Migration habitat loss may not be causing monarch butterfly decline, new study suggests

By Michel Marizco
Published: Thursday, April 4, 2024 - 2:03pm

Western Monarch Butterfly
Lisa Hupp/USFWS Midwest Region
Western monarch butterflies.

Scientists have studied declines in the monarch butterfly population in the United States and Mexico for years. A new study suggests it’s even more of a mystery than researchers thought.

For decades, the monarch butterfly population has fluttered between healthy levels and the brink of extinction. The declines have been attributed to changes in the landscape vegetation they draw nectar from, like the milkweed that proliferates through Texas and Mexico. The study found that though the number of butterflies dropped, the milkweed landscape in those regions did not, ruling out a big change to their migration habitat.

Jay Diffendorfer is the research ecologist who led the study for the U.S. Geological Survey.

"They still have a decent number of threats. We still don’t know what climate change is going to do to them in the long run. And we hope they don’t hit such low numbers that they can’t bounce back," he said.

Researchers in Mexico hope to use the findings to expand conservation efforts in that country.

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