic coast, concentrating in the states that make up the Delmarva Peninsula between the Atlantic Ocean and the Chesapeake Bay on the journey. Florida is a stop for many monarchs before they fly over the Gulf Coast to Mexico. A much smaller population of monarch butterflies lives west of the Rocky Mountains. During summer, western monarchs live in canyons or riparian areas of the West, Southwest, inland California, and the inland Northwest states up to British Columbia. A small number of monarchs can be found in the coastal Pacific Northwest during summer months. Instead of making the long journey to Mexico, western monarchs only migrate as far south as coastal areas of central and southern California.
There are populations of monarchs in Hawaii, Puerto Rico, and some islands of the Caribbean, as well as in New Zealand. Monarchs may have been blown to these place in storms or naturally dispersed there by island-hopping, or they may have been introduced by humans. These populations are not part of the annual migrations on the North American mainland.
Monarchs, like all butterflies, have a different diet during their larval caterpillar phase than they do as winged adults. As caterpillars, monarchs feed exclusively on the leaves of milkweed, wildflowers in the genus Asclepias. North America has several dozen native milkweed species with which monarchs coevolved and upon which they rely to complete their life cycle.
Milkweed produces glycoside toxins to deter animals from eating them, but monarchs have evolved immunity to these toxins. As they feed, monarch caterpillars store up the toxins in their body, making them taste bad, which in turn deters their predators. The toxins remain in their system even after metamorphosis, protecting them as adult butterflies as well.
As adults, monarchs feed on nectar from a wide range of blooming native plants, including milkweed.
Monarchs lay their eggs on milkweed, their only caterpillar host plant. It takes three to five days for the egg to hatch. After hatching and consuming their empty egg case, monarch caterpillars feed exclusively on milkweed. The caterpillars grow and molt several times over roughly a two-week period and then form a chrysalis in which they undergo metamorphosis. After approximately another two weeks within the chrysalis, they emerge as adult butterflies.
Most adult monarchs only live for a few weeks, searching for food in the form of flower nectar, for mates, and for milkweed on which to lay their eggs. The last generation that hatches in late summer delays sexual maturity and undertakes a spectacular fall migration, one of the few insects to do so. This migratory generation can live upward of eight months.
The annual monarch life cycle and migration begins at the monarchs’ overwintering grounds in Mexico (for the eastern population) and the central to southern California coastal region (for the western population). Around March, the overwintering monarchs begin their journey north. Once migration begins, monarchs become sexually mature and mate. The females begin their search for milkweed plants on which to lay eggs. After mating and egg-laying, the adult butterflies die and the northward migration is continued by their offspring. It takes three to five generations to repopulate the rest of the United States and southern Canada until the final generation of the year hatches and does the return journey to the overwintering grounds.
The monarch migration is one of the greatest phenomena in the natural world. Monarchs know the correct direction to migrate even though the individuals that migrate have never made the journey before. They follow an internal “compass” that points them in the right direction each spring and fall. A single monarch can travel hundreds or even thousands of miles.
The monarch population has declined by approximately 90 percent since the 1990s. Monarchs face habitat loss and fragmentation in the United States and Mexico. For example, over 90 percent of the grassland ecosystems along the eastern monarch’s central migratory flyway corridor have been lost, converted to intensive agriculture or urban development. Pesticides are also a danger. Herbicides kill both native nectar plants where adult monarchs feed, as well as the milkweed their caterpillars need as host plants. Insecticides kill the monarchs themselves. Climate change alters the timing of migration as well as weather patterns, posing a risk to monarchs during migration and while overwintering. The U.S. Fish & Wildlife Service is currently reviewing the species’ status.
One easy way to help monarchs is to participate in the National Wildlife Federation’s Garden for Wildlife program by planting a pesticide-free monarch habitat garden filled with native milkweed and nectar plants. North America has several dozen native milkweed species, with at least one naturally found in any given area. Use these regional guides to the best native nectar plants and milkweed for monarchs in your area. Listed plants are based on documented monarch visitation, and bloom during the times of year when monarchs are present, are commercially available, and are hardy in natural growing conditions for each region. You can get information about additional butterfly and moth host plant species native to your zip code using the Native Plant Finder.
