Monarch Migration South

The Epic Journey Begins



The Amazing Monarch Butterfly (Danaus plexippus)

We learn at a young age that these butterflies migrate, and truly are the only insect of North America that migrates long distance.

Indeed, it is the only true migrating butterfly of North America.

Unlike most other insects in temperate climates, these butterflies cannot survive a long cold winter. Instead, they spend the winter in roosting spots.

Monarchs West of the Rocky Mountains travel to small groves of trees along the California coast.

Those east of the Rocky Mountains fly farther south to the forests high in the mountains of Mexico.

From Nova Scotia and Maine, Ontario, Michigan, Minnesota, North Dakota, Saskatchewan, Alberta, Montana, Washington, British Columbia and parts between.

The Monarch's migration is driven by seasonal changes.

In late August and early September, the urge to move takes flight.

Day-length and temperature changes influence the movement.

In all the world, no butterflies migrate like the Monarchs of North America.

Yes, we are blessed to have these insects and the opportunity to experience all that they do.

They travel much farther than all other tropical butterflies, up to three thousand miles.

They are the only butterflies to make such a long, two way migration every year.

Monarch Emerging

When the late summer and early fall Monarchs emerge from their pupae, or chrysalides, they are biologically and behaviorally different from those emerging in the summer.

You might say they are like adult sized kids. Big enough, but not able to reproduce right now.

The shorter days and cooler air of late summer trigger changes. In the northern extremes of its territory, this occurs around the end of August.

Even though these butterflies look like summer adults, they won't mate or lay eggs until the following spring.

Instead, their small bodies prepare for a strenuous flight.

Otherwise solitary animals, they often cluster at night while moving ever southward.

Like birds, they take off when there is abundant food and warm weather. No pushing the panic button to head South.

But, if they linger too long, they won't be able to make the journey; because they are cold-blooded, they are unable to fly in cold weather.

40 degrees above zero and they are paralyzed.

Fat, stored in the abdomen, is a critical element of their survival for the winter.

This fat not only fuels their flight of one to three thousand miles, but must last until the next spring when they begin the flight back north.

Some researchers now believe that this butterfly conserves their "fuel" in flight by gliding on air currents as they travel South.

Amazingly, they fly in masses to the same winter roost, often to the exact same trees their ancestors from a year ago were in.

Their migration is more the type we expect from birds and some mammals.

However, the butterflies make the trip just once.

It is their great grand children and great, great, great, grand children that return south the following fall.

Monarch butterfly

Some other species of butterflies and moths travel long distances, but they generally go in one direction only.

And that is often following food.

This one-way movement is properly called Emigration.

In tropical lands, butterflies do migrate back and forth seeking food as the seasons change.

How Scientists Study Monarch Migration:

In 1937, Frederick Urquhart was the first scientist to tag these butterflies in a quest to learn about their migration.

In the 1950’s, he recruited a handful of volunteers to help in the tagging and monitoring efforts.

Tagging and research is now conducted by several universities with the help of thousands of volunteers, including school children and their teachers.

One tagged butterfly was tracked along a 1,870-mile route. Originally tagged on September 18, 1957 in Highland Creek, Ontario, it was spotted again in San Luis Potosi, Mexico, four months later.

In 1998 at least 35 butterflies were reported with tags. One such butterfly had flown at least 1,844 miles southwest from where it was tagged in Campbell, MN, to its roosting spot in El Rosar io, Mexico.

tagged monarch

Experts now know that they don't fly in a straight line.

The tags used today are small adhesive stickers, each printed with a unique ID number and contact information for the research project.

The tag is placed on the butterfly’s hind-wing, not impede flight.

A person who finds a tagged butterfly can report the date and location of the sighting to the researcher.

The data collected from each season’s tags provides scientists with information about the migration path and timing.

In 1975, Frederick Urquhart is also credited with finding the wintering grounds in Mexico, which were unknown until that time.

The site was actually discovered by Ken Brugger, a naturalist volunteering to help with the research.

Energy-Saving Strategies:

Scientists discovered that migrating butterflies actually gain weight during their long journey.

They store fat in their abdomens, and use air currents to glide as much as possible.

As they migrate southwards, the butterflies stop to nectar, and they actually gain weight during the trip!

Often they will stay for several days at what are called way stations.

Several butterflies will feed and sleep together in these way stations until the time is right to move on.

These energy-saving strategies, together with feeding on nectar throughout the trip, help the migrants survive the arduous travel and long stay over before heading North in the spring.

Indeed, some northern, tagged butterflies that were captured in Texas two months later, weight an incredible 60% more than pre or early migration weight.

Your yard may very well be one of these important stops. If not and you would like it to be, start adding nectar flowers that attract Monarchs and offer protection from the weather.

The Day of the Dead:

The Monarchs arrive at their Mexico wintering grounds by the tens of thousands in the final days of October.

Their arrival coincides with "el Dia de los Muertos", or the "Day of the Dead," a Mexican traditional holiday that honors the deceased.

The indigenous people of Mexico believe the butterflies are the returning souls of children and warriors.

How do they do it?

The phenomenon of long-range bird migration is a well-known one, but not in the insect world.

Also, among birds their migration route is a round-trip one, which they make more than once in their lifetimes.

For the Monarch it is strictly a one-way trip for each butterfly.

How do these creatures do it?

The "Creator's" mystery of the mechanisms involved in this remarkable phenomenon has apparently been resolved.

A team of scientists who did this by exploring the infinitesimal butterfly brain and eye tissues to uncover new insights into the biological machinery that directs this delicate creature on its lengthy flight path.

The research team, led by Prof. Steven Reppert of the University of Massachusetts Medical School, included Dr. Oren Froy, now of the Faculty of Agricultural, Food and Environmental Quality Sciences of the Hebrew University of Jerusalem.

