As the cold weather sweeps down from Canada in September, millions of monarch will take flight to escape it. In three pathways, monarch butterflies will flood from the United States into central Mexico. One group flies from the west through Arizona and New Mexico. Another migrates from central Canada, the Midwest and Great Plains through central Texas. The final cluster will travel along the Appalachian Mountains and Atlantic seaboard to follow the Texas coast to Mexico. 

When the autumn season brings shorter daylight and cooler temperatures, the monarchs read these as signs that they need to stop reproducing and head to their winter home in Mexico. 

The butterflies will reach Texas by late September, and the number will peak during October. The largest migration concentrations will cross into Mexico around Del Rio in the last half of October. By Thanksgiving, most will have settled into their reserves in the mountainous oyamel fir forests. 

There was a drought through the Midwest and parts of central Texas this year. This resulted in sparse wildflowers and few natural nectar sources, which is what the butterflies are dependent on. The southern rains in southeast Texas, however, have produced many nectar-rich flowers. This means the monarchs will – thankfully – have sufficient food to nourish them when they arrive. 

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Imagine a monarch that has traveled the 3,000 from Canada to Mexico, and then only makes it to Texas on the return journey. Say she lays an egg there, and that egg born in Texas births a monarch that flies to South Dakota and lays another egg. That monarch hatches, and manages to find her way to Mexico come autumn. How did the monarch travel to the exact same grove in Mexico that her elder monarchs did? 

Some animals that migrate learn from parents. Other creatures orient by stars or landmarks. How do monarchs know where to migrate south? Scientists are still trying to find out.

Dr. Orley R. Taylor, a scientist who runs the Monarch Watch project at the University of Kansas, has studied this mystery. He has tested their ability to reorient themselves. He transported monarchs from Kansas to Washington, D.C. to see if they could still successfully navigate after a relocation of more than 1000 miles. If the monarchs are released immediately after being relocated, they take off due south as they would have from their original location. However, if they are kept in mesh cages for a few days, they watch the sun rise and set, and reset their internal compasses. 

Dr. Taylor cites that monarchs are one of the only species that have the ability to orient themselves in latitude and longitude. When the sun drops to approximately 57 degrees above the southern horizon at their specific latitude, monarchs begin their migration.

Professor of neuroscience at Queens University of Canada Dr. Barrie Frost does not believe monarchs use the earth’s magnetic field or the sky’s polarized light. Rather, he thinks the sun reckoning leads the butterflies south, while mountain chains and the Gulf of Mexico funnel them towards southern Texas. Dr. Frost also believes that once in Mexico’s mountains, they are guided by the smell of last year’s corpses. 

Dr. Taylor disagrees, citing that butterflies do not have odiferous fatty acids that would last a year and lead a new migration herd. Citing work by butterfly biologist William H. Calvert, Dr. Taylor says most monarchs cross central Texas. Dr. Taylor’s tagging work has also shown that a monarch tagged near the Atlantic or the gulf is just one-tenth as likely to reach Mexico as one tagged in the Great Plains.

How do you tag a small, delicate monarch? Dr. Taylor will gently pinch the butterfly in one hand, and place a tiny adhesive tag on a specific cell. He is then able to track the butterfly for the entirety of its life, and uses these tags to follow the annual migration.

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Many obstacles lie between the origin and destination locations for the monarch butterflies’ migration. There are plenty of predators. The cold weather is sweeping in. Food supplies are spread apart. The distance is up to 3,000 miles. But what hurts the monarchs the most is damage to their environment. Illegal logging, specifically, has caused unparalleled damage to their hibernating grounds in Mexico.

At the peak of logging in 2005, it ruined upwards of 1,140 acres annually in the reserve. It was considered the reserve’s largest threat. In the early- to mid-2000s, armed police began patrolling reserves for logging operations, and donor groups started local nurseries to help grow for hopeful reforestation. The improved governmental stand against logging helped cut down the deforestation, however individual tree removal remains practically undetectable. During the past couple years, the thinning of forests is still noticeable, and will continue unless year-round monitoring and guarding is enforced. 

Additional reserve harm is coming from climate change. Droughts cause the trees stress, and make them vulnerable to bark beetles. Heavy rain and windstorms can create mudslides. Mistletoe strangles trees. These conditions wipe out acres of forest that the butterflies need for shelter. 

The number of monarchs wintering in Mexico dropped 28 percent this year. Some experts attribute the loss to drought in the northern parts of the Americas, where monarchs spend their summers. But it is clear that measures still need to be taken to ensure ample migration space in Mexico.

Migration is a trait inherited by monarchs. A monarch’s lifespan is so short, that no butterfly lives to make the round-trip. These delicate creatures need their winter refuge in Mexico, where millions of the species cluster so densely on tree boughs that researchers count them in acres rather than individually. The number of trees lost annually to logging has decreased, but must continue to decrease to help the monarchs. Officials and locals in Mexico are continuing to work to protect the forests, and the orange and black butterflies that call them home. 

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Follow the monarchs’ perilous and extraordinary journey, and join hundreds of millions of real butterflies in the remote mountain peaks of Mexico. For the very first time, witness the transformation from caterpillar to butterfly. This includes being able to see inside a chrysalis, due to advanced MRI and micro CT scans. Become lost in the compelling story of a courageous scientist’s 40-year search to find the secret migration destination of monarchs.

This award-winning film team – including Oscar winner Peter Parks – followed the year-long migration cycle of the monarch butterflies. Experience the journey from Canada, through the United States, to a few remote, 10,000 foot high peaks in the Sierra Madre Mountains of Mexico, and back. This film captures the awe and wonder of the breathtaking sanctuaries, and interweaves spellbinding natural history with an uplifting human story. 

Experience the phenomenon. Unravel the mysteries. Witness the journey. Flight of the butterflies. 

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