Wednesday, September 27, 2017

Painted Ladies

I was having one of those driveway moments. A news story on NPR had caught my attention as I pulled into the Cable Community Farm, so I cut the engine and stared into space while listening to its conclusion. First my eyes were drawn to yellows and purples of the brightly blooming pollinator garden near the farmhouse. Then the movement really caught my eye.



A big bush of purple aster flowers was absolutely fluttering with activity. There was no quiet place to rest my gaze. Bees buzzed along of course, but the butterflies really stole the show.

Forgetting the news story, I hopped out of the car, grabbed my camera, and went to investigate. My first hope was that this was a cloud of Monarchs, since their plight has earned my sympathy and I’m cheering for them as underdogs. But although they shared the same orange and dark base colors as Monarchs, the pattern on these butterflies was distinct. Black-and-white upper corners highlighted orange wings with dark brown spots. These dozen or more afternoon visitors were Painted Ladies.



While Monarchs are lauded for their incredible migrations, they aren’t the only migratory butterflies; they are just the one with the most dependable schedule. Painted Ladies are incredible migrators, too, and travel from the southern U.S. and Mexico up to the northern U.S. and Canada. Some years we barely notice them, and some years they are wildly abundant.

Also called the Cosmopolitan, they are found on every continent except Australia and Antarctica. Painted Ladies are the most widely distributed butterfly in the world. They migrate by the millions from North Africa, the Middle East, and Central Asia up to mainland Europe, and bestow upon Britain and Ireland the same spectacle we’re witnessing now.

While the butterflies interrupted my NPR driveway moment, they’ve become news on their own. Newspapers in Colorado and Quebec have reported on giant flocks of migrating Painted Ladies in the past few weeks, and the Vermont Center for Ecostudies sent out an e-newsletter encouraging people to report sightings on e-butterfly.org, a sister site to the more familiar eBird.org site developed by the Cornell Lab of Ornithology.

Why is there such an influx of these beauties this year and this week?

First, there was a particularly large and early flight north last April and May. According to Iowa State University researchers on their Painted Lady Research Site, a strong El Niño event in the Pacific Ocean dumped rain on southern California last winter. The desert bloomed. Painted Lady caterpillars aren’t picky eaters, and so found plenty of host plants, and then proceeded to munch them down. When those caterpillars became adults, they needed to move on in order to find a new food source. Scientists have long noticed a connection between Painted Lady abundance and El Niño years.

Our mild spring weather then allowed for an early northward migration of a now-abundant flock. The pioneers headed across the U.S. and far north into Canada. Painted Ladies were spotted in Iowa as early as March 10, which is two months earlier than normal. With such an early arrival, the butterflies were able to have two generations instead of just one. Together, these factors resulted in a population boom.

Normally that abundance of butterflies wouldn’t be visible to us, because they typically migrate at an elevation several thousand feet in the air in order to take advantage of favorable wind currents. Using the wind, they can travel up to 100 miles a day, and reach speeds of nearly 30 miles per hour. Recently, a strong southern weather flow has brought the migrators down. It’s not efficient for a tiny butterfly to try and fly against the wind, so they are taking a break and refueling. That’s why we’ve seen such amazing numbers nectaring on flowers (and getting hit on the road) recently.

As soon as the winds change, though, the little beauties will take off. Wisconsin is too cold for either the chrysalis or adult to overwinter, so they must take refuge to the south and recolonize our gardens each summer.



Speaking of gardens, as I observed the swarms of butterflies, bees, wasps, flies, and other insects that crowded each goldenrod frond, sunflower face, and aster fringe, it was abundantly clear that what we plant matters to wildlife. This pollinator garden at the Cable Community Farm was thoughtfully laid out by Sarah Boles of Northern Native Plantscapes. She made sure to include flowers that would bloom early, late, and throughout the summer in order to provide a continuous source of nectar and other resources.

So the beautiful abundance that we’re witnessing this fall is due to many factors, not the least of which is the fact that at some caring humans make it a point to provide habitat for a species other than our own.

Now that’s what I call a driveway moment.



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3 comments:

  1. I love this. Thanks so much for the thorough explanation of their huge numbers this year! I've been noticing it myself and hearing about it from many others. We've been tagging monarchs in the prairies near Madison, and the Painted Ladies have been quite a site. I'd be interested in hearing about the sources you tapped (on weather patterns, El Niño, etc) to put this "big picture" explanation together.

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  2. Hi Northwoods Space Girl! How cool that you'd been tagging butterflies. I'm happy to share my sources. The only reason I don't put more of them into the article is that they can interrupt the narrative sometimes. I got my first inspiration from the Vermont Center for Ecostudies: http://uwm.edu/field-station/painted-lady/. Iowa State University has a cool project, with some of the more detailed details: http://vanessa.ent.iastate.edu/. A global perspective here: https://butterfly-conservation.org/679-849/painted-lady.html. I also just Googled Painted Lady Butterflies in the news, and found reports from Colorado, the Dakota, and even the BBC of an abundance of butterflies.

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    1. Oh, Hi Maggie! I didn't realize that was you!

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