Others involved were from the Czech Academy of Sciences and the University of California, Irvine. Their latest findings were published in a recent issue of Neuron magazine, constituting a continuation of their earlier work, published in the journal Science.

In short, a global effort.

Wall to wall monarchs

While light in general is essential to the functioning of the "biological clock" in the butterfly brain – governing its metabolic cycles, including its "signal" to migrate.

The researchers discovered that it is specifically the ultraviolet band of light that is crucial to the creature's orientation.

The Monarch butterflies have special photoreceptors for ultraviolet (UV) light in their eyes which provide them with their sense of direction.

They proved that this ultraviolet "navigation" is crucial by placing butterflies in a "flight" simulator. When a UV light filter was used in the simulator, the butterflies lost their orientation.

Further probing revealed a connection between the light-detecting navigation sensors in the butterfly's eye and its brain clock.

It was shown that input from two interconnected systems – UV light detection in the eye and the biological clock in the brain -- together guide the butterflies "straight and true" to their destination at the appointed times in their two-month migration over thousands of miles/kilometers.

Amazing how 'God' makes and designs things and allows for us to discover some of his handy work when the time is right.

Survival of the fittest:

Science Daily (Mar. 11, 2005)

Monarch butterflies in eastern North America have one of the longest migrations of any species, with a survival-of-the-fittest trek that can take them thousands of miles from Canada to Central Mexico.

A new Emory University study has found that these journeys may be the key to maintaining healthy monarch populations at a time when habitat loss and other environmental issues could curb the ability of the butterflies to make the trip.

Emory researchers discovered that butterflies infected with a protozoan parasite flew slower, tired faster and had to expend more energy flying than healthy monarchs.

These results, published in the March issue of Ecology Letters, may explain why parasite burdens are much lower in migratory populations compared to year-round residents. An effect that possibly occurs in other migratory species as well, explained Sonia Altizer, lead researcher of the study and an assistant professor of environmental studies at Emory.

It is estimated that one Billion butterflies start the Journey South and an estimated 200,000,000 make it to the wintering grounds.

While hibernating, great quantities are killed by weather (some years worse than others) and picked off by predators. Birds like Black-headed grosbeaks and Black-backed orioles—can eat adult butterflies in the overwintering colonies.

While grosbeaks are relatively insensitive to the cardiac glycosides, the orioles have figured out which parts of the bodies are safe to eat and avoid the most poisonous parts. Grosbeaks and orioles can kill more than 10% of the total monarch populations in a winter.

Monarch on butterfly bush

Some Good News:

We know every year like clockwork, Monarch butterflies in The United States and Canada pack their bags in late August and September and head to Mexico for their winter break.

The annual migration is a huge tourist attraction, and Mexico is working to further support it by expanding their nesting areas and curbing illegal logging in the region.

In 2007, with little fan fare, Mexico's President Felipe Calderón pledged 4.6 in American money toward advertising and equipment for the Monarch Butterfly Biosphere Reserve, which covers a 124,000-acre (50,000-hectare) swathe of trees and mountains that for thousands of years has served as the winter nesting ground to millions of orange-and-black-winged monarch butterflies.

Calderón said the plan would encourage tourism to an impoverished area where illegal logging has been rampant and still continues this day. The logging has depleted the foliage where insects – a.k.a. butterfly food – reside.

Fortunately, a staff of rangers "equipped with assault rifles and body armor," have been searching for gangs of lumber thieves, and their work has helped decrease logging in the area by 48 percent.

If nothing else, we must glad that tourism was the trigger that inspired Calderón to protect the forests and the butterflies as a result.

The Monarchs return to just 12 forested mountain tops in central Mexico, where they form colonies in which millions of butterflies cluster on the trunks and branches of the trees.

The western population overwinters in various sites in central coastal and southern California, notably in Pacific Grove and Santa Cruz.

Despite protected areas and reserves, illegal logging and other human-induced environmental changes have damaged and depleted the unique, critical Monarch habitat and pathway.

Although the butterfly is not in danger of extinction, its unique multi-generational migration spanning the continent is now recognized as an “endangered biological phenomenon”.

Since there are very few overwintering sites where the adults aggregate in great numbers, their populations become vulnerable.

Logging, development, and agriculture are the most serious threats.

Because this butterfly depend upon a wide range of habitats in Canada, Mexico and the United States, conservation of the migratory Monarchs requires trilateral cooperation due to threats to the butterflies' habitats throughout the flyway.

In 2007 the countries’ environment ministers called for the development of a North American plan to protect the Monarch.

Its objective is to maintain healthy populations and habitats throughout the migratory.

Monarchs were established in Australia around 1880 when Milkweed was brought in and established. Scientists wonder if the butterfly eggs came with the milkweed plants or somehow they island hopped and found a new home.

These butterflies also migrate.

Monarchs in tropical regions like Costa Rica and Hawaii have no reason to migrate.

Migration Time Table for the Journey South:

Latitude........ Midpoint.............. Peak in Monarch abundance.

49..............26 August................18-30 August

47............. 1 September.......... 24 August -5 September

45............. 6 September.......... 29 August - 10 September

43............. 11 September........ 3 - 15 September

41............. 16 September........ 8 - 20 September

39............. 22 September........ 14-26 September

37............. 27 September........ 19 September - 1 October

35............. 2 October................ 24 September - 6 October

33............. 7 October................ 29 September - 11 October

31............. 12 October.............. 4-16 October

29............. 18 October............. 10-22 October

27............. 23 October............. 15-27 October

25............. 28 October............ .20 October - 1 November

Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come.

2 Corinthians 5:17

Butterfly Friendly Yard.

Butterfly Plants and Flowers

Profile of a Butterfly

Monarch Facts

Return to Butterfly Main Page