At Migration Peak, Monarchs Few In Number

Monarch butterfly numbers are at an historic low.

An opportunity earlier this week to spend a morning at prairie sites on the Lac qui Parle refuge made it clear to me. I saw only two monarch butterflies the entire morning, when this is the time of year that they should be as numerous as the prairie flowers blooming amidst the grasses.

“It’s just unbelievable, the lack of them,’’ said Dick Clayton, naturalist at Sibley State Park. He’s counted about a dozen monarchs so far in what should be the peak of the migration.

What’s happening?

Two years of bad weather coupled with the continued loss of the milkweed plants are the factors being cited.

Last summer’s drought took a toll on the monarchs. Journey North, an organization that monitors monarch butterflies in North America, reported that only 60 million monarchs over-wintered on their forested wintering grounds in Mexico, compared to the normal 350 million. That’s an 80 percent decline.

More trouble followed this year. The drought persisted in Texas and southern states, reducing the number of larvae able to develop and migrate. Monarchs leap frog their way north, with each successive generation advancing the wave. Those taking wing in Texas suffered again as they moved north. A cold spring and slow warm up meant plant development was weeks behind schedule.

Most believe it will take years for monarch numbers to recover, if they can. Monarchs lay their eggs on milkweed plant. Milkweed is declining throughout North America’s agricultural regions due to row crop cultivation.

And, it isn’t just the weather or human activity that can make life tough for monarchs. I watched as a wren swooped and made its breakfast of one of the two monarchs I had spotted on the Lac qui Parle prairie.