It has been a hard winter for Monarch butterflies, according to Chip Taylor, director of Monarch Watch at the University of Kansas. Taylor said that low temperatures, storms and habitat destruction have all threatened the butterflies' overwintering population in Mexico.
"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," Taylor said.
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 said it is difficult to pin down their numbers with precision.
"This returning population has been most unique," Taylor said. "The data clearly shows that monarchs were limited to Texas this spring more than in any of the previous ten 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."
Nonetheless, Taylor said that data on the butterflies "is not all doom and gloom."
"The conditions for growth in the monarch population in Texas have been exceptionally favorable the last two months," Taylor said. "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 Monarch Watch director said that the health of butterfly population would be determined by the number of first-generation monarchs that come north out of Texas over the next six weeks and weather conditions throughout the northern breeding range over the remainder of the summer. Depending on these factors, the number of monarchs could stay steady, decline or increase compared to last year.
But gardeners can help the butterflies by planting milkweed and other monarch-friendly plants, Taylor said.
"We need the public to pitch in to save the monarch migration," said 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 said. "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."
Explore further: Warning coloration paved the way for louder, more complex calls in certain species of poisonous frogs