There are fewer butterflies in Texas skies

It's butterfly migration season, and while many still flutter through Central Texas, some populations have been dwindling over the past two decades, in line with nationwide trends.

Why it matters: Butterflies are important pollinators, and their populations are barometers of a healthy ecosystem.

• A combination of climate change, pesticide use, habitat loss — land is converted for agriculture or development — could be responsible for their declining populations, the New York Times reports.

State of play: The study by researchers from Michigan State University found that 106 of the 147 butterfly species found in the Austin area are decreasing nationally, but it's unclear how their numbers have shifted locally.

• 24 species are increasing in population, and 17 have seen little change.

The big picture: Researchers analyzed 12.6 million individual butterflies across 35 monitoring programs from 2000 to 2020.

• They found that the U.S. has lost 22% of its butterflies in the last 20 years.
• "The loss that we're seeing over such a short time is really alarming," Elise Zipkin, a quantitative ecologist and one of the study's authors, told the New York Times.

Case in point: Several butterfly species found in Austin are declining nationwide — Celia's Roadside-Skipper is down 68%, the Red Admiral has dropped 44% and Spicebush Swallowtail has decreased 15%.

Zoom in: In Leander, city officials are working to help monarch butterflies by joining the Mayors' Monarch Pledge — an effort by the National Wildlife Federation.

• The city placed signs along a 6-mile stretch of Ronald Reagan Boulevard to let residents know that Leander is delaying mowing the area until June for milkweed growth (the only plant the butterflies will lay eggs on).

✔️ Pro tip: If you are planting a butterfly garden, include pesticide-free nectar and host plants, Mills says.

• The Xerces Society for Invertebrate Conservation has resources to help decide which plants to plant.