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Monarch Butterfly Migration Update: October 28, 2005

Today’s Update Includes:

Latest Migration Maps
Make Your Own Map in the classroom!

Migration Sightings
Sightings of Overnight Roosts PEAK
Migration Sightings
Click for live maps and read what each observer saw! Also See
Week-by-week Migration Animation

Watching and Waiting at the Over-wintering Sanctuaries
Still no monarchs, says Estela Romero. Like clockwork, the butterflies have arrived at the same time every fall since ancient times. "The arrival of the monarchs were, for our ancestors in pre-Hispanic times, the souls of the dead coming back to earth to be for short time together with us." Next Tuesday is "Dìa de Muertos" (Day of the Dead). We'll let you know what happens!

Migration News From Northern Mexico
Hundreds of thousands of monarchs covered the trees and skies of Saltillo, Coahuila, and in the surrounding countryside on Tuesday and Wednesday, reports Señora Rocio Trevino:

Saltillo, Coahuila (25 N, -100 W)
"El frente frio numero 7 hizo llegar a Saltillo cientos de miles de mariposas, el dia 25 y 26 el cielo y los arboles se cubrieron de mariposas, las mariposas se encuentra por toda la ciudad y el campo. Ya he recibido reportes de San Luis Potosi y del estado de Zacatecas.

Still Coming Down From the North
Monarchs continued to pour down from the north last week. Here are more highlights, from south to north:

Texas Gulf Coast: The Wave Arrives

10/25/05 Port Lavaca, TX (28 N, -96W)
"The migration along the Coastal Flyway here at the mid-coast of Texas has suddenly gotten hot. This started with the first of two fronts last Friday, Oct. 21st. The best four-minute count of those flying across the causeway has been forty-six."

Florida Gulf Coast: Which Direction?

10/22/05 Perdido Key, FL (30 N, -87W)
"Last Saturday I stood among hundreds of monarch butterflies coming onto land from out of the Gulf of Mexico," wrote Sandra Burns who had been riding her motorcycle when she noticed the butterflies. “It was one of the most remarkable sights I have ever seen. Could Hurricane Wilma have blown them off course and back over land?"

This observation raises many interesting questions!

  • Had the butterflies been caught in hurricane winds?
  • Were they struggling to return to land?
  • Where did these monarchs come from?
Which direction do monarchs go when they hit the Gulf Coast in Florida?

What Can We Learn from 12,500 Monarchs?
Look at a map of the southeastern U.S. and imagine a monarch flying down from the north. Which way do you think it will go when it reaches the Gulf of Mexico? Almost 12,500 monarchs have been tagged there by Mr. Richard RuBino to try to answer that question. We plotted his tag recoveries on this map.

"I know for certain that, in the fall, monarchs passing through this area spread fairly equally to the west and southeast. We've had a few recoveries along the Gulf Coast to the west of us, and some recoveries southeast of us, down the peninsula. Since only 3 of the almost 12,500 monarchs tagged here since 1988 made it to Mexico, I fear that most of them end up in the middle of the Gulf of Mexico."

Atlantic Coast: Late and Large in Cape May
"A late and large wave of monarchs has moved through Cape May, New Jersey, over the last week," reports Dick Walton from the Monarch Monitoring Project. "Michael O'Brien tallied 445 monarchs on one of three daily census runs on 18 October." (A census run takes about 20-minutes.)

Too Cold and Dark to Fly? Challenge Question #9
Can these late-season, northern monarchs make it to Mexico? It's nearly November! Temperatures are falling and the days are becoming shorter and shorter. Monarch butterflies can not fly in the dark and they are paralyzed by cold temperatures.

"The minimum for flight is 57 degrees F," says Dr. Chip Taylor of Monarch Watch. "Monarchs will move when temperatures exceed 55 F with unobstructed sunlight, but need temperatures in the low 60's to move when it is overcast. Wind speed becomes more of a limiting factor at low temperatures due to convective heat loss. The monarchs have to maintain an elevated thoracic temperature to be able to sustain flight."

When and where could a monarch butterfly fly yesterday? When and where might cold and darkness trap them? Here are temperature forecast maps collected every 3 hours yesterday, and a link to sunrise and sunset tables.

Too Cold to Fly Yesterday?

8 am 11 am 2 pm 5 pm
Maps from: NOAA Sunrise/Sunset Look-up

Challenge Question #9:
After reading today's update:

Challenge Question #9:
"Could a monarch butterfly in New Jersey fly yesterday at the following times: 8 am, 11 am, 2 pm, 5 pm, 8 pm? Answer yes, no, or maybe, and explain your thinking. (For simplicity, assume that the sky was cloudy all day.)"

Discussion of Challenge Question #7: How High?
We asked, "How high were the monarchs flying by the 54th floor window in downtown Dallas? Had you been standing on the ground could you have seen them with binoculars? With the naked eye?"

"They were flying at 685 feet," figured Augustin of Saylorsburg, PA. "I could not see it from the ground with binoculars or without." Here is how he found the answer: "I figured this out by finding the height of the building at Wikipedia. I used the height of the 56 stories as built in 1974, which is 710 ft. I divided to find the height of 1 floor, then multiplied by 54.

Discussion of Challenge Question #8: Geography and Migration

Grade 4 students of Heritage Elementary in Wake Forest, North Carolina, "learned many things about the geography of Mexico. Two of the things we learned: 1) one of the geographical features that influences monarch migration is the Sierra Madre Oriental mountain chain, 2) the canyons and canyon walls, and 3) the Gulf of Mexico also influence Monarch Migration."

Who Saw the Most Monarchs This Week? Migration-rate Math
Follow the link below to a few of this week's observations:

How to Report Your ObservationsReport Your Sightings
Put your monarch news on the map! Please send reports of monarchs flying, feeding, and resting. When you report your observations, include wind speed and direction. For instructions see:

The Next Monarch Migration Update Will Be Posted on November 4, 2005.


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