Little Butterfly, Big Journey

Director's Note: Our two seasonal naturalists for 2020, Katherine Culbertson and Jack McDonough, are preparing a series of blog posts designed to educate readers about many aspects of monarch biology and related topics.  We will still post updates and summaries on the state of the migration through Cape May, but we hope readers will find these additional posts to be both interesting and informative.  The first from this series was written by Katherine Culbertson, titled: 

Little Butterfly, Big Journey: A little bit about monarch migration and why it matters

Monarch in flight, photo by Jack McDonough

Monarchs are starting to roll through Cape May on their fall migration! While we’re still a ways out from the peak of their migration, monarchs are becoming more commonplace around the Cape, especially in some of the most elaborate native flower gardens. But where did they come from? And where are they going? And why on earth does it matter? Chances are many of you already know the answers to these questions, but to get everyone up to speed, this blog piece – the first in a series of educational blog posts on monarchs – will set out to address these questions.

As you likely know, monarchs embark on a seasonal migration through North America each year. Most of the population will overwinter in Mexico, heading north as the weather warms in spring, and returning back south as cooler fall weather approaches again. However, no individual monarch will make the entire migration to Mexico and back; in fact, monarchs complete this journey over at least four generations! During the first four generations, the entire population migrates to the north, taking advantage of the expanding plentiful seasonal milkweed (caterpillar food) and nectar resources (butterfly food) of temperate climates. As the weather starts to change in the fall, the year's final generation – the monarch “super generation” – is born. These butterflies will make the journey all the way from their summer feeding grounds to overwintering sites in Mexico. They travel an average of 50 miles per day on their journey and live nearly 8 times longer than all of the previous generations. Of the monarchs you’re seeing now, some are still part of the last summer generation, which won’t actually make it to Mexico; their children, however, will. 

Monarch migration map courtesy of Monarch Watch

The migratory monarchs you are beginning to see now likely hatched out in coastal areas of the U.S. and Canada northeast of Cape May – places including New Brunswick, New England, and the eastern part of New York and Pennsylvania, or perhaps right here in New Jersey. Because the northeast part of North America tapers west as it goes south, many monarchs from the northeast regions travel due south until they reach the coast, and then continue to follow it as it tapers into Cape May, creating a sort of natural funnel for the butterflies. (This is the same reason that Cape May is an incredible birding spot, too!)

Some of the butterflies tagged here in Cape May in the past – at least 90 so far – have made it all the way to Mexico and been recovered there! Our butterflies have been found in several southern states along the flight path to Mexico, too, including Virginia, South Carolina, and Texas. Interestingly, some have ended up in Florida, as well, possibly assimilating into the year-round populations found there. It’s unclear why some monarchs from Cape May end up in Florida, while others make it to Mexico. Did those in Florida end up there intentionally? Or did they simply lose their way on their journey to Mexico, or get detected there en route? Scientists are still trying to figure this out!

Roosting monarchs at Cerro Pelon Sanctuary, Mexico. Photo by Mark S. Garland

Now, the question you’ve all been waiting for: Why is it important to track migrating monarchs? Every monarch enthusiast may have their own unique answers, but I’d contend that tracking monarchs is important for two main reasons: First, monarchs serve as great biological indicator species; second, they are great science education “ambassadors”. 

As an indicator species, tracking the health of monarch populations can help us assess the health of the broader ecosystems they depend on. Because monarch populations need a vast expanse of habitat to successfully complete their multigenerational migration, they are one of the first species to suffer from habitat degradation and fragmentation. They are also easy to see and track, unlike many other less visible species dependent on the same habitat. A decline in monarch populations indicates that something is going wrong across the North American landscape, hopefully motivating actions to improve conservation and habitat restoration before many species are adversely affected.

Katherine Culbertson at age 8, photo by Chris Culbertson

As a “science ambassador”, monarchs hold the power to help people of all ages learn about our incredible natural world. Monarchs are easy to spot, can be found throughout the United States, are easy to raise, and venture on a truly incredible and inspirational journey. We don’t have to go out of our way to encounter them, monarchs can help teach us about migration, conservation, metamorphosis, and so many other things right in our very own backyards and nearby parks. We can all participate in tracking monarchs, too, through the Monarch Watch and Journey North nationwide citizen science projects. It’s especially magical for children to get involved in raising and providing habitat for these butterflies, generating a deeper understanding of and appreciation for nature. I, for one, can trace my love of science and nature back to my childhood adventures raising many a monarch caterpillar! It’s truly incredible to think a creature so small can travel so far – quite an inspiration for all of us, and a marvel of one of the many mysteries of the natural world!