Monarch migration expected to be disappointing

09/01/2012 5:00 AM

03/15/2013 9:31 AM

Few things in nature are so small, yet so often bring such joy to Kansans, as monarch butterflies.

On the wide-open prairie, cowboys may halt their horses and watch the orange insects with tissue-thin wings push steadily southward.

In the highest buildings in downtown Wichita, workers may look up and smile as butterflies headed for mid-Mexico flutter by a window.

But this year’s monarch migration, one of Kansas’ most-enjoyed autumn rituals, is expected to be disappointing.

“People aren’t seeing what they should be seeing for migrations,” said Chip Taylor, director of Monarch Watch, a conservation group based in Lawrence. “It’s going to be much lower this year than last year, and that was a low year.”

Taylor, also a University of Kansas professor of biology, said this year’s drought has crippled monarch reproduction and survival.

Unlike last year, the drought stretches much farther to the north and east. That includes areas that are some of the country’s most productive regions for monarch production. The same region produces many of the migrating butterflies we enjoy seeing in Kansas.

And it’s not like the butterflies went into this summer with a strong population.

Declining habitat, populations

“The population is probably only 50 percent of the long-term average,” Taylor said. “There’s no question the monarch population is going down. It’s the same old story we hear over and over — loss of habitat.”

Taylor said research shows monarchs have lost around 160 million acres of habitat since the mid-1990s.

“They’re losing about 2.2 million acres of habitat a year just to development,” he said. “That’s about 6,000 acres per day.”

And much of what was once their most fertile breeding grounds are no longer accommodating to monarchs because of changes in agriculture.

“Research showed that agricultural provided some of our most productive monarch habitat. Fields of soybeans and corn were important sources of milkweeds for monarchs,” said Taylor, who said milkweeds are about the only plant on which monarchs will lay eggs.

“It was ideal habitat because we had maybe 20 to 30 nice milkweed plants per acre in all those fields,” Taylor said.

That changed, though, with the advent of special herbicide-resistant soybean and corn plants that allowed farmers to spray fields and kill all vegetation except the crops.

Taylor said loss of milkweed plants in such fields has cost monarch butterflies about 100 million acres of productive habitat since about 2000.

Also, more and more prairies and pastures are being plowed and planted to corn each year because of high demand for highly profitable ethanol.

Drought’s effects

Taylor said hopes were high when America’s monarchs started working northward from Mexico in February. Some early rains had good milkweed growth in Texas when the butterflies began arriving there in early March.

But then things began getting tough because of the widespread drought.

Though female monarchs may lay eggs in milkweeds along 1,000 or more miles of their migrational trails, they die pretty quickly. When all works well, those eggs hatch and eventually become adult monarchs that reproduce within a few weeks.

The drought has hammered all-important milkweeds.

“The monarchs we see now may be three or four generations removed from the ones we saw migrating northward this spring,” Taylor said. “We’ve had almost nothing for the last generation to lay their eggs on. About 50 percent of the counties in the whole country have been in some sort of serious drought.”

Missing, largely because of the heat and drought, are the lush wildflowers from which every generation of monarchs draws life-giving nectar.

Taylor rates the conditions around Lawrence, often some of the best monarch habitat in Kansas, as very poor.

“Most years when you drive across the Kansas countryside you see acres and acres of blooming sunflowers, but this year they’re few and far between,” Taylor said. “It’s that way with most plants, and even if they grow, most of them won’t bloom and have nectar.”

It’s largely been the same, or worse, in much of the eastern Dakotas, Minnesota, Wisconsin, Michigan and Iowa, states that produce many of the monarchs that normally migrate southwestward through Kansas.

In his office, Taylor often checks online to see reports of where sizable concentrations of monarchs are roosting as they gather to migrate in those states.

A check last week showed just three such roosts in that entire region. The same date in several past years showed 30 or more such roosts.

And life won’t get any easier for the fewer monarchs that head this way because of the lack of wildflowers in Kansas.

Taylor said the butterflies may adapt their migrational routes to get the best they can from the state.

Many monarchs may stick more to migrating along stream and river valleys, where it’s generally cooler and wetter and wildflowers have their best chances to bloom.

“Moving across open country may be too difficult for them this year,” he said. “They’re pretty good at finding nectar when things are bad.”

Also, some recent rains may help some plants to flower and provide nectar.

Still, he thinks many butterflies may be short on the body fat needed to make the trip to the high mountains of Mexico, where they gather up to 25 million per acre during good years.

The stress from the trip could also make it hard for many to survive the Mexican winter.

Taylor said a severe winter storm can kill 70 percent of the monarchs in Mexico.

Hopefully winter and spring moisture across the country will have healthy crops of milkweed and other plants in great supply as the 2013 crop of monarchs head northward.

If there is a silver lining, it is that maybe the low numbers of monarchs will bring awareness to what’s happening to them, possibly America’s most recognizable insect.

Hopefully that will also draw attention to what’s happening to other important insects, too.

“When we lose monarch habitat, we’re losing the habitat of a lot of our pollinator species, and we’re losing them at alarming rates, too,” Taylor said, “They distribute pollen for about 70 percent of our vegetation out there, and that’s where we get our fruit, nuts, berries, seeds and leaves. You pull (pollinators) out of the system and the system collapses.

“It’s becoming a complicated world out there.”

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