For the second year in a row, the number of monarch butteflies spending the winter in Mexican forests has declined, said Alejandro Del Mazo, Mexico's commissioner for protected areas.
Monarch butterflies west of the Rocky Mountains are facing extinction, as the number wintering in California has plummeted by more than 90 percent since 1980, says a study published by the journal Biological Conservation. The U.S. Fish and Wildlife Service is debating whether to grant endangered species status to the insect.
Under terms of a settlement, the Interior Department will rule by June 30, 2019, whether the monarch butterfly, which has suffered a huge drop in population, deserves protection under the Endangered Species Act, said two environmental groups. The groups say without help, the well-known orange-and-black insect is at risk of extinction.
Two researchers at Cornell say the factors behind the decline in monarch butterfly populations are wider spread than the loss of milkweed, their summertime food source. They say the list includes sparse nectar sources in the fall, adverse weather and fragmentation of habitat.
The population of the Eastern monarch butterfly declined 84 percent in less than two decades, says a team of researchers.
The monarch butterfly population, "after years of being ravaged by severe weather and shrinking habitats," shows signs of recovery, reports the New York Times.
The main cause of declines in the monarch butterfly population is loss of habitat in breeding grounds in North America, particularly the U.S. Corn Belt, says research by the University of Guelph.