The migratory monarch butterfly endemic to North America has been categorized as an endangered species by the International Union for Conservation of Nature.

Why it matters: The monarch's native population has shrunk between 22% and 72% over the past decade. Its decline is largely due to climate change, deforestation and pesticide use, which kills the milkweed the monarchs feed on, the IUCN said Thursday after adding the butterfly to its "red list" of threatened species for the first time.

Catch up fast: The monarch is the only species of butterfly known to make a two-way migration every year.

• Eastern monarchs sometimes travel more than 3,000 miles, heading north to places in the U.S. and Canada for the summer and south to Mexico for the winter. Western monarch often fly shorter distances and overwinter in California.

By the numbers: The western monarch is at the greatest risk of extinction, the IUCN said, with its population declining from as many as 10 million in the 1980s to less than 2,000 last year.

• The eastern monarch's population shrunk by 84% from 1996 and 2021.
• While both groups of monarchs have seen slight resurgences over the last year, conservationists warn it may not be enough to save the embattled species.

What they're saying: “It is difficult to watch monarch butterflies and their extraordinary migration teeter on the edge of collapse, but there are signs of hope," said Anna Walker, a member of the IUCN SSC Butterfly and Moth Specialist Group.

• "From planting native milkweed and reducing pesticide use to supporting the protection of overwintering sites and contributing to community science, we all have a role to play in making sure this iconic insect makes a full recovery,” Walker added in a statement.

The big picture: The U.S. Fish and Wildlife Service in 2020 acknowledged that the monarch meets listing criteria under the Endangered Species Act, but declined to add it, stating at the time other species were in greater danger.