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 research was funded by the U.S. Fish and Wildlife Service, which is debating whether to grant endangered species status to the insect.
Monarchs depend on milkweed plants to lay their eggs and on milkweed flowers for food. But agricultural pesticides, development, and climate change have severely reduced milkweed populations.
The destruction of winter roosting forests in California and Mexico have also hurt monarchs, whose “western population has fallen to about 300,000 from 10 million less than four decades ago,” says Reuters. “The migratory monarchs of the western United States have a 63 percent chance of extinction in 20 years and an 84 percent chance in 50 years if current trends continue, according to the study.”