The monarch butterfly's annual migratory journey from Mexico to the U.S. and then Canada is a breeze compared to the federal government's lengthy process to protect the dwindling species. Why it matters: The monarch — whose population has declined more than 80% since the 1990s — has waited more than 10 years for protection under the Endangered Species Act.

The Trump administration is reopening public comment on a proposed rule that would list the monarch butterfly as threatened under the Endangered Species Act.

The number of monarch butterflies overwintering this year in Mexico has nearly doubled, according to the annual census data from the World Wildlife Fund.