Monarch Butterfly Migration Update: February 28,
2003
Field Notes from Mexico by Dr. Bill Calvert At El Rosario, the monarchs decided not to cooperate this year. They didn’t form their colony within the loop of cement stairs which were provided for them and for the visitors. Instead, the colony is north of the Llano de Conejo. This choice by the butterflies requires the butterfly enthusiasts to walk about a mile to see them. At Chincua, the butterflies chose the often-used location in the Arroyo Hondo. The Chincua colony has now moved down-slope maybe 100-200 meters from its January location. In contrast, the Rosario colony did not appear to have moved at all last week, and has moved only a little this week. The difference in movement between the two colonies may be due to the location of water. It is likely that through the dry part of the butterflies’ overwintering tenure, the colony will always move in the direction of water. Ironically, if the Rosario colony moves down the arroyo above which it’s now positioned, the butterflies will no longer be on ejido El Rosario’s land. Instead they’ll be on land owned by ejido La Salud. (Only edjio El Rosario now receives income from tourists.) Perhaps to avert this, the Rosario ejido is irrigating to provide water for the butterflies where they are presently located. The most noticeable butterfly behavior seen during the past week was the striking behavior called “cascading,” in which literally tens of thousands of butterflies suddenly push off their perches, en masse, and fall downwards. After a fall of 3-5 meters they begin to fly, all in the same direction. The phenomena is absolutely awesome. Sometimes one cascade will trigger another, resulting in a sequential cascading from numerous branches in the colony. The cause and purpose of this spectacular behavior remains a mystery.
Until next week, Unsolved Mysteries: Challenge Question #7 After years of observing cascading behavior, Dr. Calvert says the cause and purpose of the behavior remains a mystery. What experiment could you design to try to tease out the cause of cascading? Another question: Dr. Calvert says the presence of people might cause cascading. What do you think about this:
(To respond to this question, please follow the instructions below.) Domestic Needs for Wood Discussion of Challenge Question #5 Mrs. Swentzel's third grade class from Stanhope (Byram), NJ did a fantastic job discovering the many ways wood is used in the sanctuary area. "We brainstormed as a class and came up with the following list
before we saw the video: wood would be used to make chairs, tables, and
other furniture, tools, utensils, bowls, firewood for heating and cooking,
wood for making houses, canes, fencing, boxes, wagons, and carving. According to Ed Raskin of the Michoacan Reforestation Project, a typical family uses 2 burrow-loads of wood per week for firewood alone. One burrow carries a half a cubic meter of wood. This means that a typical family would use some 50 cubic meters of firewood per year. Multiplying this figure by the rural population in the region of 90,000, the equivalent of 40,000 mature oyamel fir trees is needed for firewood. Reserve-Area Families Receive
New Stoves "It’s not as warm, but it is nice when my husband is feeling lazy about collecting wood," laughed Señora de Jesus about her new government-issued gas stove. "We can cook immediately, we don’t have to wait for the fire." In Novermber, 2002, the governments of Michoacan and Mexico provided stoves to families who live in the immediate vicinity of the sanctuaries. While the stoves are efficient, the traditional wood stove is hard to give up. The kitchen stove is the only source of heat during the cold winter months at 10,000 feet altitude. Concerned about the truckloads of wood they see coming down the mountain and passing their store, the Romero family in downtown Angangueo is also trying to cut back on their use of firewood by cooking with gas. "It’s cold, but we’re willing to make the sacrifice," says Estela Romero.
Alternare Stoves Cut Wood Use by 50% No Indoor Heat Visiting American Family Found Angangueo COLD
"I quickly began to understand how important this microclimate was for the butteflies," said Dave. Why No Heat? Can You Spot the Cause? Challenge Question #8 In next week’s update, we'll discuss another significant cause of deforestation in the monarch region. Here's what it looks like:
(To respond to this question, please follow the instructions below.) Discussion of Challenge Question #6 Who Ate These Butterflies?
Mrs. Nunnally's second grade class at Peter Woodbury School in Bedford, NH, looked at the pictures of butterflies. “We think the predators were: First Milkweed Emerging on the Migration Trail! Exciting news was reported from Texas. The first milkweed of the season! “Here’s a photo of early Asclepias viridis sprout from yesterday (2/23/03),” says Harlen Aschen. “The sanctuaries are only about 650 miles SSW of here and, with good southerly March winds, they could make it in less than a week. We will get serious about watching for very faded monarchs on a dedicated northbound course starting next weekend (3/1/03) but don't expect much for another week after that-- maybe the fifteenth of March.” Before the Migration Begins...
How to Respond to Today's Challenge Questions:
1. Address an e-mail message to: jn-challenge-monarch@learner.org
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