Monarch Migration Update: February 25, 2005
Today's Report Includes:
- Monarchs in the News: Population Lowest in a Decade
- International Team of Scientists Responds
- Monarch Population Dynamics: Let Me Count the Ways
- Field Notes from Mexico from Dr. Bill Calvert
- Where Find Water in the Dry Season? Discussion of CQ #3
- Backyard Observation Reveals a Clue
- Dr. Brower: The Cloud, Mountain, Fog, Forest Connection
- Habitat Conservation and Water: What Scientists Didn't Know
- Life in the Sanctuary Area: Water Resources for Families
- Food, Water, Shelter, and Space: Shelter from What?
- Even Dewdrops Can be Dangerous: Challenge Question #4
Monarchs in the News: Population Lowest in a Decade
Every winter the Mexican government measures the size of the known butterfly colonies. Like a snapshot in time, these annual winter measurements give scientists a chance to estimate the size of the entire over-wintering population. Last summer and fall, monarchs were so scarce in the north that the results from Mexico last week were not a surprise: "Esta superficie es la más pequeña documentada durante la pasada década." (This coverage is the smallest documented during the past decade.)
| Monarch
Population Estimates in Mexico 1994/1995-2004/2005 |
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Report
from World Wildlife Fund-Mexico (Original, in Spanish) |
International Team of Scientists Responds
The long-awaited results were of great concern to scientists. They suspect the following may have led to this year's low population estimate:
- Winter storm mortality in Mexico was high last year (2003-2004).
- Cold and wet weather during the 2004 summer breeding season slowed population build-up.
- Habitat deterioration of the Mexican overwintering sites has made monarchs more vulnerable to storms.
- Herbicides are eliminating summer breeding habitat in the U.S. and Canada.
- Herbicides are also eliminating adult nectar resources in the U.S. and Canada.
If the phenomenal migration of the monarch butterfly is to survive, warned the scientists, their habitat must be protected in Mexico, the United States, and Canada.
Monarch Population Dynamics: Let Me Count the Ways
How many monarchs are there? What causes monarch numbers to change from year to year? Many complex factors interact that ultimately determine a population's size. To appreciate the scientists' challenge think the problem through for yourself!
Field Notes from Mexico from Dr. Bill Calvert
"From the butterfly point of view, it looks like this is a good winter," said Dr. Calvert by phone last week. "It's very, very wet this year, and they have had a mild winter. There's not much mortality. (There are not very many monarchs on the ground. Monarchs on the ground have either starved to death or have been eaten.) But then, it's still early in the season so we don't know what's going to happen."
Dr. Calvert has two weeks off before his next tour, so he's visiting his favorite sites in Mexico. We will hear from him again the week of March 7th when he's back in the butterfly region.
Where do Monarchs Find Water in the Dry Season?
Discussion of Challenge Question #3
Students in Texas, New Hampshire, California, and Rhode Island named 13 possible sources of water! Before reading their ideas, consider this backyard observation:
| 1. Carefully describe what you see in the picture below. | 2. Then read Dr. Calvert's observations in Mexico. | 3. ...and see how students answered Challenge Question #3 |
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Dr. Brower: The Cloud, Mountain, Fog, Forest Connection
When Isabella said monarchs might get water "from little drizzles," she was right! Read or listen to Dr. Brower’s description of "fog drip." This source of water adds moisture to the colony during the dry season. Draw a series of pictures and write your own captions to illustrate how "fog drip" works. Why does Dr. Brower say the trees are so important?
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Dr. Brower: The Cloud, Mountain, Fog, Forest Connection |  |
Habitat Conservation and Water: What Scientists Didn't Know
Back in 1986, when land was put aside for the monarchs, scientists did not realize how the colonies used the watersheds during the season. In 2000, new sanctuary boundaries were made to meet the monarch's habitat needs.
Life in the Sanctuary Area: Water Resources for Families
How does life change for people during the rainy and dry seasons? Maria Luisa and her family share their story. Local inhabitants, especially women, consider water scarcity their main environmental problem, says Monica Missrie formerly of World Wildlife Fund-Mexico. Water shortages during the dry months are becoming more and more critical, she says.
| Water Resources for Families |
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Recursos de Agua para las Familias de la Región del Santuario |
Food, Water, Shelter, and Space: Shelter from What?
This season, we're exploring the monarch overwintering habitat--food, water, shelter, and space. Next week we will focus on shelter. To get ready, consider this:
Even Dewdrops Can be Dangerous: Challenge Question #4
"From what do you suppose monarchs need shelter? List as many needs for shelter as you can. Also, explain why you think even dew drops can be dangerous for monarchs."
How to Respond to Today's Monarch Challenge Question
1. Address an e-mail message to: jn-challenge-monarch@learner.org
2. In the Subject Line of your message write: Challenge Question #4
3. In the body of your message, answer the question above.
The Next Monarch Migration Update Will Be Posted on March 4, 2005
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