Monarch butterflies listed as “endangered”

The International Union for Conservation of Nature (IUCN) listed the butterflies on its “red list” of threatened species. The group estimates the population of the butterflies has dwindled by more than 20 percent over the last 10 years. Nick Haddad, a conservation biologist at Michigan State University, and Stuart Pimm, an ecologist at Duke University, were not involved in the listing but said they also are concerned about the species’ rate of decline.

What about other species? The IUCN also announced that estimates of the tiger population are up about 40% more from their 2015 estimates. The numbers reflect better methods for counting the felines, as well as a potential increase in the official count. Nonetheless, tigers remain designated as “endangered.”

Dig deeper: From the WORLD archives, read John Dawson’s article about how butterflies are more efficiently designed than scientists realize.