“It’s just a catastrophic decline,” said Stuart Pimm, an ecologist at Duke University who was not involved in the new listing. “This is one of the most recognizable butterflies in the world.” The International Union for Conservation of Nature has added the migratory monarch butterfly for the first time to its “red list” of threatened species and labeled it “endangered” – two steps away from extinction. The team estimates that the monarch butterfly population in North America has declined between 22% and 72% within 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 quickly this butterfly could become even more endangered.” Haddad, who was not directly involved in the listing, estimates that the monarch butterfly population he studies in the eastern United States has declined between 85 percent and 95 percent since the 1990s. In North America, millions of monarch butterflies undertake the greatest migration of any insect species known to science. After overwintering in the mountains of central Mexico, the butterflies migrate north, reproducing many generations along the way for thousands of miles. Offspring arriving in southern Canada begin the journey back to Mexico in late summer. “It’s a real sight and it’s so awe-inspiring,” said Anna Walker, a conservation biologist with the New Mexico BioPark Society, who was involved in determining the new listing. A smaller group spends the winters in coastal California and then disperses in the spring and summer to several states west of the Rocky Mountains. This population has seen an even steeper decline than eastern monarchs, although there was a slight recovery last winter. Emma Pelton of the non-profit Xerces Society, which monitors 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,” he said, including planting milkweed, a plant the caterpillars depend on. Non-migratory monarch butterflies in Central and South America were not listed as threatened. The United States has not listed monarch butterflies under the Endangered Species Act, but several environmental groups believe they should be listed. The international association also announced new estimates of the global tiger population, which are 40% higher than the most recent estimates from 2015. The new numbers, between 3,726 and 5,578 wild tigers worldwide, reflect better methods for counting tigers and possibly an increase in their overall numbers, said Dale Miquelle, tiger program coordinator for the nonprofit Wildlife Conservation Society. In the past decade, tiger populations have increased in Nepal, northern China and perhaps India, while tigers have disappeared entirely from Cambodia, Laos and Vietnam, Miquelle said. They remain classified as endangered.
Follow Christina Larson on Twitter: @larsonchristina
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