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Majestic Monarchs on the moveScientists keep careful watch on butterfly numbers
By Marsha Walton (CNN Sci-Tech)
(CNN) -- Can North America's majestic monarch butterflies bounce back? These orange-black-and-white insects, known to gardeners, farmers, and generations of school kids, died by the millions after a freak storm in January. Cold, wet weather in a usually dry time of year killed them at their winter retreat in Mexico. Scientists will monitor their numbers this winter in Mexico, and their return, via Texas, to the Eastern United States this spring. "The monarchs can stand being wet if they're not cold, and they can stand being cold if they're not wet," said Karen Oberhauser, professor of ecology at the University of Minnesota. "But the combination of freezing temperatures and wet butterflies is what caused the high levels of mortality. "In some of the colonies, 70 to 80 percent of the butterflies were killed; there were literally tens of millions of monarchs covering the ground," she said. On the moveMillions of monarchs are on the move from the U.S. and Canada to central Mexico for the winter. Some may have to wait it out if any of the harsh winds and rain from Hurricane Lili interfere with their flight path through Texas. The butterflies will arrive by early November, and stay in the high-altitude oyamel fir forests until March. Monarch numbers tracked in the United States were a third lower than average following January's killer storm, but the butterflies have recovered in the past from other kill-offs, Oberhauser says.. Long term, human factors may play a bigger part in monarch survival. Oberhauser says the butterflies spend the winter at about 10,000 feet (3,048 meters) in central Mexico. But logging and other changes in the ecosystem can disrupt their winter routine. When the forest is dense, it acts as a buffer, keeping temperatures warmer for the insects. Without that protection, they are more vulnerable to cold and wet conditions. "What we don't know is if they would go somewhere else if these sites were degraded to the point where they weren't acceptable," said Oberhauser, who has studied the butterflies since 1984. She works with scientists and nature groups in Mexico to keep the monarch habitat safe without threatening the livelihood of resident farmers. Program teaches importance
The Monarch Butterfly Sanctuary Foundation, established in 1997, supports small-scale economic development in Mexico and the efforts of Mexican students and professors to learn more about the needs and habits of the monarch. Some members are working on reforestation projects. One effort helps residents plant trees lower down on the mountain range, so farmers and loggers will be able to use the trees for building or fuel without disturbing the fir trees on which the butterflies depend. These plantations are expected to become a source of income for the residents. Oberhauser gets data throughout the summer about monarch eggs and larvae from an army of "citizen scientists" who are part of the Monarch Larva Monitoring Project. "The public is involved in real research. We have funding from the National Science Foundation, and we've set up a network of people, using a consistent method to count. They go out into a patch of milkweed, in a garden or park or roadside, so we can see how populations fluctuate, and make comparisons between years," said Oberhauser. Complex life cycleA single butterfly can lay up to 1,000 eggs, with an average of 700. About 10 percent survive after being laid on some variety of the milkweed plant.
It actually takes two generations of monarchs to complete the roundtrip from the Eastern U.S. to Mexico and back. One generation lives for eight or nine months, flying to Mexico and making it as far as the Southern United States on the return trip. There, they reproduce, and the offspring make the rest of the journey north. That second generation begins reproducing just three or four days after they emerge as adults, and die within a month. A third and fourth generation will make the next trip south to Mexico. One monarch participant, speech therapist Sue Clark, says she's been fascinated by monarchs for 30 years. A nature center volunteer, she shares the intriguing, four-week experience of monarch's progress from caterpillar to butterfly with youngsters in the Head Start program. The 3-, 4- and 5-year olds are responsible for feeding the milkweed plant to the caterpillars and keeping their cages clean. "Children with hands-on experience learn to respect the environment," Clark said. She says watching the transformation -- marking the days off on a calendar, gently handling the butterfly after it has emerged -- gives kids an opportunity to increase their language skills and gets them interested in scientific exploration. "It just fascinates them, they wonder what happened and they look for it to happen again," she said. Fears for the futureAfter chronicling the monarchs in Marquette, Michigan, for four years, she worries about the future of their habitat, not just in Mexico but in the U.S. "They are amazing. This migration is amazing," said Clark. "The whole system has to stay intact, not just the fir trees in Mexico, to preserve these treasures." Oberhauser agrees that the species is worth protecting. "If monarchs went extinct tomorrow it would not cause huge changes in the ecosystem," she said. "But they're an incredibly beautiful and interesting species. It's fair to liken them to a beautiful work of art or something else that is part of our world, and something that people are interested in, that makes connections between human life and nature."
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