Millions of Monarch Butterflies and the Quest to Count Them

Abstract

Monarchs are capable of amazing feats! They transition from caterpillars to beautiful butterflies. During migration, they fly for thousands of miles—from the northern part of the United States and southern Canada to Mexico. But monarch butterflies are in trouble. In the past 25 years, citizens and scientists have reported fewer and fewer of them. There were less than half as many monarchs in 2020 as in 2019. Parks across the United States, like Rocky Mountain and Indiana Dunes National Parks, host the monarchs along their migration paths. The park rangers are helping scientists track monarchs through “capture, tag, and release.” With this method, anyone who sees a tagged butterfly can report when and where they saw it. By tracking monarchs along their migration paths, we expect to learn where they run into problems. Scientists are also using new technology to count monarchs in their winter habitats.