Craig Wilson, a senior research associate in the Center for Mathematics and Science Education and a long-time butterfly enthusiast, says reports by the World Wildlife Fund, private donors and Mexico's Michoacan state show that Monarch numbers will be down almost 30 percent in 2012 as they make their annual trek from their breeding grounds in Mexico and move across Texas.
The figures show an alarming decades-long decline in their numbers, Wilson says, adding that it is best "that we take the long view rather than yearly cycles.
"The latest information shows that Monarchs will be down from 25 to 30 percent this year, and that has been part of a disturbing trend the last few years," Wilson notes.
"Last year's severe drought and fires in the region no doubt played a part, resulting in less nectar for the Monarchs as they migrated south. But estimates show that each year, millions of acres of land are being lost that would support Monarchs, either by farmers converting dormant land for crop use – mainly to herbicide tolerant corn and soybeans – or the overuse of herbicides and mowing. Milkweed is the key plant because it's the only plant where the female will lay her eggs."
The loss of such lands is a critical factor in the Monarchs' survival, Wilson explains.
"Chip Taylor, who is the director of Monarch Watch at the University of Kansas, estimates that 100 million acres of land have already been lost that previously supported Monarchs," Wilson notes.
Most of the Monarch reserves are in the Mexican state of Michoacan. It's an area where Monarchs spend the winter and mate before heading north, Wilson points out.
In the spring, the butterflies leave Mexico and across Texas, and Wilson has noticed both eggs and young Monarch caterpillars feeding on milkweed in the Monarch Waystation, a butterfly garden outside his office. The adults will fly various routes through Texas, with the fourth generation eventually arriving in Canada.
This year, according to the Texas Monarch Watch, Monarchs covered about 7.14 acres of forest in their Mexican breeding grounds compared to 9.9 acres last year, and it shows a continued long-term downward trend in Monarch population since official surveys began in 1994.
Wilson says there has to be a national effort to save Monarchs or their declining numbers will reach the critical stage.
"We need a national priority of planting milkweed to assure there will be Monarchs in the future," he says. "If we could get several states to collaborate, we might be able to promote a program where the north-south interstates were planted with milkweed, such as Lady Bird Johnson's program to plant native seeds along Texas highways 35-40 years ago. This would provide a 'feeding' corridor right up to Canada for the Monarchs."Wilson says there are several websites to monitor Monarchs. They include http://www.texasento.net/dplex.htm, also http://www.learner.org/jnorth, and http://www.monarchwatch.org.
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Keith Randall | EurekAlert!
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