Can Minnesota Monarchs survive Texas drought on Mexico migration?

4 monarchs.jpg

Photo credit: NATI HARNIK

This story caught my eye.

We’ve been reporting this summer and fall on the worst drought and wildfires in Texas history. It turns out millions of monarch butterflies make an annual pit stop in Texas to fatten up for the winter in Mexico. The Texas sized drought of 2011 may be a blow to many monarchs looking for critical fall food sources.

The story from the Washington Post.

“For the monarch butterflies, life is complicated enough even in a good year. Now, though, they’ve got to deal with Texas.

The monarchs in recent weeks have been beating their way south and west across eastern North America, riding winds a thousand feet above the ground, covering 25 miles or more every day. Now they’ve reached a vast area in Texas stricken by drought and charred by wildfires.

The butterflies are on their way to Mexico. They come from as far north as Winnipeg, Manitoba, and as far east as the islands of Maine. Many take a well-flapped route down the Eastern Seaboard before veering across the Gulf Coast. If they can make it through the gantlet of Texas, they will cross the Rio Grande and converge on a few acres of forest in mountains about 60 miles west of Mexico City. There, they spend the winter roosting, thick as quilts, on the branches of oyamel fir trees. In spring, they’ll head back north.

But it’s not clear how many will make it this year to their Mexican retreat, or what kind of condition they’ll be in when they get there.

They need water. They need flowers. They need nectar. The monarch butterfly is a hardy and vigorous insect, but whatever compels it to migrate south does not tolerate much flexibility in the itinerary. Going through Texas on the way to Mexico is what they’re hard-wired to do. And Texas is scorched.

“They’re going to be encountering a thousand miles of hell as they go through a nearly waterless, flowerless, nectarless landscape,” said Chip Taylor, an insect ecologist at the University of Kansas and the director of the nonprofit organization Monarch Watch.”

4 monarch.PNG

“Is this (monarch) heaven? No, it’s western Minnesota!”

More from the Kansas City Star. It turns out western Minnesota and the Dakotas are some of the few areas where monarchs are doing well these days.

“Pity the poor monarch.

The butterflies’ retreat from their summer range, stretching from New England to the Dakotas, is now heading into truly scorched earth.

Texas, especially, is crispy.

“The migration is just beginning to navigate a thousand miles of hell — a nearly flowerless/nectarless and waterless expanse,” wrote Chip Taylor, director of Monarch Watch, referring to the abnormally hot and dry stretch from central Kansas through northern Mexico.

The last of the big butterflies are passing through our area now. Wish them luck.

Just don’t expect to greet nearly as many next spring.

At one time we enjoyed a billion Eastern monarchs; Taylor thinks there may be a tenth of that today. Next summer? Who knows?

In a normal year, he said, “As they go south, they visit a lot of flowers, collecting nectar that are rich in sugar, and they convert those sugars to fat, which is stored in the abdomen. They’re heavier when they get to Mexico, which is interesting, since most migratory species lose weight on the trip. They spend most of the winter living off those fats.”

But first they have to funnel through Texas, where the vegetation, if it hasn’t dried up in the hottest summer on record, is likely burned up. About 21,000 fires — and some are still burning — have blackened more than 3.6 million acres. Too late for fall rains to help much there or in northern Mexico.

“Hey, more bad news,” Taylor interjected, with a pop-up on his computer screen, “it’s 101 degrees in Austin.”

So how many monarchs will make the fall trip safely but arrive too skinny to survive the winter or reproduce on the return trip north?

Since spring, Taylor, who is a professor of ecology and evolutionary biology at the University of Kansas, had predicted the numbers starting the march from the East Coast would be low. He was disappointed, however, by the counts from the Great Lakes Midwest (Ohio to Wisconsin). The only bright spots were the eastern Dakotas and western Minnesota, but still, populations overall are low.

Tagging in Texas will give Taylor a better sense of the survival rate over the last 500 miles. (The tags are a small circular sticker on the insect’s underside, which at first glace can look jarringly like a “Made in China” sticker.)

The grim backdrop to all of this is the elimination of nourishing milkweed across much of the farming region. This corresponds with the increased use of herbicide-tolerant corn and soybeans planted during the summer breeding times. Loss of habitat continues apace as well.

“All the scenarios I see going forward,” Taylor said, “it’s hard to see a positive one.”

PH

Comments are closed.