Monarch Butterflies

Migration Update: October 23, 2008

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Latest News: A Wave Across Northern Mexico and a Trickle at the Finish Line

Northern Mexico
Monarchs appeared across the skies of northern Mexico on Saturday all at once. "Las monarcas están aquí! (The monarchs are here!)," wrote Rocio Treviño from her hometown of Saltillo, Coahuila. Simultaneously, people across town began to see monarchs. It was October 18th, the same date they reached Saltillo last year in large numbers. That evening, Rocio discovered a spectacular roost (see photo). Throughout the day, her network of observers were sending sightings from the states of Coahuila, Nuevo Leon, Zacatecas and Tamaulipas. "The spectacle was a gift for my eyes," wrote a woman in Tamaulipas who counted 537 monarchs per minute. Monarchs were even reported from Mexico City. (Monarchs form a small overwintering colony east of Mexico City each year, 70 miles from the major overwintering area.)

Grab your Spanish/English dictionary because the monarchs are now crossing northern Mexico! Thanks to Rocio Treviño, you can explore more sightings from Mexico and practice Spanish:

At the Finish Line
Estela Romero and German Medina have been watching and waiting in Angangueo. They know the monarchs usually appear first on a hillside above town called "El Cerrito."

"We went at noon today to El Cerrito. In about 30 minutes, we counted six monarchs flying quickly by!" Estela wrote on Wednesday. "Any day the trees on this hillside will be covered with monarchs. I am sending this photo for all to see that the trees are still empty."

More Monarchs are Coming!
Monarchs are contining to migrate from points across the north, say observers from Wisconsin to Maine. Along the Atlantic Coast, last week's migration at Cape May, New Jersey, was one of the season's strongest. An average of 53+ monarchs per hour were counted by the Cape May Monarch Monitoring Project, according to project leader Dick Walton.

Too Late to Migrate?
People are worried that monarchs will get caught by cold temperatures and will not be able to migrate. There is hope! A discovery last week by Dick Walton's team shows how quickly monarchs can travel when the wind and weather are right:

A monarch they tagged in New Jersey on October 9th was found in Georgia just 3 days later. That's a distance of 558 miles!

Let's hope for more warm days in the north so the remaining monarchs can escape. If you still have butterflies to release, wait for a stretch of sunny days with temperatures in the 50s F.

Funnelling Across Texas and Into Mexico
The monarchs are forming a funnel as they cross the state of Texas and enter Mexico. The pathway they have taken so far is known as the "Central Flyway" in Texas. But there appear to be two migration pathways in Texas. The monarchs arrival on the second flyway, called the "Coastal Flyway" lags behind. Right now we're waiting for large numbers of monarchs to travel along the Texas coast:

"Last year we had our big flow start on October 24th and the year before on October 28th. Our rule has been it will start after the first front that passes through on or after October 21st," reports Harlen Aschen from the Texas coast.

Stiff north winds are predicted for tomorrow (Friday) so keep your eye on the migration map. "For those of you along the Texas coast, the orange wave may yet appear!" added Harlen.

This Week's Highlights


Photo by Rocio Treviño
Coahuila
 With 400 miles left to fly, these monarchs were resting at roost in Saltillo, Coahuila on October 18th. >>

Photo by Estela Romero
Michoacan
 Empty trees at the finish line! This mountain meadow called El Cerrito is one of the first places people of Anangueo see monarchs.

For Your Journal: Explore this week's sightings from Mexico!

Tagged monarch found!
 How long quickly did the monarch fly 558 miles?
The Migration: Maps, Data and Questions

Monarch
Fall Roosts
 (map/sightings)

Monarch
PEAK Migration
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ALL Monarch
Migration Sightings
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Distribution Map >>

About these maps >>

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Make your own map >>

This Week's Map Questions >>
Related Journey North Lessons and Links

Monarch Butterfly Migration Updates Will be Posted on THURSDAYS: Aug. 28, Sep. 4, 11, 18, 25, Oct. 2, 9, 16, 23, 30, Nov. 6...or until the monarchs reach Mexico!

The Next Monarch Migration Update Will Be Posted on October 30, 2008.

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