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After huge losses last year, Monarch butterflies come back strong

Sunday, February 23, 2003

By Lisa J. Adams, The Associated Press

MEXICO CITY -- Scientists are marveling at the impressive comeback of Monarch butterflies, which once again are carpeting the fir trees of central Mexico in a sea of orange and black wings -- despite a deadly freeze last year that killed hundreds of millions.

Hard rains and biting cold in the central states of Michoacan and Mexico in January 2002 killed 75 percent to 80 percent of the Monarch butterflies that make a 2,000-mile journey from the eastern United States and Canada.

The unprecedented numbers of deaths -- some estimated as many as 500 million butterflies perished -- followed by drought conditions last summer and decreased levels of butterfly sightings in the United States, prompted concern that fewer numbers of the insects would arrive south of the border this year.

But the butterflies came -- en masse. Scientists estimate anywhere from 200 million to more than 500 million monarchs are now hanging in enormous clusters in a 20-acre area of forest.

"That's at least twice what we expected," said Chip Taylor, an entomologist at the University of Kansas and director of Monarch Watch, a network of Monarch butterfly researchers based in Lawrence, Kan.

"It's a little bit of a mystery. ... There's obviously something we really have to learn about where these butterflies come from and how successful they are. ... But it's quite clear that they have recovered." The annual migration of the butterflies -- they come to Mexico in late October and depart in late March -- is an aesthetic and scientific wonder that has captivated the imagination of scientists, nature lovers and tourists.

Scientists still don't fully understand what guides generations of butterflies to the same place each year. Each migrating group is at least three to five generations removed from the previous arrivals.

The key to the butterflies' comeback this year was the size of the colonies that arrived in Mexico before the killer rains of January 2002, said Lincoln Brower, a professor emeritus of zoology at the University of Florida who has been studying Monarchs for 47 years.

Brower calculates that as many as 650 million butterflies migrated to Mexico during the last migratory season and that as many as 500 million of them died. As many as 150 million survived, moved on and successfully reproduced in Texas, Florida and other parts of the U.S. Gulf coast in the spring, he said.

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