SAN FRANCISCO — The number of western monarch butterflies wintering in California declined by 30% last year, likely due to the high humidity, researchers announced Tuesday.
Volunteers visiting sites in California and Arizona around Thanksgiving removed 230,000 butterflies from 330,000 butterflies by 2022, according to the Xerses Society, an environmental nonprofit focused on invertebrate conservation. It is said that more than one fish was caught.
Populations of the orange and black insects have rebounded to hundreds of thousands in recent years. In 2020, the number of butterflies plummeted to just 2,000., the lowest on record. But even though the butterflies have recovered, their numbers are still far below what they were in the 1980s, when monarchs numbered in the millions.
Scientists say butterfly populations are critically low in western states because housing construction and increased use of pesticides and herbicides are destroying milkweed habitat along migratory routes. Says.
Climate change is also one of the main factors in the monarch butterfly's extinction, preventing the butterflies from migrating 3,000 miles (4,828 km) each year to coincide with spring and wildflower blooms.
“Climate change is creating challenges for many wildlife species, and the monarch butterfly is no exception,” said Emma Pelton, monarch butterfly conservation biologist at the Xerces Society. “We know that the severe storms we saw in California last winter, atmospheric rivers flowing back to back, are on some level connected to climate change.”
Western monarch butterflies migrate south from the Pacific Northwest to California each winter, returning to the same places and even the same trees, where they huddle together and stay warm. They breed multiple generations along the route until they arrive in California, usually in early November. When warm weather arrives in March, it spreads east of California.
East of the Rocky Mountains, another population of monarch butterflies migrates from southern Canada and the northeastern United States into central Mexico. Scientists estimate that monarch butterfly populations in the eastern United States have declined by about 80% since the mid-1990s, but the decline in the western United States is even steeper.
Source: www.nbcnews.com
