The monarch butterfly, chosen as Illinois’ State Insect in 1975, fluttered one step closer to extinction Thursday, as scientists put the iconic orange-and-black insect on the endangered list due to its rapidly declining numbers.
“It’s just a devastating decline,” said Stuart Pimm, an ecologist at Duke University who was not involved in the new list. “This is one of the most recognizable butterflies in the world.”
The International Union for Conservation of Nature first added the migratory monarch butterfly to its “red list” of endangered species and categorized it as “endangered” — two steps away from extinction.
The group estimates that the monarch butterfly population in North America has decreased by 22% to 72% in 10 years, depending on the method of measurement.
“What we’re concerned about is the rate of decline,” said Nick Haddad, a conservation biologist at Michigan State University. “It’s very easy to imagine how very quickly this butterfly could become even more endangered.”
Haddad, who was not directly involved in the list, estimates that the population of monarch butterflies he studies in the eastern United States has declined by 85% to 95% since the 1990s.
In North America, millions of monarch butterflies undertake the longest migration of any insect species known to science.
After wintering in the mountains of central Mexico, the butterflies migrate north, breeding for several generations for thousands of miles along the way. The offspring that reach southern Canada begin the journey back to Mexico at the end of the summer.
“It’s a true spectacle and so awe-inspiring,” said Anna Walker, a conservation biologist with the New Mexico BioPark Society, who was involved in determining the new list.
A smaller group winters on the California coast, then spreads over several states west of the Rocky Mountains in the spring and summer. This population has seen an even steeper decline than the eastern monarchs, although there was a small rebound last winter.
Emma Pelton of the nonprofit Xerces Society, which tracks western butterflies, said the butterflies are at risk from habitat loss and increased use of herbicides and pesticides for agriculture, as well as climate change.
“There are things people can do to help,” she said, including planting milkweed, a plant on which the caterpillars depend.
Non-migrating monarch butterflies in Central and South America were not listed as endangered.
The United States has not listed monarch butterflies under the Endangered Species Act, but several environmental groups believe it should be on the list.
The international union also released new estimates for the world’s tiger population, which are 40% higher than the most recent estimates from 2015.
The new numbers, of between 3,726 and 5,578 wild tigers worldwide, reflect better methods for counting tigers and possibly an increase in their total numbers, said Dale Miquelle, coordinator of the tiger program at the nonprofit Wildlife Conservation Society.
Over the past decade, tiger populations have increased in Nepal, northern China and perhaps India as well, while tigers have completely disappeared from Cambodia, Laos and Vietnam, Miquelle said. They remain designated as endangered.