Monarchs fly north toward uncertain future

U. KANSAS (US)—Low temperatures, storms, and habitat destruction made it a tough winter in Mexico for monarch butterflies, but the news is not all doom and gloom.

“I spend a lot of time fretting over the status of the monarch population and I’m always searching for factors or data that will help me understand the past as a way of predicting the future trends in monarch numbers,” says Chip Taylor, director of Monarch Watch at the University of Kansas.

As the butterflies migrate through Texas and continue northward across the Great Plains this spring, Taylor has poured over data from a network of monarch observers, hoping to gauge the well-being of the butterflies. But he says it is difficult to pin down their numbers with precision.

“This returning population has been most unique,” Taylor says. “The data clearly shows that monarchs were limited to Texas this spring more than in any of the previous 10 years.

“What does this mean? Was the dispersal of monarchs limited this spring because of the lower than average temperatures or because the population is low or some combination of both? The answer is probably the latter—a combination of low numbers of returning monarchs and lower temperatures.”

More positively, Taylor says, “the conditions for growth in the monarch population in Texas have been exceptionally favorable the last two months.

“The temperatures have been moderate and due to adequate soil moisture, the milkweeds and nectar sources have been abundant. In addition, the fire ants have been scarce having not recovered from the prolonged drought of last year. So, small population or not, the monarchs should be off to a good start.”

The first generation monarchs that come north from Texas in the next six weeks, along with weather conditions in the northern breeding range during the summer, will determine the overall health of the butterfly population, Taylor says.

Gardeners can help the butterflies by planting milkweed and other monarch-friendly plants.

“We need the public to pitch in to save the monarch migration,” says Taylor. “Without an effort to protect monarch habitats and restore milkweeds, this incredible migration will slowly fade away.”

Taylor encourages gardeners, homeowners, schools, governments, and businesses to plant monarch “way stations” consisting of milkweeds and other butterfly plants, in hopes that the dedicated habitats will sustain a threatened population during its migration.

“The size of the overwintering population last year was 1.92 hectares and, with a modest increase this summer, the population might get back to this number,” Taylor says.

“If the conditions for the rest of the summer are highly favorable, a winter population of 4 hectares is possible—but that doesn’t seem likely at this point.

“In any case, the winter population of 2010 is certain to be below the long-term average of 7.44 hectares.”

More University of Kansas news: www.news.ku.edu/

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