Butterfly Migration Update: October 28, 2005
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!
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:
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.
Coming Down From the North
Monarchs continued to pour down from the north last week. Here are more
highlights, from south to north:
Gulf Coast: The Wave Arrives
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."
Gulf Coast: Which Direction?
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?"
observation raises many interesting questions!
- Had the
butterflies been caught in hurricane winds?
- Were they
struggling to return to land?
did these monarchs come from?
direction do monarchs go when they hit the Gulf Coast in Florida?
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
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."
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.)
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.
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."
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.
After reading today's update:
"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
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?"
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.
of Challenge Question #8: Geography and Migration
4 students of Heritage Elementary in Wake Forest, North Carolina,
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."
Saw the Most Monarchs This Week? Migration-rate Math
Follow the link below to a few of this week's observations:
to Report Your Observations
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:
Next Monarch Migration Update Will Be Posted on November 4, 2005.
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