Monarch Butterfly Migration Update: March 14, 2001
Today's Report Includes:
Have the First Migrants Reached Texas?
The first inland sighting in Texas, over 130 miles west of the Gulf Coast, occurred on March 3rd:
The Aschens, who have been carefully monitoring monarchs on the Gulf Coast all winter, noticed directional flight by a monarch they saw last Friday:
If you live in Texas or the other Gulf States, please keep your eyes on the skies--and be ready to report monarchs!
Also watch for signs of the first monarch eggs and larvae.
Milkweed Emerging on the Migration Trail
This map shows where observers have reported milkweed emerging so far this spring:
We hope you will help us monitor the spring emergence of the monarch's food plant across North America.
Field Notes from the Mexican Monarch Sanctuaries
by Dr. Bill Calvert
March 12, 2001
The snow is gone from nearly everywhere but the highest elevations. Since it never became very cold following the storm, most of the butterflies were spared. (It's during the cold, clear nights after a storm that wet butterflies are particularly susceptible to freezing.)
If the clear weather persists tomorrow when we visit Rosario we can expect a butterfly blizzard. Warm, clear weather stirs butterflies up to a frenzy. There is much movement of the colonies downslope. Many millions fly through the woodlands each day to take water and nectar, and perhaps to exercise their wing muscles in preparation for their return migration to the north.
Millions of Monarchs Eaten Each Year by Predators
Before the monarchs arrived here in November, there was not a single butterfly wing on the ground. At the end of the season in March, the forest floor is peppered with dead butterflies. In a typical year, we estimate upwards of 12-15% of the entire over-wintering population dies due to predatory activities. Millions of monarchs clustered together are a rich source of food--and easy prey. But only for those predators who can successfully eat monarchs.
There are 3 main monarch predators in the sanctuary, one mouse species and two bird species. Close inspection of a dead butterfly gives a clue as to its predator:
Increased Mating Signals End of Wintering Season
Because their lives will soon end, the monarchs must now prepare to
pass their genes to the next generation. Mating increases as the over-wintering season draws to a close. In late February, for example, one might see 5 or more mating attempts in a 10 X 10 foot area. Of these, only about 1 in 10 pairs actually join to mate. Most pairs (90%) break apart just as they strike the ground.
By mid-March, mating attempts and successes have increased dramatically. Where 1-5 mating pairs could be seen at one time in the trails below the colonies, we'll now see three times as many mating pairs leading up to the monarchs' departure.
Mating proceeds like this: A male patrolling the canopy grasps the wings of a female, using the claws on his feet as he encounters her. The pair parachutes down to the ground. If he manages to attach to her (about 10% of the time), she folds her wings and he then flies off with her, if he can, to a safe perch where mating is completed.
Next week will be my last week here for the season, so I'll phone in one more report.
Recommended Web Site:
Monarch Butterfly Nuptial Flight Research
An interdisciplinary team at Cal Poly is studying the nuptial flight of monarchs. Be sure to visit this site which includes movie clips of the monarch's nuptial flight!
Bienvenidos al tiangis en Angangueo!
"Welcome to the Market in Angangueo! It's 9:01 a.m. Monday morning, and along every winding street, at every town corner and in all the store windows you find customers and merchants from near and far. They have all set aside the entire day to exchange goods for pesos. Many of the delights found at the tiangis (a large community market, usually held weekly on a designated day of the week) can be seen as we wander through the streets and among the vendors of Angangueo.
"At the end of the day, join the parade as hundreds of campesinos return to their homes in the surrounding mountains, traveling by foot and donkey, laden with the day's treasures. Leading the pack are the young and energetic, typically boys running up the steep hillside with their donkeys, followed by girls walking and talking with their friends. Then come the men, usually carrying a heavy load. Much later come the mothers with small children. And, at the end of the trail, come the elderly who are tired but happy to continue the weekly tradition of a trip to town."
Link to Collection of Bilingual Vignettes
Life in the Sanctuary Region
You'll find a total of 12 bilingual vignettes, including the following which have not been highlighted this spring:
How to Respond to Today's Challenge Question:
1. Address an e-mail message to: email@example.com