Monarch butterflies have begun their annual transcontinental journey north from their wintering grounds in Mexico, and butterfly enthusiasts in the southern United States are keeping their eyes peeled for the season's first flash of brilliant orange and black.

Already a few colorful visitors have been spotted in California, Florida and Texas, and spring's colorful onslaught is set to be a good one compared to last year's dismal monarch showing.

"The numbers coming back this year are definitely going to be better than the numbers coming back last year," said Chip Taylor, a professor and insect ecologist at the University of Kansas, and the director of Monarch Watch, a nonprofit outreach organization.

First generation flyers

Monarch butterflies spend the winter in the pine forests of Michoacán, in western central Mexico, festooning the trees by the millions and barely moving for months.

During the 2009 to 2010 season, the resting butterflies covered a mere 206,670 square feet (19,200 square meters) of forest — an area only about one-eighth larger than the average Walmart Supercenter store.

"That was an all-time low," Taylor told OurAmazingPlanet, "and then we had a whole series of winter storms that just knocked the daylights out of the population." It's difficult to pin down exact numbers, but Taylor estimates the monarch butterfly population was slashed in half.

Thanks to favorable breeding conditions in 2010, the population that returned to Mexico last fall was twice as large as the generation that left in the spring, setting the stage for a grand butterfly entrance this year.