JACKSON, Wyo. — Wyoming’s visiting monarch butterflies will soon take flight toward warmer climates as summer begins to wind down.
Typically, by mid-August, monarch butterflies stopping over in Wyoming from Canada will continue on to overwintering sites in the mountains of central Mexico and coastal California, according to the U.S. Fish and Wildlife Service (FWS).
“Using environmental cues, the monarchs know when it is time to travel south for the winter,” the FWS wrote on its website. “Monarchs use a combination of air currents and thermals to travel long distances. Some fly as far as 3,000 miles to reach their winter home.”
The FWS wrote that researchers are still investigating the directional aids that monarchs use to find their overwintering location, including the magnetic pull of the earth and the position of the sun.
While little is known about the monarch’s stopover in Wyoming, the University of Wyoming’s Biodiversity Institute started a citizen scientist campaign in 2015 to help track monarch butterflies as they fly through the state over the summer and fall.
“Wyoming is not really on the main migration pathway of monarchs, but we still have over 100 observations of monarchs in different life stages that have been uploaded to the project,” Biodiversity Institute Project Coordinator Mason Lee previously told Buckrail.
The monarch is the only butterfly known to make a two-way migration, similar to birds, according to the FWS. Unlike other butterflies that can overwinter as larvae, pupae or even as adults in some species, monarchs cannot survive the cold winters of northern climates.
Monarchs roost in eucalyptus, Monterey pines and Monterey cypresses in California, and in the oyamel fir forests in Mexico. Tens of thousands of monarchs can cluster on a single tree to stay warm. Although monarchs alone weigh less than a gram, tens of thousands of them can sometimes cause branches to break.
This past spring, the FWS held a public comment period to help determine if the monarch butterfly should be listed as a threatened species under the Endangered Species Act (ESA). A final decision on this proposal not yet been made.
According to the FWS, monarch numbers in North America have declined over the past two decades, which has caused the agency to go “all in” on monarch conservation. Some of the butterfly’s threats include the conversion of grasslands to agriculture, urban development, widespread use of herbicides, drought, continued exposure to insecticides and effects of climate change.