Planting locally native species is the best option for helping monarchs because monarchs coevolved with native plants and their life cycles are in sync with each other. In the last decade tropical milkweed (Asclepias curassavica), a plant not native to the United States, has become an increasingly popular way to attract monarchs in garden settings. Tropical milkweed is ornamental and easy to grow, and has become one of the most available milkweed species in nursery trade. Monarchs happily lay eggs on it. Despite these qualities, when planted in southern states and California, tropical milkweed can encourage monarchs to skip their migration and continue to breed through the winter, potentially putting them at risk for disease and other complications that they would have avoided by migrating. The National Wildlife Federation encourages planting native milkweed and cutting back tropical milkweed in the fall to encourage monarch migration.
In addition to the Garden for Wildlife program, National Wildlife Federation campaigns such as Butterfly Heroes engages kids and families in bringing awareness to the declining monarch population and gets them involved in helping monarchs and other pollinators. Through the Mayors’ Monarch Pledge, cities and municipalities are committing to creating habitat and educating citizens about how they can make a difference at home for monarchs.
Roadsides also offer habitat and respite for migrating butterflies and are the focus of a coordinated Monarch Highway effort by the National Wildlife Federation and partners along Interstate I-35, located along the monarch’s central migratory flyway. The National Wildlife Federation also works with the agriculture community and lawmakers to protect and to increase monarch habitat and declining grassland ecosystems.
The National Wildlife Federation recommends that the best way to help monarchs is by restoring their natural habitat by planting native milkweeds and nectar plants, eliminating pesticides, and encouraging others to adopt these practices. Due to the risks of spreading disease, limiting healthy genetic diversity, and bypassing natural selection, the National Wildlife Federation does not support the rearing of monarch caterpillars in captivity, or the mass release of commercially farmed butterflies.
Monarch butterflies communicate with scents and colors. The males attract females to mate by releasing chemicals from scent glands on the hind wings. Monarchs signal to other animals that they are poisonous by having bright orange wings. The bright colors serve as a warning that predators should attack at their own risk.
Monarch Butterfly, Mini Block Print, Limited Edition, pollinator art
About the Design:
“Monarch Butterfly” is the first in a series of native pollinators that I am creating. It takes inspiration from biological specimen drawings, but with a folk art touch to it. It is pulled using 5 different ink colors, mixed and blended onto two seperate “blocks” and hand block printed in 2 layers.
Item Details:
This particular print is made from a hand carved soft linoluem printmaking block.
The printed area of this artwork measures approximately 7 Inches wide by 5 inches tall.
Includes a custom cut, acid free matboard and backing board which measures 8×10 on the exterior and will fit into widely available standard frames.
The thick, archival printmaking paper used is sustainably forested, and made using 100% wind energy during the manufacturing process.
The inks used are all made right here in beautiful NC 🙂
Each Limited Edition print is signed and numbered in pencil by me.
All New South limited edition blocks are limited to less than 100 imprints, including all editions and artist proofs, ensuring that every piece is special.
About New South Pattern House:
At New South Pattern House, my priority is to deliver the most environmentally friendly and high quality products possible. I have thoroughly researched everything from my inks to my packaging materials so that you can relax and shop with the confidence that I have put in the work to deliver ethically sound art pieces that will last for years to come. Here are a few of the highlights:
All shipping/packaging materials are 100% compostable and/or recyclable
All block prints made in a solvent free studio
All paper used is both acid free, and sustainably produced, prioritizing sustainable forestry practices, and renewable energy manufacturing.
Prints are made to order or in small batches, reducing studio paper waste
About Block Printing:
Block prints often have slight textures and variations in the finished products. I think that’s why I love them– each one is special. Please be aware that, while I aim for consistency within each edition, there may be slight variations with each print and colors may differ from your computer screen.
Shipping and Production:
Please allow up to a week of time for your artwork to be printed and to dry thoroughly. If you need a faster turnaround time, message me and I’ll do my best to accommodate you.
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